Please help me diagnose my overheating issue

[Ryan S.]

Yesterday my car started to overheat on freeway. It turns out, fan was not coming on. I figured, my new otterstat failed. I still had another good otterstat so replaced it. But it still didn't work. I jumped otterstat wires and fans came on fine. One strange thing that I have noticed was that coolant didn't gush out when I replaced otterstat. Normally it would just pour out but hardly anything came out. I bled radiator and also noticed that not much of coolant came out. It took sometime for me to see some decent amount of coolant. I put almost 1 gal of coolant but level is somewhere in the middle. I have DMCNW coolant system bleed kit.


I am guessing that otterstats are fine but there is little or no coolant in pipe therefore otterstat is not activated??? I am not hearing any water pump noises but could it be water pump failure? When I opened coolant tank, I did see flow of coolants. Belts are all intact and working. I cannot find any leak anywhere:hmm: Next would be pressure test once the car cools down.

[DMCMW Dave]

Next would be pressure test once the car cools down.

There is undoubtedly still a lot of air in the system. Bleed the radiator (upper small hose on the right) and the engine (thermostat housing bleeder) again. If you have a pressure tester, that can help you bleed it - pressurize it to 5 psi or so and then open the bleeders until the air is out. Makes sure there is plenty of fluid in the header bottle when you start.

ALSO - with the engine cold, take the cap off the header bottle and start the engine. See if water is spraying into the bottle from the small bleeder hose that comes from the back of the engine. If not, it's a sure sign that the engine is full of air. If you do the bleeds and still don't see water coming from the bleeder, the tee at the back of the engine is probably blocked.

[Michael]

It's possible that you boiled your coolant out of the expansion tank and didn't see the steam. The question remains is what caused the car to overheat to begin with. Once the system is full and bled, your pressure test should show any leaks. After that there is only the water pump , otterstat, or fans....or one huge internal head gasket leak.

[Nicholas R]

It is overheating on the freeway? I don't think you should ever need your fans on the freeway. The air flowing from the driving is much more than your fans will provide. It's definitely something to do with your coolant flow. Like othes have said, likely a lot of air.

[RoyHinkley]

Easy to try.
Check connections at plugs going to radiator fans, mine were loose and that was what was keeping the, from turning on. I think those connections fail more often that the actual otterstat.
Worth a shot to try jiggling them and seeing if the fans kick on. If you put the ac to max ac it will try to run the fans, its a good way to check without having the car reach temp.

[RoyHinkley]

If you see flow of coolant in the expansion tank then your H2O pump is working.

[Michael]

If you see flow of coolant in the expansion tank then your H2O pump is working.

Not necessarily

[DMCMW Dave]

It is overheating on the freeway? I don't think you should ever need your fans on the freeway. The air flowing from the driving is much more than your fans will provide. It's definitely something to do with your coolant flow. Like othes have said, likely a lot of air.

Overheating on the freeway (assuming the system is full, bled, etc.) but not around town is a good sign of the beginnings of a blown head gasket. Or a plugged radiator.

I agree - the fans are not needed (and will not even come on unless you have the A/C on) at highway speeds until you get to about a 90deg ambient.

[RoyHinkley]

Not necessarily

Michael, what else would cause the coolant to show a rapid flow in the expansion tank if the water pump isn't pumping?
Your "not necessarily" needs more info to be clear. Requesting that info please.

[Michael]

Michael, what else would cause the coolant to show a rapid flow in the expansion tank if the water pump isn't pumping?
Your "not necessarily" needs more info to be clear. Requesting that info please.

A water pump may work at lower demands, but not be able to flow enough coolant at upper rpm levels due to a worn or broken impeller.

[RoyHinkley]

A water pump may work at lower demands, but not be able to flow enough coolant at upper rpm levels due to a worn or broken impeller.
Yes, true. I thank you for the clarification.:thumbup:

[Ryan S.]

Thanks everyone for your suggestions and recommendations
Uggg.... I really hope it's not head gasket. Only thing I did about a week ago was to replace a working otterstat with a hot climate otterstat. I may have introduced air while I was replacing otterstat.

But I have been driving it over a week and didn't have any issues. Even 20miles driving in the Saturday morning, temp was fine. Just slightly over the first line. It overheated on the way back to 220f

I checked oil and it looks normal.

Just pressure tested coolant and no leaking. 15 psi for 10 min and held pressure.

I jumped otterstat wires and fans are working. So it's not fan nor wiring. I tried other working otterstat and still no fan through otterstat.

How do you know if radiator is plugged?







Overheating on the freeway (assuming the system is full, bled, etc.) but not around town is a good sign of the beginnings of a blown head gasket. Or a plugged radiator.

I agree - the fans are not needed (and will not even come on unless you have the A/C on) at highway speeds until you get to about a 90deg ambient.

[NightFlyer]

How do you know if radiator is plugged?

Usually by a pressure build up when running that will dump coolant out of the over-flow hose on the header bottle, assuming that the system is filled to capacity.

If you want an easy way of purging air from the system, jack the rear end of the car a good 3.5 feet in the air, and support it with two jack stands. Make sure that the coolant level in the header bottle is sufficient, if not over-filled. Then start the car with the rear end up in the air. Let it run up to temp, watching the temp gauge and waiting for the fans to kick on and cycle. If temp hits 220F before the fans kick on, turn the engine off. Check the level of coolant in the header bottle, and top off as necessary. After allowing the car to cool down. Start up and run up to temp again. Keep doing this until the car won't take any new coolant into the system (and hopefully the fans come on and cycle as they should). The car will purge the air in the system out via the header bottle and replace the air with coolant. Hopefully this solves your problem.

Best of luck! :thumbup:

[DMCMW Dave]

How do you know if radiator is plugged?

Everything else tests good and the car overheats at high speed.

It is difficult to flow-test a radiator because the pressures involved are extremely low. The water pump is not a positive displacement pump, and if the radiator is plugged it acts just like sort-of bad thermosts, i.e. the water just goes back in the engine. A conclusive test is to remove the radiator and force water through it, and compare the flow to a new one.

If the car has a history of poor maintenance, goop in the cooling system, etc. it's likely, but overall a relatively rare problem.

[David T]

Everything else tests good and the car overheats at high speed.

It is difficult to flow-test a radiator because the pressures involved are extremely low. The water pump is not a positive displacement pump, and if the radiator is plugged it acts just like sort-of bad thermosts, i.e. the water just goes back in the engine. A conclusive test is to remove the radiator and force water through it, and compare the flow to a new one.

If the car has a history of poor maintenance, goop in the cooling system, etc. it's likely, but overall a relatively rare problem.

One possibility is the suction hose to the water pump is collapsing during periods of high flow (highway driving). There should be a spring in it to prevent that. I would still suspect air in the system or maybe a bad thermostat. Pressure test the radiator cap on the header tank.

[Ryan S.]

I pressure tested coolant at 15 psi for 25 min. Lost 1 psi due to a small leak around otterstat. Otherwise no other significant leak.

Stupid questions. Could air be introduced through otterstat replacement?

Should I flush the coolant system? Would that help open up any clogs?

