Overheated my car today

[Rich_NYS]

I know there's plenty of threads on overheating, but I'm posting before searching 'cause I think I might've caused the overheat and believe I have a few clues.

I was looking for an oil leak; I degreased the driver's side and front of the engine, hosed it, then blew compressed air in the same area before starting.

The fans didn't come on & the car overheated (I noticed when the coolant overflowed.) I felt one of the coolant pipes at the front of the car and it wasn't hot.

First time it happened, so I'm thinking something I did caused it.

Any thoughts?


....I'm going searching now :reading:

[Dangermouse]

How long was it running before you noticed the spilling coolant, and was it cold before you started?

May just be an expansion tank cap problem.

[NightFlyer]

I know there's plenty of threads on overheating, but I'm posting before searching 'cause I think I might've caused the overheat and believe I have a few clues.

I was looking for an oil leak; I degreased the driver's side and front of the engine, hosed it, then blew compressed air in the same area before starting.

The fans didn't come on & the car overheated (I noticed when the coolant overflowed.) I felt one of the coolant pipes at the front of the car and it wasn't hot.

First time it happened, so I'm thinking something I did caused it.

Any thoughts?


....I'm going searching now :reading:

If the pipes aren't warm up front and the car is overheating, it suggests that the system is suffering from lack of proper coolant flow (assuming that there's coolant in the system to push instead of air).

Step 1 - check the coolant level and make sure that you have coolant in the system instead of air. If you let it overheat for an extended period of time, a good amount of coolant probably vaporized out of the system, so you'll want to top off and bleed the system at a minimum. If you have the oem radiator, then I personally suggest lifting the rear as opposed to touching anything on the radiator to bleed the radiator and heater core. You can bleed the pump via the thermostat housing bleed valve/nipple.

Step 2 - check to make sure that you didn't knock the connector/wires off the otterstat. Then make sure that the connection is clean, dry, and making good contact with the switch terminals.

Step 3 - check your waterpump belt/pulley. After your de-greasing, was the water pump belt pulling the pump pulley normally, or was the belt slipping and sliding around on the pulley? Check the belt - does it feel lubricated or like normal? Check the tension of the belt and make sure that its as it should be instead of loose.

The only other things that would cause a lack of flow are a faulty water pump, plugged passage/pipe/radiator, and/or a bad thermostat.

Before you start looking further at the otterstat/fans/etc, first confirm that the system is properly filled, bled, and that you're getting good flow. If you're still having a no-fan situation, then start digging into those things further.

Best of luck in getting it figured out. :thumbup:

[Rich_NYS]

How long was it running before you noticed the spilling coolant, and was it cold before you started?

May just be an expansion tank cap problem.


Hard to recall how long before overheating, I'm guessing at 15-20 minutes.

It was cold before starting.

Thanks!

[Rich_NYS]

If the pipes aren't warm up front and the car is overheating, it suggests that the system is suffering from lack of proper coolant flow (assuming that there's coolant in the system to push instead of air).

Step 1 - check the coolant level and make sure that you have coolant in the system instead of air. If you let it overheat for an extended period of time, a good amount of coolant probably vaporized out of the system, so you'll want to top off and bleed the system at a minimum. If you have the oem radiator, then I personally suggest lifting the rear as opposed to touching anything on the radiator to bleed the radiator and heater core. You can bleed the pump via the thermostat housing bleed valve/nipple.

After your de-greasing, was the water pump belt pulling the pump pulley normally, or was the belt slipping and sliding around on the pulley? Check the belt - does it feel lubricated or like normal?

Ahhh...that's a good thought. Definitely a possibility.


The only other things that would cause a lack of flow are a faulty water pump, plugged passage/pipe/radiator, and/or a bad thermostat.

Before you start looking at the otterstat/fans/etc, confirm that the system is properly filled, bled, and that you're getting good flow. If you're still having a no-fan situation, then start digging into those things further.

I'll definitely do this first, I'll review your "how-to" on bleeding and buying coolant before proceeding.


Best of luck in getting it figured out. :thumbup:

Thanks man!

[NightFlyer]

Ahhh...that's a good thought. Definitely a possibility.



I'll definitely do this first, I'll review your "how-to" on bleeding and buying coolant before proceeding.



Thanks man!

Sorry - I edited my initial comment a little. You may want to review it again for the additions.

[Rich_NYS]

Sorry - I edited my initial comment a little. You may want to review it again for the additions.

Got it...thanks again!

Ya know, the more I think about it, I think you might be right on with the belt slipping. The engine degreaser is pretty slippery stuff and it's highly possible I got it on the belt & pulley.

I need to replace the hoses on the coolant pipes, so I'll do that first then refill & bleed the system.

[AugustneverEnds]

Do yourself a big favor and buy a coolant system pressure tester if you don't have one. These little things save a ton of time and stress. Autozone rents them for an $80 deposit, refunded when you return it, if buying one in not convenient at this time. Good Luck, you'll get this sorted! :cool1:

[Jonathan]

Hey Rich,

Glad to hear you've got your car out and aboot. (hehe, eh)

Not so glad to hear it overheated though.

Was wondering if you know for certain whether the cooling fans up front had been coming on or not before this situation? I mean before the possible belt slipping or something getting bumped. Testing them is pretty easy in terms of forcing them on via the otterstat or your A/C system.

Was just thinking that could help you narrow it down. As mentioned, could be something as straight forward as the reservoir cap not working properly or air in the system. Good to find out how to correct the out of place things as you see them now, but also correct what caused them to get to that point (meaning, bleeding air from the system could fix it if that was the source of the problem, but if that was only a symptom, then the source of the problem could have been the bad cap or bad otterstat or bad fan wiring or something).

[Rich_NYS]

Do yourself a big favor and buy a coolant system pressure tester if you don't have one. These little things save a ton of time and stress. Autozone rents them for an $80 deposit, refunded when you return it, if buying one in not convenient at this time. Good Luck, you'll get this sorted! :cool1:

I recently saw something about using a pressure tester, sounds like a good idea....thanks.



Hey Rich,

Glad to hear you've got your car out and aboot. (hehe, eh)

haha...I took off & now I'm a hoser!



Not so glad to hear it overheated though.

Was wondering if you know for certain whether the cooling fans up front had been coming on or not before this situation? I mean before the possible belt slipping or something getting bumped. Testing them is pretty easy in terms of forcing them on via the otterstat or your A/C system.

Was just thinking that could help you narrow it down. As mentioned, could be something as straight forward as the reservoir cap not working properly or air in the system. Good to find out how to correct the out of place things as you see them now, but also correct what caused them to get to that point (meaning, bleeding air from the system could fix it if that was the source of the problem, but if that was only a symptom, then the source of the problem could have been the bad cap or bad otterstat or bad fan wiring or something).

The fans definitely worked before yesterday. I began the work with the engine cold, so I'm only assuming they were still in working order before I sprayed degreaser, water, & air on the engine. I'll test the fans today, but I'm going to replace the coolant pipe hoses, refill & bleed before starting the engine again.

A bad cap: wouldn't that just release prematurely or not at all? I'm wondering how that would prevent the fans from coming on. I'll likely get a pressure tester, so I'll test the cap at that time.


BTW, are the hose clamps for the cooling pipe hoses 2"?

Thanks!

[Jonathan]

The fans definitely worked before yesterday. I began the work with the engine cold, so I'm only assuming they were still in working order before I sprayed degreaser, water, & air on the engine. I'll test the fans today, but I'm going to replace the coolant pipe hoses, refill & bleed before starting the engine again.

Finding out if the fans come on now as it sits without tinkering with anything else could be some valuable information. Mostly in terms of keeping your troubleshooting/fixing steps separate. If it was the slippery belt affecting the water pump, in an extreme case no coolant is moving and then even with a good otterstat and well working fans, it wouldn't be telling them to turn on. That could explain it perhaps. If the coolant pathway was blocked and explaining the cold pipes upfront, it could take more than a grippy belt to correct.

Finding out if the fans come on at all or in which circumstances seems like a good place to start.


A bad cap: wouldn't that just release prematurely or not at all? I'm wondering how that would prevent the fans from coming on. I'll likely get a pressure tester, so I'll test the cap at that time.