What I still don't understand is how otterstat is not kicking in. Far as I can tell, otterstat should be working. Could air in the system cause otterstat to malfunction?

Also my coolant system self bleeder should prevent this kind of thing from happening, right? I leave the shut off valve open so that system bleeds air constantly.

Thank you

[Rich]

...no other significant leak.
Could air be introduced through otterstat replacement? Not very much of it. That fitting is below the level of the header tank, which is full of coolant, so the coolant will drain out that fitting when you pull the 'stat out and little, if any, air will go in.

Should I flush the coolant system? Would that help open up any clogs?

What I still don't understand is how otterstat is not kicking in. Far as I can tell, otterstat should be working. Could air in the system cause otterstat to malfunction? Only if there is a lot of air. As would be the case if it was low on coolant and now it isn't, right?

Also my coolant system self bleeder should prevent this kind of thing from happening, right? I leave the shut off valve open so that system bleeds air constantly. I don't know. Do know that with a stock setup the Otterstat does what it needs to do.

Answers inserted above.

Additional note - it helps if the Otterstat pipe is oriented so that the Otterstat is on the bottom of the pipe. In this orientation any coolant going past it will be in contact with the sensor.

Your original symptoms were for a system that seemed to be very low on coolant. Now that you've topped it up and after you assure the 'stat is on the bottom it should perform fine.

Let us know if the problem persists.

[DMCMW Dave]

Here's another test. Let the car idle until hot, i.e. when the gauge reads when you'd expect the fans to come on (just short of 220 on most cars, but there is a tremendous amount a variation as to what is "normal" from car to car. Touch the pipe with the otterstat and see if it's warm (hot).

Jump the otterstat wire so that the fans turn on. Put a hand behind the radiator (NOT IN THE FAN BLADES) and see if you have hot air coming out of the fans. Check them both If the air is cold, you don't have coolant flow. If it is, the otterstat is probably bad.

Unfortunately the otterstat itself is kind of a POS part. If the car is ever overheated, OR you happened to drop the otterstat on the ground in the process of installing it, it's probably bad.

Yes, air can be introduced during otterstat replacement, especially if you let a lot of the coolant run out. I can swap one and lose maybe a few ounces, in that case air did not get in.

As for the bleeder we strongly recommend that it be run closed most of the time. Open it after service, heat cycle it a few times, and then just leave it closed. The theory, if you will, is that if you leave it open it will do exactly what you expect and keep bleeding air out of the engine. That's fine, but air should not be getting into the engine in the first place. If you have the bleeder closed in normal operation, you'll get a HOT reading much earlier (before the system is truly empty) and you will know you have a problem. If you leave it open and have the beginnings of a leak somewhere, you will not know you have a problem until it's so low that the bottle is empty and the engine is more dangerously overheated. Look at the gauge as a bit of an early warning system in a normally operating cooling system.

[Ryan S.]

Rich, thanks for answering my questions. That helps a lot.
Dave, that is a great idea!!! I will give it a try tomorrow after work. And your explanation about self bleeder makes sense. I will leave it closed now on

thank you!!!

[David T]

Rich, thanks for answering my questions. That helps a lot.
Dave, that is a great idea!!! I will give it a try tomorrow after work. And your explanation about self bleeder makes sense. I will leave it closed now on

thank you!!!

I understand you tested your system, I suggested you pressure test the radiator cap. If it does not hold pressure that can cause the car to overheat.

[Ryan S.]

I understand you tested your system, I suggested you pressure test the radiator cap. If it does not hold pressure that can cause the car to overheat.

That's easy to do and I should do that to make sure.
David, Thanks for a good suggestion.

[Ryan S.]

Everything else tests good and the car overheats at high speed.

It is difficult to flow-test a radiator because the pressures involved are extremely low. The water pump is not a positive displacement pump, and if the radiator is plugged it acts just like sort-of bad thermosts, i.e. the water just goes back in the engine. A conclusive test is to remove the radiator and force water through it, and compare the flow to a new one.


So could it be a case of failed thermostat? Is there an easy to way to test thermostat?
Thank you

[DMCMW Dave]

So could it be a case of failed thermostat? Is there an easy to way to test thermostat?
Thank you

Yes.

If the otterstat pipe never gets hot, it means:

--no coolant in engine (common :shameful:)
--thermostat stuck closed (kind of rare)
--failed water pump impeller (extremely rare)

The only conclusive test the thermostat is to remove it from the car and put it in a pan of hot water and see if it opens.

[Ryan S.]

Thanks Dave!!!

[David T]

Yes.

If the otterstat pipe never gets hot, it means:

--no coolant in engine (common :shameful:)
--thermostat stuck closed (kind of rare)
--failed water pump impeller (extremely rare)

The only conclusive test the thermostat is to remove it from the car and put it in a pan of hot water and see if it opens.

Or you have coolant but the water pump is full of air. If you have a blown head gasket it can happen.

[DMCMW Dave]

Or you have coolant but the water pump is full of air. If you have a blown head gasket it can happen.

If the water pump is full of air there isn't much in the block and the heads will be dry. At any rate, my point is that the water would not be circulating.

[David T]

If the water pump is full of air there isn't much in the block and the heads will be dry. At any rate, my point is that the water would not be circulating.

It is possible with a blown head gasket for air to collect in the thermostat and water pump to the point where it won't circulate water. If you don't open the bleeder or have a self-bleeder the water pump can't pump air. The header tank may even look full and the block can be full of coolant too. Point is you have to get the air out of the system for it to work. If you keep getting air in the system you either have leaks where coolant is getting out or you have a blown head gasket (or maybe both!).

[Some guy]

I had a problem with my car that was self imposed. I was not getting the air out of the lines. On most front engine cars you bleed the coolant till a little fluid comes out.

On my Delorean;

Make sure you have something keeping the boiling coolant from hitting you face and skin

When i bleed the air out of my cooling system, i have everything cold to start. I fill up the coolant. Then i run the car with the bleeder open. Coolant will come out very soon. I wait till it is almost a stream coming out before i close the bleeder valve. i wait till the thermostat is hot and the system has coolant through it. it will spit coolant and air as it is warming up. flushing out the air takes a little long then a chevy or other front engine car.

Then once it cools back down i refill the coolant bottle. I always over fill it (not on purpose) then i will see the over flow spit the coolant onto the exhaust.

Again
Make sure you have something keeping the boiling coolant from hitting you face and skin

[Ryan S.]

Yes.

If the otterstat pipe never gets hot, it means:

--no coolant in engine (common :shameful:)
--thermostat stuck closed (kind of rare)
--failed water pump impeller (extremely rare)

The only conclusive test the thermostat is to remove it from the car and put it in a pan of hot water and see if it opens.

Dave
You are good. :notworthy::notworthy:
I am shame to admit that it was #1. Not enough coolant and my stupidity. I may have drained a little too much when I was bleeding coolant through radiator and didn't refill the tank. Eventually coolant got lower and air got into the system and also air and not enough coolant kept otterstat from working.

I added another 1/2 gal and bled the system. I made sure enough coolant was in the tank. Otterstat kicked in and fan turned on. Otterstat pipe was hot and I felt warm air behind fans. I drove it around town and temp was at slightly above the first line. Thank god.

I really appreciate everyone's help on this. You guys are amazing and this is what I love about this forum. :grouphugg:

[Ryan S.]

Well.... I spoke too soon. I am on a side of freeway, cooling off my car right now. I decided to drive it to work this morning. Everything went fine until 10 miles from home and I noticed the temp gauge going up. Eventually it was reaching 220 and then almost to 240. I pulled over to the side freeway and checked coolant level and it's full. Fan came on and otterstat pipe is hot. I am not sure what is going on with mine.
:facepalm:

[Ryan S.]

26402

[DMCMW Dave]

.... and checked coolant level and it's full. Fan came on and otterstat pipe is hot. I am not sure what is going on with mine.
:facepalm:

Unfortunately that sounds like the typical head gasket symtom. Once it's cooled off try bleeding the engine - if it's full of air again that's likely the issue. There is a device you can attach to the coolant bottle and test for exhaust gas in the coolant.

[jmettee]

A quick but telling test: smell your coolant at the header tank. Does it smell like coolant or like exhaust/old engine oil?

I had a condition where I was slowly loosing coolant & collecting air in the radiator, but never really running hot or mixing oil & coolant. Over time, my coolant didn't get oily like a badly blown head gasket, but the coolant did smell like used oil from the exhaust gas. I apparently had a leak path from the upper cylinder into the coolant chamber that allowed exhaust gas into the cooling system. It baffled me for a while, but a exhaust gas coolant check confirmed it was happening.

[Ryan S.]

:mecry:

[Rich]

Unfortunately that sounds like the typical head gasket symtom. Once it's cooled off try bleeding the engine - if it's full of air again that's likely the issue. There is a device you can attach to the coolant bottle and test for exhaust gas in the coolant.

Good idea. This is one such gadget:

http://www.summitracing.com/parts/lil-75500

A shop may run a quick test for you if you can't get one of these soon enough.

Hoping you get a negative reading.

[Ryan S.]

Thanks Rich. Yes, I hope it's negative. I checked oil and it looks nice and brown. Coolant tank doesn't smell like oil. I bled some more air through radiator. Raised rear of car to bleed through thermostat housing.

Tonight, temp got to 220F but otterstat wouldn't kick in. Otterstat pipe felt very hot but no fan. I turned fans on by using AC. Air didn't feel warm at all. I bled radiator and coolant was cool. Shouldn't it be hot? It seems like no coolant is going through otterstat pipe. Thermostat failure?

[jmettee]

Thanks Rich. Yes, I hope it's negative. I checked oil and it looks nice and brown. Coolant tank doesn't smell like oil. I bled some more air through radiator. Raised rear of car to bleed through thermostat housing.

Tonight, temp got to 220F but otterstat wouldn't kick in. Otterstat pipe felt very hot but no fan. I turned fans on by using AC. Air didn't feel warm at all. I bled radiator and coolant was cool. Shouldn't it be hot? It seems like no coolant is going through otterstat pipe. Thermostat failure?

Otterstat pipe can get hot from the catalytic converter/exhaust being nearby. I like to feel the hose that leaves the waterpump on the left side & attaches to the otterstat pipe. It gets warm in just a couple minutes. BEST: check the pipe going into the top of the radiator (drivers side) after a while to see if it's warm. It'll take longer to feel hot since the coolant cools along the length of the car, but that pipe should be pretty warm when the engine gets up to normal temp or after a short drive.

All the thermostats I've ever witnessed failed in the open position (temp never really gets warm on the gauge), but they can also fail closed. That is the cheapest/easiest solution to throw money at in an attempt to resolve your problem....& rule out that part as being a problem. At your current state, I would do this....as well as take the otterstat to a pot of hot water with a multimeter & see if the switch functions at all.

[Ryan S.]

Thanks Justin. That sounds like a good idea. I didn't think about otterstat in a hot water test. I have a bleeder installed by the top of radiator and coolant came out was not warm at all when car was at 220F. I will check the hoses on driver side today to see if gets hot or not.

Is it difficult to remove thermostat? Would this involve replacing some gaskets or parts?
thanks again

[jmettee]

Thanks Justin. That sounds like a good idea. I didn't think about otterstat in a hot water test. I have a bleeder installed by the top of radiator and coolant came out was not warm at all when car was at 220F. I will check the hoses on driver side today to see if gets hot or not.

Is it difficult to remove thermostat? Would this involve replacing some gaskets or parts?
thanks again

The gasket is actually more of an o-ring around the perimeter of the thermostat itself as opposed to being a sandwich gasket on the 2 housing surfaces. IIRC, you have to take the 3 bolts off the throttle spool/bracket & set it aside before removing the thermostat housing.

What I would do is take out the otterstat & thermostat at the same time. Use a CLEAN container & drain the cooling system at the radiator drain to minimize what drains out of the otterstat pipe & thermostat housing. It's the least messy way to do it....but you will definitely have to purge air from the system when closing up & refilling.

Perhaps Dave S can chime in, but I know there are otterstats with different temp settings. What I don't know is if the temp setting is on the otterstat itself. Regardless, a boiling pot of water (212F) should be high enough to diagnose both the otterstat & the thermostat functionality.

[NightFlyer]

When you overheat, I don't recall you ever mentioning puking coolant or steam via the overflow on the header bottle. Did you check the pressure cap on the header bottle for proper spring operation? Should be a 15lb cap, and you should be able to easily compress the spring with your hand. If you have doubts, they're cheap to replace.

May as well backflush the system, as this will let you know if the radiator is plugged or not. Here's the procedure I personally like to use when backflushing and refilling the system, for what it's worth:

http://dmctalk.org/showthread.php?7919-My-Delorean-VIN-3305-coming-to-Italy!!&p=125964&viewfull=1#post125964

Best of luck!

[Rich]

Thanks Justin. That sounds like a good idea. I didn't think about otterstat in a hot water test. I have a bleeder installed by the top of radiator and coolant came out was not warm at all when car was at 220F. I will check the hoses on driver side today to see if gets hot or not.

Is it difficult to remove thermostat? Would this involve replacing some gaskets or parts?
thanks again

You are reporting that the rad fans blow cold when you run them off the A/C and the temp gauge is >220F. That's new and interesting info. Thanks.

This points to the problem being something else besides or additional to the otterstat. Test the otter if you like but when it works the radiator will still be cold when the engine is hot, so you have something else going on besides the otterstat. So you are sure the radiator really is cold/cool when the engine gauge is >220F?

I'd set the otterstat test aside for now. You need to get hot coolant up to the radiator before worrying about the fans pulling any heat out of the coolant up there.

Unranked poss. causes, all of which are somewhere in this thread now....

Low coolant (below water pump level) due to leak (perhaps head gasket)
Restriction in coolant circuit (t'stat not opening or radiator clogged or...) you haven't bottomed out anywhere and crushed a coolant pipe, right?
Water pump failure or belt failure/slippage

If the coolant level hasn't gone low again (header tank still normal?) that would be a good start. Plus the head gasket hydrocarbon test. The thermostat isn't too tough to get out and in - as long as the bolts don't break.

I'd try to rule out the head gasket before going much further because you don't need to take anything apart to do it and nothing else will matter if that test is positive.