Yea, the bad cap you would think is independent of the fans. Not 100% of the time though, if for example, the temperature at which your otterstat was telling the fans to come on was past the point where the reservoir cap was relieving. Normally, the cap would relieve after 15 psi which corresponds to a certain temperature of the coolant. The coolant could still get past the point where it would flash to steam once pressure is removed entirely. It is supposed to have a boiling point higher than just water at 100 deg C (220 deg F) but if the dilution isn't so great, it could be closer to that of water. When you pressurize it, the boiling point raises (for any liquid). So now if you have a liquid hotter than the temperature it would normally become a gas because it is under some amount of pressure, AND you remove that pressure, i.e. with a bad cap, it will immediately turn to a gas/steam and flash out. That doesn't sound like it's necessarily what happened in your car, but it's possible.

The fans are easy to test by jumpering the otterstat leads and bottle caps are cheap and easy to replace if that's also a concern. If the cap is old, it might just be past it's useful life span.

[DeLorean03]

For a pressure tester, you want the Motorad MT-300:

http://www.amazon.com/Motorad-MT-300-MotoRad-Pressure-Tester/dp/B0067UE6IY

Needs no adapters even on a plastic coolant bottle. You'll have everything you'll need to measure the pressure. Typically, I believe it is 15 PSI for 20 minutes means your coolant system is good.

[Jonathan]

Otterstat jumper wire cooling fan test photo, as mentioned.

26711

[jawn101]

For a pressure tester, you want the Motorad MT-300:

http://www.amazon.com/Motorad-MT-300-MotoRad-Pressure-Tester/dp/B0067UE6IY

Needs no adapters even on a plastic coolant bottle. You'll have everything you'll need to measure the pressure. Typically, I believe it is 15 PSI for 20 minutes means your coolant system is good.

The MT-300 is a great piece of gear. I love mine - rented it from autozone and just never returned it.

[Rich_NYS]

I wasn't able to revisit this until today, but in the meantime I bought some coolant, hose & hose clamps. I also checked the otterstat connections & jumpered it to confirm the fans run (they do.)

Hopefully I'll have the car jacked up tomorrow and start removing hoses. I'm also considering changing the thermostat...is that as much of a PITA as it appears?

[DeLorean03]

I'm also considering changing the thermostat...is that as much of a PITA as it appears?

No. Super easy once you've done it.

Big things are getting the W-pipe off the intake manifold, taking the throttle spool assembly temporarily off, and then removing the water pump thermostat housing.

[Rich_NYS]

No. Super easy once you've done it.

Big things are getting the W-pipe off the intake manifold, taking the throttle spool assembly temporarily off, and then removing the water pump thermostat housing.

Thanks, I saw that W-pipe in the way and wondered how far I need to go to get stuff outta the way.

Do I need to be prepared with any gaskets other than the thermostat gasket?

[dn010]

As far as a bad cap:

When I was driving down the highway one day (when I used to live in upstate NY!) I began to have a sudden overheat situation, only for mine the temp would raise up and then suddenly drop, raise-drop raise-drop. So I pulled over, started searching around the engine bay and under the car being clueless, after a while someone was kind enough to stop and lend me some coolant. I was able to make it home but my issue turned out to be a bad radiator cap- I replaced the cap and again had the same issue. I needed to put 2 rubber disks on the bottom of the radiator cap - I have a SS coolant tank and my guess is the filler neck was added at the wrong height, it will only work with a cap that I have to put a second rubber disk on.

[Rich_NYS]

As far as a bad cap:

When I was driving down the highway one day (when I used to live in upstate NY!) I began to have a sudden overheat situation, only for mine the temp would raise up and then suddenly drop, raise-drop raise-drop. So I pulled over, started searching around the engine bay and under the car being clueless, after a while someone was kind enough to stop and lend me some coolant. I was able to make it home but my issue turned out to be a bad radiator cap- I replaced the cap and again had the same issue. I needed to put 2 rubber disks on the bottom of the radiator cap - I have a SS coolant tank and my guess is the filler neck was added at the wrong height, it will only work with a cap that I have to put a second rubber disk on.

Good to know, thanks. I have a SS coolant tank and I might replace the cap as part of troubleshooting this issue.

[Rich_NYS]

Still having a problem, and here's what I did so far:

I flushed the cooling system using Josh's method with a garden hose on pipe 5 and followed it with air pressure....I had good flow out pipe 18.

I replaced the thermostat and the coolant pipe coupler hoses.

I refilled with hoses 9 & 16 removed until I had fresh coolant coming out pipe 18, then put thos hoses back on and filled the header tank and ran the car. I think I got all or most of the air out; I was able to put about 2.25+ gallons back into the system.

I ran the car until the temp gauge showed about 220; the fans didn't come on and the coolant pipe on the passenger side was cold up front.

The driver's side coolant pipe got lukewarm up front, hose 16 got pretty toasty and it appears the thermostat is opening.

When the car is running I see good flow going back into the header tank.

WTH?

[Jonathan]

Yo,

I shot you an email instead of a forum PM as I wasn't logged in on my phone.

Did you get the no-battery-light situation figured out? As I was saying, that bulb needs to work for the car to charge. Battery, alternator, or something else could be a problem still or could be fine all along, but that warning light must be functional when turning the key to accessories.

I don't know how exactly it may relate to the coolant issue, but it might be related or get fixed with a good battery warning light bulb. Maybe the belt on the alternator is having an affect on the water pump. Maybe the voltage dips down far enough from the car not charging to still keep the car running long enough to heat up the engine but without enough "juice" left to power the fans. Not sure. Stop to fix the bulb first would be my suggestion and then player 1 can continue :)

[Rich_NYS]

I just got your email Jonathan...thanks!


I think I'm making progress with the overheating. I just ran the car for another round and the fans came on; this time I had the heater on to see if I was getting heat, but also realized I might not had the cap on tight.

I'm going to give it another round with the heat off (like it was before) to see if that had anything to do with it. Can having the heat on affect anything other than the cabin temperature? If I recall, all it does [to have the heat on] is open up the little "door" in the "heater core housing" and let the hot air into the ducts.

[Jonathan]

I think I'm making progress with the overheating. I just ran the car for another round and the fans came on; this time I had the heater on to see if I was getting heat, but also realized I might not had the cap on tight.

Not sure what you found when you mention the cap might not have been on all the way, but the SS bottle on my car doesn't seem to have quite the right sized neck to use the cap easily. You seem to need to be close to carving your hand up when removing it or getting it on properly because of the way the grooves are. Like on a bottle of pain killers where you need to press down and twist, the combo I have of bottle plus cap makes it necessary to REALLY push down to get it off the groove and remove the cap completely. I don't recall if tightening it is/was similar, but you might have found something similar in yours.

You also mentioned what can the heat on do other than divert heat into the cabin. I won't comment on that specifically, but a trick to help cool your car down in some conditions is to turn the A/C on. Not really based on heat in or out of the engine via the Freon loop, but instead it's more getting your radiator fans forced on. Assuming you have plenty of Freon and your A/C compressor clutch will clack on when call upon, if your otterstat is toast, you can put it on A/C to force your radiator fans on if they aren't coming on from the bad otterstat. If other electrical gremlins are in there, this might not work, but it's an option down the line if you run out of them temporarily.

[NightFlyer]

Still having a problem, and here's what I did so far:

I flushed the cooling system using Josh's method with a garden hose on pipe 5 and followed it with air pressure....I had good flow out pipe 18.

I replaced the thermostat and the coolant pipe coupler hoses.

I refilled with hoses 9 & 16 removed until I had fresh coolant coming out pipe 18, then put thos hoses back on and filled the header tank and ran the car. I think I got all or most of the air out; I was able to put about 2.25+ gallons back into the system.

I ran the car until the temp gauge showed about 220; the fans didn't come on and the coolant pipe on the passenger side was cold up front.

The driver's side coolant pipe got lukewarm up front, hose 16 got pretty toasty and it appears the thermostat is opening.

When the car is running I see good flow going back into the header tank.

WTH?

First, I just wanted to point out that based on your description, you only backflushed the radiator. To flush the heater core (you could backflush it, but to do so is much more difficult and often not necessary), you have to do so via the header bottle bleed hose, #1 in this image:

http://store.delorean.com/images/Category/large/7-1-3.gif

Flushing the heater core also allows you to flush the pump and to some degree the block/engine.