[Ryan S.]

Thanks guys. I performed the otterstat test and both main and spare otterstats are working. I also had a couple of bad ones and they were indeed broken. So I can rule out fan and otterstat.

Rich, you are absolutely right. So I ordered a coolant combustion test kit and should be here tomorrow. I will find out for sure.

[Bitsyncmaster]

I had one overheating issue once. My car never had any problems until I took it off the autotrain on my trip to DCS-12. As soon as I got my car on the road to Orlando my temp gauge was showing much higher than normal. It did not get very bad on the highway drive but lucky the hotel was just off the highway. All I did was open the bleeder on the thermostat cover and the problem has not showed up since.

I'm guessing the very steep angle driving onto and off of the autotrain moved some air in the cooling system where it never was.

So I now will do a bleed every so often (never did that before). Also put some never seize on those bleeder threads since it was frozen when I first bleed it in Orlando.

[Ryan S.]

I understand you tested your system, I suggested you pressure test the radiator cap. If it does not hold pressure that can cause the car to overheat.

Thanks David T. My pressure tester didn't work right/fit with my radiator cap. (Don't buy MityVac coolant pressure tester from Amazon) I went to Autozone and they confirmed with their pressure tester that my old cap has a slight pressure leaking issue. Got a new $6 cap.

Received UVIEW 560000 Combustion Leak Tester from Amazon today. Followed the direction and tested coolant tank. Test result came back negative. Tested multiple times with engine on and off and color stayed the same- BLUE. :yesss: Best $60 I ever spent.

Bled more air from radiator, refill more coolant, and repeat. A lot of air came out from radiator initially. Test drove about 10 miles. :driving1: Temp stayed at 200F mark mostly on freeways and slightly above on local streets. Otterstat kicked in correctly and felt hot air coming from fan. I think it is working now. I hope.

[Ryan S.]

Situation
Overheating continues. After yesterday's successful test drive, I decided to test drive again this morning. Mostly freeway driving for 4 miles. For about 2 miles, temp reached at 210 and when I got home (4 miles), it was at 220F mark. Fan came on at around 215F. I was too afraid to drive it too far from home. I repeated the test drive in the late afternoon and got the same result.


Background

:what_the:On April 5, car over heated to 225F on freeway. When I got home, I've noticed that fan didn't kick in at high temp.
:cool: April 8, Issue Resolved. Refilled coolant and bled the system. Test drove the car for 10 miles and performed fine. Temp stayed at slightly above 200F mark.
:what_the::what_the:On April 10, car over heated to 240F on freeway (10 miles). Fans didn't kick in. Coolant level was normal.
:cool:On April 12, Issue Resolved. Tested car for coolant combustion, tested otterstat, refilled coolant and bled system again. Replaced coolant cap. Test drove car for 10 miles and the car performed fine. Temp stayed at 200F and Otterstat/Fans kicked in when temp reached at 215F.
:what_the:On April 13, car over heated to 225F after 4 miles of freeway driving. Otterstat/fan kicked in. Driver side upper radiator pipe felt hot and fan air felt warm but not hot. 2 hours later, raised rear and try to bleed engine (t'stat) with engine on. Temp reached at 220F but otterstat/fan didn't kick in. Otterstat pipe felt hot to touch but upper radiator pipe (driver side) felt slightly warm or normal.



Assessment

So far this is what I know.

Otterstats are (main and spare) working. Passed boiling water test.
Fan is working. Air from fan was warm (not hot) when car was at 220F on
Coolant has been bled multiples times through Toby's self bleeding system (via T'stat and bled manually through upper radiator hose)
Coolant cap has been replaced with 16 PSI cap from Autozone yesterday. Quality seems low and fit is not very tight compare to the old cap.
Coolant combustion test was negative. Tested multiple times in different conditions.
Fan belts are all working. Belt <2 months old.
Water pump was replaced by PO about 2 years ago
No noise from water pump
Coolant pressure test - 14 PSI to start. 11 PSI after 20 min. Small coolant leak through Otterstat.
Header tank level full
Unable to find any collapsed hoses or other major coolant leak


For some reason, Otterstat is not working consistently due to lack of coolant in Otterstat pipe. I don't think radiator is the problem since hot coolants are not even reaching radiator. Not even reaching otterstat, I don't think. I have ruled out head gasket with the coolant combustion test.

So I am guessing that I have intermittently working thermostat or water pump. What do you think? Any recommendations?

[NightFlyer]

Situation
Overheating continues. After yesterday's successful test drive, I decided to test drive again this morning. Mostly freeway driving for 4 miles. For about 2 miles, temp reached at 210 and when I got home (4 miles), it was at 220F mark. Fan came on at around 215F. I was too afraid to drive it too far from home. I repeated the test drive in the late afternoon and got the same result.


Background

:what_the:On April 5, car over heated to 225F on freeway. When I got home, I've noticed that fan didn't kick in at high temp.
:cool: April 8, Issue Resolved. Refilled coolant and bled the system. Test drove the car for 10 miles and performed fine. Temp stayed at slightly above 200F mark.
:what_the::what_the:On April 10, car over heated to 240F on freeway (10 miles). Fans didn't kick in. Coolant level was normal.
:cool:On April 12, Issue Resolved. Tested car for coolant combustion, tested otterstat, refilled coolant and bled system again. Replaced coolant cap. Test drove car for 10 miles and the car performed fine. Temp stayed at 200F and Otterstat/Fans kicked in when temp reached at 215F.
:what_the:On April 13, car over heated to 225F after 4 miles of freeway driving. Otterstat/fan kicked in. Driver side upper radiator pipe felt hot and fan air felt warm but not hot. 2 hours later, raised rear and try to bleed engine (t'stat) with engine on. Temp reached at 220F but otterstat/fan didn't kick in. Otterstat pipe felt hot to touch but upper radiator pipe (driver side) felt slightly warm or normal.



Assessment

So far this is what I know.

Otterstats are (main and spare) working. Passed boiling water test.
Fan is working. Air from fan was warm (not hot) when car was at 220F on
Coolant has been bled multiples times through Toby's self bleeding system (via T'stat and bled manually through upper radiator hose)
Coolant cap has been replaced with 16 PSI cap from Autozone yesterday. Quality seems low and fit is not very tight compare to the old cap.
Coolant combustion test was negative. Tested multiple times in different conditions.
Fan belts are all working. Belt <2 months old.
Water pump was replaced by PO about 2 years ago
No noise from water pump
Coolant pressure test - 14 PSI to start. 11 PSI after 20 min. Small coolant leak through Otterstat.
Header tank level full
Unable to find any collapsed hoses or other major coolant leak


For some reason, Otterstat is not working consistently due to lack of coolant in Otterstat pipe. I don't think radiator is the problem since hot coolants are not even reaching radiator. Not even reaching otterstat, I don't think. I have ruled out head gasket with the coolant combustion test.

So I am guessing that I have intermittently working thermostat or water pump. What do you think? Any recommendations?

Just to correct you on one thing - raising the rear end helps to bleed the radiator and heater core, but not the engine (the way I drain and refill the system is what prevents air from getting trapped in the engine/pump).