Anyway, my refill procedure must be followed to the proverbial 't' in order to avoid having to manually bleed the system. The manual says 2.9 US gallon system capacity, although, as I ALWAYS overfill the header bottle, I usually end up using closer to 3.0 - 3.1 gallons of coolant (50/50 water/anti-freeze mix). And my refills are always precise. If I'm not adding 3.0-3.1 gallons, then something is wrong. As you didn't follow the procedure exactly, you'll definitely have to manually bleed the system at the water pump at a minimum.

Based on your description of everything you did, and assuming it's a complete description, then my guess is that ample air was left in the system - especially at the pump and block/engine, heater core, and maybe even in the radiator.

If you want to flush the core/pump/block/engine, then you'll want to do that first, in addition to draining the rest of the system. Then refill as directed - no short cuts.

If you're done flushing though and just want to refill the system and get everything working, then here's what you want to do (no short cuts):

1) Fill the header bottle with coolant to just below where the bleed hose, #1, enters into it.

2) Set the HVAC mode switch to heat or vent.

3) Jack the rear end 3 feet in the air, being sure to block/chock the front wheels with something (piece of wood).

4) Get a hose to connect to the thermostat housing bleed valve/nipple and run into a collection device (clean bucket/container capable of holding at least 3 gallons).

5) Start the car and let it run up to temp. When it gets hot enough to open the thermostat, around 187F, open the thermostat bleed valve/nipple.

6) Remove the header bottle cap so that you can see the coolant level in the bottle - be careful not to burn yourself here. Only do this when the temp is below 212F. Leave the cap off for the remainder of this procedure.

7) Let the car run this way, taking care to add coolant to the header bottle to keep it topped off. If the fans start cycling, great. If not, watch the temp gauge. Obviously, kill the engine if/when it looks like it's approaching an overheat - 220F+ or if coolant starts boiling out of the header bottle. Or kill the engine when you've collected roughly 1.5 gallons of coolant in your bleed receptacle. ALWAYS close the bleed valve/nipple before turning the engine off. Repeat if you think it's necessary (if there's noticeable air or spurting continuing to come from the thermostat bleed hose into your bucket as opposed to a nice steady consistent stream of coolant).

8 ) Lower the rear end.

9) Make sure the header bottle is still filled to just below where the bleed hose enters into it.

10) Take the car for a long enough ride to get everything up to proper running temp and see how it performs. Run the heater while doing this test drive and assess heater performance. If the fans are cycling, great. No matter what, kill the engine if the temp gets up to 220F+. No matter what, pull over and kill the engine approximately 8 minutes after passing around 187F. Check the level of coolant in the header bottle and top if off if necessary. Then drive her home, letting her get nice and hot, and see how she performs.

Report back here.

Best of luck!

[NightFlyer]

The only way that the header bottle cap makes any difference on the system is at temperatures above 212F, which a normally operating cooling system shouldn't be reaching in the first place. And even then, all the pressure does is prevent coolant loss from vaporization at running temperatures above 212F.

[NightFlyer]

Running the heater on your test drive allows you to assess the efficiency of heater core operation and coolant flow through it. It shouldn't effect overall system performance all that dramatically, but does act to slightly cool the system.

[NightFlyer]

BTW, if you don't want to jack the rear end up in the air to bleed the radiator, you can instead pull the bleed hose off the side tank and bleed it manually - but if the radiator is original, you're risking damaging the radiator doing this (which is why I always put the rear end up in the air and NEVER touch the radiator hoses).

[dn010]

I disagree. Doesn't coolant (EDIT: Coolant & water mix) expand when being heated, thus if your cap is bad it will expand to the point of overflow??


The only way that the header bottle cap makes any difference on the system is at temperatures above 212F, which a normally operating cooling system shouldn't be reaching in the first place. And even then, all the pressure does is prevent coolant loss from vaporization at running temperatures above 212F.

[NightFlyer]

Doesn't coolant expand when being heated, thus if your cap is bad it will expand to the point of overflow??

Two ways for a cap to be bad:

1) Incomplete seal or weak spring - vents pressure as opposed to allowing it to build up to the desired limit, in our case 15 psi.

2) Rusted/stuck spring - pressure above the desired limit is trapped in the system, as opposed to being vented from it, causing a potential blowout situation of system components that are not rated/designed to sustain such higher pressures.