Sounds to me like the thermostat needs to be changed. I recommend one that operates at the stock/OEM standard of 180F, as opposed to a hotter one (which is popularly done to push the fuel system into a closed loop quicker and keep it operating in a more consistently closed loop lambda operation, and while doing this shouldn't necessarily hurt anything, I also don't think that the PRV was designed/engineered for such even though it should tolerate it just fine).

If you're concerned about potential blockage somewhere in the system, then you might also want to backflush and refill the system while doing the thermostat, but that's up to you to decide.

Best of luck!

[Ryan S.]

Yes, you are correct. It's not engine. My bad.
Yes, I better call Julee and order a new thermostat today. I agree. I should do backflush and refill. I am just glad that it's not head gasket. By the way, in order to take out a t'stat, do I have to remove W pipe first?
Thanks

[NightFlyer]

Yes, you are correct. It's not engine. My bad.
Yes, I better call Julee and order a new thermostat today. I agree. I should do backflush and refill. I am just glad that it's not head gasket. By the way, in order to take out a t'stat, do I have to remove W pipe first?
Thanks

Having never done the thermostat on my car, I can't say for sure, but it sure looks like doing so would give you better access / room to work.

Best of luck!

[Bitsyncmaster]

So your fans seem to be intermittent. Wonder if you have an intermittent relay ground.

[NightFlyer]

So your fans seem to be intermittent. Wonder if you have an intermittent relay ground.

Good point Dave - never even crossed my mind. Worth checking out. That's why you're the electrical guy :biggrin:

Of course, that still wouldn't explain why the hoses and radiator didn't feel noticeably warmer with significant increases in the engine temp, but a stuck / malfunctioning thermostat, bad water pump, or plugged lines would. If there's decent flow into the header bottle while running from the heater core return, then one would presume that the pump was functioning properly, although that's not always quite true either, as Michael pointed out - but without actually being able to test pressure / flow rate at various point in the system, it's the best indicator that we have to work with.

Thus, if I were in this boat, I'd be replacing the thermostat and completely backflushing and refilling the system, as a backflush will provide you with a way to diagnose any blockage. If after, and the lines/rad checked out as being OK, and he's still having problems, then I'm afraid that it's probably water pump time.

[David T]

What radiator do you have? If it is old it may be plugged up with dirt on the air side or deposits on the water side. Is there a license plate in front of the grill? Any blockage can make the motor overheat, especially at speed.

[Ron]

I recommend one that operates at the stock/OEM standard of 180F, as opposed to a hotter one (which is popularly done to push the fuel system into a closed loop quicker and keep it operating in a more consistently closed loop lambda operation, and while doing this shouldn't necessarily hurt anything, I also don't think that the PRV was designed/engineered for such even though it should tolerate it just fine).

FYI/FWIW- The manual calls for 185-192F (A:01:01)

[Rich]

Situation
Overheating continues. After yesterday's successful test drive, I decided to test drive again this morning. Mostly freeway driving for 4 miles. For about 2 miles, temp reached at 210 and when I got home (4 miles), it was at 220F mark. Fan came on at around 215F. I was too afraid to drive it too far from home. I repeated the test drive in the late afternoon and got the same result.


Background

:cool:On April 12, Issue Resolved. Tested car for coolant combustion, tested otterstat, refilled coolant and bled system again. Replaced coolant cap. Test drove car for 10 miles and the car performed fine. Temp stayed at 200F and Otterstat/Fans kicked in when temp reached at 215F.
:what_the:On April 13, car over heated to 225F after 4 miles of freeway driving. Otterstat/fan kicked in. Driver side upper radiator pipe felt hot and fan air felt warm but not hot. 2 hours later, raised rear and try to bleed engine (t'stat) with engine on. Temp reached at 220F but otterstat/fan didn't kick in. Otterstat pipe felt hot to touch but upper radiator pipe (driver side) felt slightly warm or normal.


For some reason, Otterstat is not working consistently due to lack of coolant in Otterstat pipe. I don't think radiator is the problem since hot coolants are not even reaching radiator. Not even reaching otterstat, I don't think. I have ruled out head gasket with the coolant combustion test.

So I am guessing that I have intermittently working thermostat or water pump. What do you think? Any recommendations?

That is a great list of your data so far, Ryan. Very nice. I bolded a couple of interesting points.

So at the moment do we have this situation?
a. There is coolant flow at least some of the time (hot upper hose at radiator)
b. The cooling fans do not always run when they should (April 12 they did. April 13 they did not.)
c. April 12 and 13 were similar weather days in your area

While you might have an intermittent otterstat you might have some other intermittent component (relay, ground, thermostat).

The key is to figure out whether the problem is related only to a fan operation problem or, more basic, a coolant flow problem (which in turn can also cause a fan operation problem if hot coolant isn't hitting the o'stat).

One other test you might try, one that could at least rule out the thermostat:
With the A/C off repeat your latest trial drives again and again until you seem to be getting the overheating problem.
Turn the A/C on, which has the effect of driving the fans regardless of what the otterstat is telling them to do.
See if the overheating continues or not in that mode during the test. Do verify that when you hit the A/C the fans do indeed come on in any condition first.

If the A/C-on remedies it then the coolant flow is probably OK. Focus on the o'stat circuit.
If the A/C-on makes no change then something is keeping enough hot coolant from getting circulated.

Keep up the good data-taking work! You will solve this problem.

[Rich]

And, setting aside my previous post about data-taking, if you are tired of testing stuff then of course throwing a new thermostat in regardless of its temp range will rule the t'stat in or out....

Depends on how systematic you like to be.

I don't know much about thermostats but would be surprised to find one that worked one day, then didn't, then a day afterward worked fine. Still, they are pretty cheap and they go in fairly easily on this car.

[NightFlyer]

FYI/FWIW- The manual calls for 185-192F (A:01:01)

Yeah, I was actually just reading the manual last night (preparing to do some work on my car) and noticed that after I had posted my comment. I pulled the 180F number from an old post that Dennis made. 180F was by far the standard of most makes/models that were using engines designed/engineered in the '70's, as the PRVs were. Whatever the actual stock/OEM thermostat that actually came in the car was rated at (which isn't necessarily what's stated in the manual or what DMCL was providing as a replacement), that's what I'd personally be opting for in my car if/when I have to change mine out.

[Ron]

180F was by far the standard of most makes/models that were using engines designed/engineered in the '70's, as the PRVs were. Whatever the actual stock/OEM thermostat that actually came in the car was rated at (which isn't necessarily what's stated in the manual or what DMCL was providing as a replacement), that's what I'd personally be opting for in my car if/when I have to change mine out.Yeah, 180 was the standard (oil vascosity, clearance, etc.) until O2 sensors/ECUs etc. came along...and 190-191 became the rule of thumb (else ruff idle etc.) . Then to help get it into closed loop even quicker, they added a heater to the O2 sensor. The engines manual shows three types, I-III, (178-181°F), (187-190°F), (196-199°F). I use a 191 myself since it is in spec, I don't want the temp lower in the winter here, and, none of them have much at all to do with upper temp/overheating. Preference, after a point, in any case.