The cap is supposed to allow overflow if the system is overfilled or if there's something else wrong in the system causing the temperature/pressure to increase beyond spec/normal, but has no effect on the temperature at which the the system operates.

[dn010]

Right, but we are talking about the effect of a bad cap. A #3 in my case was the cap IS good, but the neck of the stainless tank, like another in this thread; has the wrong height to completely seal with a normal cap.

Bad or not sealing, it will still cause problems below 212F in my opinion.

[dn010]

Also, I might be wrong but I believe they tell you to run the heat these days after doing anything with coolant to remove any air that may be trapped in the heater circuit of the cooling system.

[dn010]

AH! I apologize, I see that you are referring to your procedure, not to a possible cause of overheating while operating! Sorry about that, I missed that part!


Right, but we are talking about the effect of a bad cap. A #3 in my case was the cap IS good, but the neck of the stainless tank, like another in this thread; has the wrong height to completely seal with a normal cap.

Bad or not sealing, it will still cause problems below 212F in my opinion.

[NightFlyer]

Right, but we are talking about the effect of a bad cap. A #3 in my case was the cap IS good, but the neck of the stainless tank, like another in this thread; has the wrong height to completely seal with a normal cap.

Bad or not sealing, it will still cause problems below 212F in my opinion.

Pressure raises the vaporization point of the coolant. If you're not building up sufficient/desired pressure because of a leaky cap, the coolant will vaporize at a lower temp than it would under the correct operating pressure. The system is only going to puke coolant if it's overfilled or if it's overheating. Assuming that the system is filled to normal operating capacity, in an overheat situation, you're already at an unacceptable temperature when the system begins puking coolant because of thermal expansion. Thus, how does the cap come into play in causing an overheat?

Here's where it could potentially make a difference, and now we're getting into fluid dynamics - the pressure could actually assist the efficiency of the water pump in circulating the coolant through the system vs a system operating at atmosphere with little to no pressure building restrictions. The pressure also assists the system in naturally purging trapped air in the system out through the header bottle. This could be especially important in systems that aren't sealed very well, have an aging water pump, etc.

However, given the complexity of our cooling system, with it's many sharp bends and passage reductions, I doubt that the pressure sustained by a properly functioning cap makes a very big difference on a properly bled, tight/sealed system, and optimally operating system, as is evidenced by the fact that you still, or should be getting a strong/forceful continuous stream of coolant into the header bottle via the factory bleed hose even with the cap off and the system depressurized.

If the cap was as important in preventing overheating as everyone is making it out to be, then I shouldn't be able to run my car for an hour without the cap on and the system depressurized, without overheating, right? And yet, I can run my car for hours without the cap on just fine without overheating at all. If the cap was that critical, then I shouldn't be able to do that, right?

I think that the focus on the cap is a case of coincidental association, with the cap being blamed when in fact it's an aerated system that's causing the problems.

That said, having a properly functioning cap does indeed help the system to operate as efficiently and effectively as possible - especially on leaky systems with aged/worn components, so you don't want to completely discount it.

Anyway, that's my $.02, for whatever they're worth...

[dn010]

At idle? Yes, you might get away with it. While actually operating? Take the cap off and see what happens...



If the cap was as important in preventing overheating as everyone is making it out to be, then I shouldn't be able to run my car for an hour without the cap on and the system depressurized, without overheating, right? And yet, I can run my car for hours without the cap on just fine without overheating at all. If the cap was that critical, then I shouldn't be able to do that, right?

[Rich_NYS]

Based on your description of everything you did, and assuming it's a complete description, then my guess is that ample air was left in the system - especially at the pump and block/engine, heater core, and maybe even in the radiator.

If you want to flush the core/pump/block/engine, then you'll want to do that first, in addition to draining the rest of the system. Then refill as directed - no short cuts.

If you're done flushing though and just want to refill the system and get everything working, then here's what you want to do (no short cuts):

1) Fill the header bottle with coolant to just below where the bleed hose, #1, enters into it.

2) Set the HVAC mode switch to heat or vent.

3) Jack the rear end 3 feet in the air, being sure to block/chock the front wheels with something (piece of wood).

4) Get a hose to connect to the thermostat housing bleed valve/nipple and run into a collection device (clean bucket/container capable of holding at least 3 gallons).

5) Start the car and let it run up to temp. When it gets hot enough to open the thermostat, around 187F, open the thermostat bleed valve/nipple.

6) Remove the header bottle cap so that you can see the coolant level in the bottle - be careful not to burn yourself here. Only do this when the temp is below 212F. Leave the cap off for the remainder of this procedure.

7) Let the car run this way, taking care to add coolant to the header bottle to keep it topped off. If the fans start cycling, great. If not, watch the temp gauge. Obviously, kill the engine if/when it looks like it's approaching an overheat - 220F+ or if coolant starts boiling out of the header bottle. Or kill the engine when you've collected roughly 1.5 gallons of coolant in your bleed receptacle. ALWAYS close the bleed valve/nipple before turning the engine off. Repeat if you think it's necessary (if there's noticeable air or spurting continuing to come from the thermostat bleed hose into your bucket as opposed to a nice steady consistent stream of coolant).

8 ) Lower the rear end.

9) Make sure the header bottle is still filled to just below where the bleed hose enters into it.

10) Take the car for a long enough ride to get everything up to proper running temp and see how it performs. Run the heater while doing this test drive and assess heater performance. If the fans are cycling, great. No matter what, kill the engine if the temp gets up to 220F+. No matter what, pull over and kill the engine approximately 8 minutes after passing around 187F. Check the level of coolant in the header bottle and top if off if necessary. Then drive her home, letting her get nice and hot, and see how she performs.

Report back here.

Best of luck!

I just got back from outside w/my kids....it's getting too dark now, but I'll definitely do this tomorrow AM....and I won't shortcut! :thumbup2:

Thanks a bunch,

Rich

[Rich_NYS]

Here's where it could potentially make a difference, and now we're getting into fluid dynamics - the pressure could actually assist the efficiency of the water pump in circulating the coolant through the system vs a system operating at atmosphere with little to no pressure building restrictions. The pressure also assists the system in naturally purging trapped air in the system out through the header bottle. This could be especially important in systems that aren't sealed very well, have an aging water pump, etc.

This is what I was thinking when I mentioned the cap, I had been running it without the cap/periodically removing the cap & watching the coolant level. Each time, the temp would head north of 200 and the coolant pipe up front was cold. When I put the cap on tight & left it, things seemed to normalize.

I'm definitely going to do the bleed procedure you recommended and see what I get for air...


, that's my $.02, for whatever they're worth...

Worth plenty 'round here! :thumbup:


BTW, on the bright side, my louvre repair is going really well & it's gonna look pretty awesome after I paint it.

[NightFlyer]

At idle? Yes, you might get away with it. While actually operating? Take the cap off and see what happens...

While operating, the only difference is increasing the speed, and increasing any associated pressure from such operation, of the water pump. I can rev my engine up or run it steady at increased RPM with the cap off and the only difference is increased speed/turbidity of coolant passing through the header bottle, as would be expected. Would I do this while driving the car on the road - no, because the vibration and movement of coolant in the header bottle from acceleration and stops could cause the coolant in the header bottle to spill out, and thereby causing air to infiltrate the system.

But I have done this before (admittedly not with my DeLorean, as the need never arised):

Fill the system with straight water (no anti-freeze) with a flat cap simply to prevent coolant from spilling out, but creating no pressure on the system. Ran fine and didn't overheat at all, as an otherwise normally operating system shouldn't be breaching 212F.

This is NOT true of modern cars that are designed to normally operate at temperatures of 220F, where the coolant mixture and pressure are critically needed to prevent vaporization of the coolant.

[NightFlyer]

This is what I was thinking when I mentioned the cap, I had been running it without the cap/periodically removing the cap & watching the coolant level. Each time, the temp would head north of 200 and the coolant pipe up front was cold. When I put the cap on tight & left it, things seemed to normalize.

I'm definitely going to do the bleed procedure you recommended and see what I get for air...

In most systems, pressurization isn't critical for effective operation. In our system, it might admittedly be more essential for the sake of maintaining proper system flow (fluid dynamics) - especially where a pump impeller may be severely worn or have decades of scale build up hindering the performance, or small pockets of crud might be hindering flow.