[jawn101]

Ryan - yes, you'll need to remove the W pipe to get the thermostat out. That's just 5 bolts, and then I believe you will have to remove the throttle assembly (2 bolts and not as hard as it sounds at all) and then 2 more bolts to remove the thermostat housing. Be *very* careful not to strip the bolts into the thermostat housing as the housing is NLA through normal channels.

[DMCMW Dave]

Don't take the throttle assembly apart. Just disconnect the bottom link (like a door strut) and take out three bolts holding it to the manifold. Set it aside and don't mess with the cables at all. When you put it back on start all three bolts with your fingers before you tighten anything.

[jawn101]

Don't take the throttle assembly apart. Just disconnect the bottom link (like a door strut) and take out three bolts holding it to the manifold. Set it aside and don't mess with the cables at all. When you put it back on start all three bolts with your fingers before you tighten anything.

Good clarification, thanks Dave! I've done it so many times I don't even think twice, but you're right - remove the quadrant arm (don't lose that little tiny clip into the valley!) and the whole thing just comes right off the manifold.

[NightFlyer]

Yeah, 180 was the standard (oil vascosity, clearance, etc.) until O2 sensors/ECUs etc. came along...and 190-191 became the rule of thumb (else ruff idle etc.) . Then to help get it into closed loop even quicker, they added a heater to the O2 sensor. The engines manual shows three types, I-III, (178-181°F), (187-190°F), (196-199°F). I use a 191 myself since it is in spec, I don't want the temp lower in the winter here, and, none of them have much at all to do with upper temp/overheating. Preference, after a point, in any case.

But in the late '70's and early '80's, they started sticking 02 sensors/ECUs and higher thermostats on engines and systems that were specifically engineered/designed around the lower temp standard, as opposed to re-engineering/re-designing the engine and components to specifically accommodate such changes. As I said before, while 20F shouldn't make a huge difference and the engine should be able to tolerate it just fine, it could potentially lead to some premature wear of engine internals / system components (plastic header bottle, anyone). And by raising the floor, it reduces the amount of headroom you have should you ever find yourself experiencing an overheating condition because of something else being potentially faulty in the system.

My Northstar powered Cadillacs have a normal operational temperature of 220F, but the engine was specifically engineered/designed to run that way.

Off topic, but Smokey Yunick's hot vapor engine had a normal operating temperature of 400F-440F, always running just shy of complete thermal meltdown.Tolerance for overage was nil.

[Ryan S.]

Thanks guys for your helpful information and suggestions.
To answer David T's questions: Yes, I believe it is an original radiator and no, I don't have a front license plate.
To answer Rich: Yes, I have tried AC fan test when car was over heating and didn't lower the temp.

At this point, I suspect that I have a randomly open and closing t-stat. Today, I test drove it again and it ran like a champ. Same 4 miles route and it never over heated. Drove another 10 miles with just a hair above the first line. Checked driver side radiator hose and it was very hot and fan air was warm to hot.

Julee is sending me a new t-stat. I hope.... that will do the trick.

[NightFlyer]

Thanks guys for your helpful information and suggestions.
To answer David T's questions: Yes, I believe it is an original radiator and no, I don't have a front license plate.
To answer Rich: Yes, I have tried AC fan test when car was over heating and didn't lower the temp.

At this point, I suspect that I have a randomly open and closing t-stat. Today, I test drove it again and it ran like a champ. Same 4 miles route and it never over heated. Drove another 10 miles with just a hair above the first line. Checked driver side radiator hose and it was very hot and fan air was warm to hot.

Julee is sending me a new t-stat. I hope.... that will do the trick.

Much more likely to have an intermittent thermostat than an intermittent water pump, unless the belt was loose or slipping or the pump pulley was seizing - but both of those are issues separate from the pump. Thermostats can get plugged with crud and/or rusted semi-frozen - they are a wear item, despite being relatively reliable.

Best luck and I hope the change solves your troubles!

[hmcelraft]

After reading through your troubles I was reminded of a similar issue I had last year. I change hoses and coolant. Before that everything was working and cooling fine. However, after the engine warmed up and I drove it a while. It seemed that I could not get circulation and it acted like air was still in the system. I bleed some out and in a few hours there would be no circulation again. This went on for DAYS. I did a combustion test - no issue (whew). Everything else seemed ok. After some head scratching and standing around looking at things - I noticed that I had the return hose attached to the pump with the bend arched to a point higher than the metal return hose line. I squished it a few times and found air in it. My conclusion was that there was no way to get trapped air out of that line with the hose in that position and the air in that spot was causing the lack of circulation. I turned it down to a lower point so air could not get trapped there again. I had turned it higher to move it away from the alternator belt but moved it a lot higher unnecessarily. I've had no issues since then. I do check the line ever now and then just to see if there is air hose but so far so good. No over heating and everything seems normal.

FYI and maybe more on point with your issue - I also observed in an issue I had with my everyday car that has a thermostat like that of the DeLorean. The thermostat was sticking on that car - sometimes the car would show hot - sometimes cold - never too much either way (close) but wide swings. That "wafer" on the bottom of the thermostat has to go down all the way when hot to get maximum coolant from the radiator. Also if by some chance the "wafer" has broken off you will not get circulation. The wafer has to be the proper size and the thermostat has to move the specified ranges during operation for proper circulation. Good you're getting a new thermostat from a reliable source. My point is - if the thermostat is stuck or partly stuck - it can cause the lack of proper circulation, or adequate circulation, you have described.

[David T]

After reading through your troubles I was reminded of a similar issue I had last year. I change hoses and coolant. Before that everything was working and cooling fine. However, after the engine warmed up and I drove it a while. It seemed that I could not get circulation and it acted like air was still in the system. I bleed some out and in a few hours there would be no circulation again. This went on for DAYS. I did a combustion test - no issue (whew). Everything else seemed ok. After some head scratching and standing around looking at things - I noticed that I had the return hose attached to the pump with the bend arched to a point higher than the metal return hose line. I squished it a few times and found air in it. My conclusion was that there was no way to get trapped air out of that line with the hose in that position and the air in that spot was causing the lack of circulation. I turned it down to a lower point so air could not get trapped there again. I had turned it higher to move it away from the alternator belt but moved it a lot higher unnecessarily. I've had no issues since then. I do check the line ever now and then just to see if there is air hose but so far so good. No over heating and everything seems normal.

FYI and maybe more on point with your issue - I also observed in an issue I had with my everyday car that has a thermostat like that of the DeLorean. The thermostat was sticking on that car - sometimes the car would show hot - sometimes cold - never too much either way (close) but wide swings. That "wafer" on the bottom of the thermostat has to go down all the way when hot to get maximum coolant from the radiator. Also if by some chance the "wafer" has broken off you will not get circulation. The wafer has to be the proper size and the thermostat has to move the specified ranges during operation for proper circulation. Good you're getting a new thermostat from a reliable source. My point is - if the thermostat is stuck or partly stuck - it can cause the lack of proper circulation, or adequate circulation, you have described.

Another unusual cause for overheating is if you get a thermostat that has no "weep" hole in it. On the Delorean, because you must be able to bleed the air out, you MUST have a weep hole so the air can get past a cold thermostat. Usually the hole will have a piece of loose metal in it to act as a check valve but it isn't necessary. In fact, if there is no hole you can just drill a 1/16" hole in it. I agree, at this point you either have air in the system or a bad thermostat. Since you mentioned you still have the old radiator, I would change it too. At the very least, when bleeding air, you should loosen the small hose on the top, right tank to get as much air out as you can. You must be VERY gentle with that hose, the plastic barb on the tank is brittle and can break off easily.

[Ryan S.]

One of the memebers suggested that I check the cap fitting on coolant bottle. Sounded like he had a problem keeping pressure due to a defective coolant bottle construction. Is there a good way to test to make sure coolant bottle with cap on is keeping the pressure??? My new cap feels lose and not sure if it is sealing the coolant bottle or not. This is probably not the main cause of problem but could be the reason for elevated coolant temp when weather gets hot.
Thanks

[Grover]

One of the memebers suggested that I check the cap fitting on coolant bottle. Sounded like he had a problem keeping pressure due to a defective coolant bottle construction. Is there a good way to test to make sure coolant bottle with cap on is keeping the pressure??? My new cap feels lose and not sure if it is sealing the coolant bottle or not. This is probably not the main cause of problem but could be the reason for elevated coolant temp when weather gets hot.
Thanks

The imperfections caused my radiator cap rubber to gouge and never seal perfectly. I kept slowing spitting coolant out and my cooling was never as good in the summer as it was on a cool day. Turned out that the imperfections never let the cap seal entirely, raising my coolant temperature and never allowing my system to properly pressurize.

26603
26604

[Ryan S.]

http://img.tapatalk.com/d/14/04/17/ymasu4u4.jpg
Fortunately mine looks a bit better. Never the less, my cap feels not tight enough so I borrowed your idea and added another layer of rubber gasket from an old cap. My cap now feels very tight. For the last three nights, my car has been running like a champ. Especially tonight after the cap mod, car was running exceptionally well. Freeway temp was below 200f line and otterstat kicked in much earlier. And just by fan, temp dropped down to below 200f mark. My car has never ran this cool before. Thanks Steve!!!

[DavidProehl]

Coolant pressure test - 14 PSI to start. 11 PSI after 20 min. Small coolant leak through Otterstat.




Fortunately mine looks a bit better. Never the less, my cap feels not tight enough so I borrowed your idea and added another layer of rubber gasket from an old cap. My cap now feels very tight. For the last three nights, my car has been running like a champ. Especially tonight after the cap mod, car was running exceptionally well. Freeway temp was below 200f line and otterstat kicked in much earlier. And just by fan, temp dropped down to below 200f mark. My car has never ran this cool before. Thanks Steve!!!

That did it? I would have never thought a slightly leaky cap (3 PSI lost every 20 min of resting) would have caused overheating like this. This one certainly had me confused. Very glad this is resolved! What a nightmare to troubleshoot.

[jawn101]

[/LIST]



That did it? I would have never thought a slightly leaky cap (3 PSI lost every 20 min of resting) would have caused overheating like this. This one certainly had me confused. Very glad this is resolved! What a nightmare to troubleshoot.

I have to agree with David... I don't think the cap is enough to cause this. Unless it was such a poor fit that it was the source of the air getting into the system, and in fact the air pockets were causing the overheating. I'd still keep a very careful eye on things for a while, and make sure everything is 100% bled.

[Rich]

.....I borrowed your idea and added another layer of rubber gasket from an old cap. My cap now feels very tight. For the last three nights, my car has been running like a champ. Especially tonight after the cap mod, car was running exceptionally well. Freeway temp was below 200f line and otterstat kicked in much earlier. And just by fan, temp dropped down to below 200f mark. My car has never ran this cool before. Thanks Steve!!!

Very happy to hear there is some relief on this one, Ryan. Hope it continues this way.

Can you clarify your fix? Did you add a second layer of rubber to the original one (now running with 2 layers)? Or did you cut off the original rubber, then add new rubber such that there is now one layer in the cap, same as before?

Will voice a concern if you are running 2 layers.

[Ron]

Will voice a concern if you are running 2 layers.:hihi2:

[Ryan S.]

Yes, I have 2 layers now. I was able to remove a layer from an old cap and was able to put it in between the metal plate and the original layer.
Hmmmm... come to think of it, this might impede the pressure release??? Is that your concern?

Anyways, overheating came back. Last couple of days, car temp went above 220. Otterstat did kick in but well after 220. I received a new thermostat from DMCMW but haven't had a chance install it this weekend. Too busy. Will try next week.

[Rich]

Thanks for confirming you are running as much as 2X thickness on the pressure cap seal now - as a temporary trial/fix.

Yes, as you guessed, this has the effect of raising the pressure of your system above the setpoint because when the cap is seated on top two seals instead of just one the relief spring is displaced a bit further than it's designed to be. The result is that the cap may then hold pressure above 15 PSI which could cause something else to leak prematurely. Not sure how much higher it will run than 15 PSI but it's not necessarily the same as it was when it was new.

See how soon you can get a new cap on it.

And good luck with the thermostat job.

[jawn101]

It's amazing how different these cars can be. Mine *never* goes more than a hair past the 160 mark (second tick) and the one time it got anywhere near 220 I freaked out. And even that only happened because I smogged the car on a 110 degree day, so it sat idling in that heat for almost an hour in the parking lot of the smog place.

[Ryan S.]

Replaced T'stat yesterday and drained coolants. It wasn't too difficult. Water pump looked ok but the inside of hoses and pipes looked nasty. Unfortunately, both old and new thermostats passed the boiling water test. So my problem might not be T'Stat, unless old one happened to work randomly.
I am going to flush radiator this weekend and see if that is going to solve the problem. Fingers crossed.

[dn010]

You will know if your cap is defective because your system will be unable to build or maintain good pressure - squeeze on the hoses when the system is cold and then squeeze when its warmed up and you'll see the difference. When mine was getting too hot, I'd squeeze on the hose and they had no pressure leading me to the cap. Even a slightly leaky cap will cause issues, it will seal one minute and then release pressure below the intended PSI the next, so your gauge will stay cool then dart to hot, then suddenly back to cool - back to hot (I'm only speaking from my experience).

Unfortunately, my car will NOT stay cool without the second rubber piece which was done in probably 2003 and has given me no issues whatsoever 11 years later. I don't have a concern with the pressure being too great that the cap will not release - since there is an issue with my filler neck not at the correct height, the second piece of rubber makes up the difference and the cap (I believe) is still near the correct height in order to still release. This was confirmed when I broke a belt and when I made it to a gas station, I found coolant pouring out of the vent hose - luckily it was winter and the car didn't get hot AND I always carry spare belts :biggrin: BUT again this was my situation 11 years ago and while I doubt there is a high rate of defected stainless coolant tanks these days - it's still worth a try to rule that out.

[Ryan S.]

Replaced t-stat and flushed coolant system, multiple times. My OCD kicked in and decided to clean coolant tank and sight tube. Unfortunately, I ruined coolant tank in the process but Hervey offered to fix it for me. Put in my old plastic coolant tank as temporary measure.

At first try, coolant boiled over and fan failed to kick in. Ugggg.... Very depressing moment. I am thinking.... I give up. Cleaned engine area, refilled coolant and bleed some more. Drove around the block and temp stayed normal range and fan kicked in.

Next day, tried it again. Drove more and even on freeway. Temp stayed normal and fan kicked in.

Today, tried it once more. Temp stayed normal and fan kicked in. I hope this continues. Still nervous about driving it to work. Fingers crossed.
:thumbup:

[NightFlyer]

Replaced t-stat and flushed coolant system, multiple times. My OCD kicked in and decided to clean coolant tank and sight tube. Unfortunately, I ruined coolant tank in the process but Hervey offered to fix it for me. Put in my old plastic coolant tank as temporary measure.

At first try, coolant boiled over and fan failed to kick in. Ugggg.... Very depressing moment. I am thinking.... I give up. Cleaned engine area, refilled coolant and bleed some more. Drove around the block and temp stayed normal range and fan kicked in.

Next day, tried it again. Drove more and even on freeway. Temp stayed normal and fan kicked in.

Today, tried it once more. Temp stayed normal and fan kicked in. I hope this continues. Still nervous about driving it to work. Fingers crossed.
:thumbup:

Sounds like there may have been ample air remaining in the system the first time you tried it.

But after that, it's sounding good - here's hoping for ya! :thumbup:

[Rich]

So with perhaps still an intermittent cooling problem can you report any details since you buttoned up the system?

a. Is it really, really topped up and bled? As of now it seems the answer is "yes".
b. When the engine is warmed up is the feed hose to the radiator warm/hot (coolant flow is OK)? Probably, since it seems to be running OK the last couple of times. Still, it's easy to check to be sure about it. The hose up there should be nearly as hot as the hose coming off the engine when everything's steadied out.

Good luck with it. If all continues to go well then it was perhaps a clogged radiator and maybe a leaky cap as root causes.

[Ryan S.]

Thanks guys for your support.
Yes, I think I bled it well.
Yes, the feed hose was hot and when I bled through passenger side top radiator hose, coolant was hot also.
I think so, it could have been a clogged radiator, bad cap, or t-stat. I am just glad that it wasn't a head gasket. I will drive more this weekend and see.

[Grover]

Because you replaced the coolant bottle with the original plastic one before it started working, I would not count out the possibility of the coolant tank causing some of the issues.

How was the tank ruined by you cleaning it? Also, when you get a replacement and put it back in, let us know if the issue is still corrected.

[hmcelraft]

So many cars these days require this method I'm surprised no one has mentioned it - or - if they I have, I've missed it. Less than $50 for a tool to do it with if you have an air compressor.

[NightFlyer]

So many cars these days require this method I'm surprised no one has mentioned it - or - if they I have, I've missed it. Less than $50 for a tool to do it with if you have an air compressor.

Or you can just jack the rear end about 3 feet in the air while filling the system with new coolant and use a purged continuous flow pump of some sort (I use an old fuel pump) to fill the entire system via the heater core return line in the engine bay. Make sure that you fill the system until the header bottle is overfilled, and with the car still having its rear end in the air, start it and run it up to temp (until the thermostat opens and the fans kick on and off). Then stop it and refill the header bottle as needed. Repeat running up to temp, turning off, and topping off the header bottle until the level in the header bottle no longer changes or it begins to puke/purge excess coolant that it doesn't want from the system. Then you can lower the car and go for a good 20 mile test drive, as your cooling system should be good to go and air free, all without touching a bleed valve/nipple. It's how I refill my system after a flush, and I never had to remove a hose from the radiator or touch a bleed valve/nipple, and my car has always run at around 180F, never getting any hotter than 195F.

[NightFlyer]

it could have been a clogged radiator, bad cap, or t-stat.

A bad cap would merely change the boiling point of the coolant. If you were running pure water, the boiling point without any pressure on the system at all (presuming a completely failed cap) would still be 212F - a temp that you really don't want to see your PRV getting to regardless. Thus, I don't think it was the cap.

Clogged radiator is a possibility, but that wouldn't explain the luke warm inflow hose while the engine was burning up.

While the old thermostat tested good, in reality, its operation may have been impeded by crud/scale build up. Also possible that you were constantly getting air into the system from running the coolant level in the header bottle too low. And it's still possible that the issue lied/lies with your water pump. Any of these things are where I'd look for fault before looking at a bad cap or plugged radiator, given the evidence that you've described.

Again, hoping that the flush, refill, and new thermostat have things all sorted for you :thumbup:

[Rich]

Clogged radiator is a possibility, but that wouldn't explain the luke warm inflow hose while the engine was burning up.


Hmmm. Maybe it would explain it, no?

Anything that restricts the coolant circulation, assuming the coolant level is at least up to the pump level and the pump is operating, could create that condition. The hot coolant in the engine would not flow to the clogged or partially clogged radiator at a normal flow rate (one symptom being a lukewarm inlet hose to radiator and, if the radiator is completely clogged, then coolant up front never gets warm), leading to an overheating engine. Removing the restriction, whether it was due to Ryan's flush job, the t'stat replacement, or anything else, would allow the flow of hot coolant to the radiator - normal operation.

Why his overheating symptoms originally seemed to come and go may remain a mystery. Assuming the symptoms are gone for good.

[Ryan S.]

Today, I decided to drive my D to Bay Area (round trip 170 miles) for a business meeting. I felt very nervous about driving a very long distance after what happened a few weeks ago, stranded on freeway. (PTSD) But I had to try it. And I made sure I have my AAA card in my wallet.
Morning drive went well. Outside temp was at around 65F. Car temp stayed at 200F most of the way. I am thinking, :yesss:.

However, coming back was totally nerve wrecking. :nervous: Outside temp was at around 95F and plus a heavy traffic. Whenever car temp was hovering at 215F, I am mentally preparing for a worst case scenario and ready to pull over. But fortunately, it went back down to 210F. When I turned on the AC, I could see temp going up a few degrees but never got to 220F. I think car performed well. Fan always kicked in at the right moment and brought temp down. thank god. :notworthy:

I am just curious, what is the normal car temperature when outside is 95 or 100F?

[DMCMW Dave]

Today, I decided to drive my D to Bay Area (round trip 170 miles) for a business meeting. I felt very nervous about driving a very long distance after what happened a few weeks ago, stranded on freeway. (PTSD) But I had to try it. And I made sure I have my AAA card in my wallet.
Morning drive went well. Outside temp was at around 65F. Car temp stayed at 200F most of the way. I am thinking, :yesss:.

However, coming back was totally nerve wrecking. :nervous: Outside temp was at around 95F and plus a heavy traffic. Whenever car temp was hovering at 215F, I am mentally preparing for a worst case scenario and ready to pull over. But fortunately, it went back down to 210F. When I turned on the AC, I could see temp going up a few degrees but never got to 220F. I think car performed well. Fan always kicked in at the right moment and brought temp down. thank god. :notworthy:

I am just curious, what is the normal car temperature when outside is 95 or 100F?


That's probably within normal range. There is a pretty substantial variation in temp gauge accuracy from car to car.

[Ryan S.]

Thanks Dave!!!
Always appreciate your helpful advices and supplying me with right parts. I wish your shop was here.