Even though there are no visible leaks, your system probably isn't air tight. I know that mine isn't. And that isn't a problem. The goal is to get the system to do its job efficiently, effectively, and consistently for as little work / new parts as is possible. Which is why the worst thing you can do IMHO is pressure test the system while cold (unless you're ready and willing to start changing everything in the system out), as doing this will actually create leaks that didn't otherwise exist. When the system heats up, everything expands and the rubber becomes more pliable, hence sealing the system as it's pressurized by the thermal expansion of the coolant. To pressure test a cold system (especially one with old parts) isn't realistic and often causes more problems than it solves. There's a post that DMCMW Dave made somewhere where he says essentially the same thing based upon decades of observation. If there's no huge leaks or experienced coolant loss after operation, then you're best to NOT cold pressure test the system.

Lately, it seems like a lot of owners are complaining about not being able to obtain a proper seal between the cap and the aftermarket SS header bottles, despite having run their cars just fine in the past with the same SS header bottle and cap. Either the cap rubber seals are going bad or the necks of the SS bottles are deforming over time with use. Remember that there are two seals that the cap makes - 1) against the flange of the neck, and 2) along the inner walls of the neck (via the gasketed disk that attaches to the end of the spring on the cap). If you're not getting a good flange seal, I'd use a little non-hardening gasket goop as opposed to trying to increase the thickness of the rubber gasket or doubling up the rubber gaskets (as some have tried), as doing so changes the height of where the pressure plate on the cap sits in relation to the overflow outlet on the neck. If you're not getting a good inner wall seal, it's either because the rubber in the cap is old/deformed, or the characteristics of the neck of the bottle has deformed over time. If a prefab cap doesn't create a good inner wall seal, then you may have to modify the cap with a custom cut gasket for this application.

In fact, if you're not getting a good seal, it should technically have more to do with the disk gasket that rides the inner wall as opposed to the flange gasket (despite it getting all the attention). To test to see if you're getting a good seal, you can 1) clean the rubber gaskets in the cap and make sure that they are dry, 2) clean the flange and inner wall of the neck of the header bottle, 3) apply an even layer of SS cleaner to the flange and inner walls of the bottle neck (spay enough onto a paper towel so that's it's milky and apply in an even layer to where the surfaces are milky), 4) install the cap as you normally would, 5) immediately remove the cap by lifting it straight up, and 6) inspecting the rubber on the cap for SS cleaner residue to see if the rubber is making a complete seal against the metal parts of the bottle.

Hope that helps!



BTW, on the bright side, my louvre repair is going really well & it's gonna look pretty awesome after I paint it.

AWESOME :thumbup:

Looks like new and you saved yourself a ton of money - that's what it's all about! :biggrin:

Plus it's awesome when you accomplish something new or that you never before thought that you could do - it's a good feeling and you should take pride in your accomplishments (with humility of course).

A fresh coat of paint really hides the repair - I don't even notice my repair job anymore, unless I'm actively thinking about it when operating the louver. No one ever sees it or points it out (not even DeLorean nerds).

[dn010]

Yes rev your engine, hold it at a specific RPM - BUT you're not under load.

You're not only increasing the RPM but you're also increasing the rate of how fast things heat up. Get in a car, get on a highway and floor it with the the heat on. You should notice that the heat coming from the vents is noticeably hotter. My argument is that you need to have a sealed system, whatever the cap may be - Take your coolant cap off and go for an hour drive and tell me your car does not overheat, and I'll stand corrected.




While operating, the only difference is increasing the speed, and increasing any associated pressure from such operation, of the water pump. I can rev my engine up or run it steady at increased RPM with the cap off and the only difference is increased speed/turbidity of coolant passing through the header bottle, as would be expected. Would I do this while driving the car on the road - no, because the vibration and movement of coolant in the header bottle from acceleration and stops could cause the coolant in the header bottle to spill out, and thereby causing air to infiltrate the system.

But I have done this before (admittedly not with my DeLorean, as the need never arised):

Fill the system with straight water (no anti-freeze) with a flat cap simply to prevent coolant from spilling out, but creating no pressure on the system. Ran fine and didn't overheat at all, as an otherwise normally operating system shouldn't be breaching 212F.

This is NOT true of modern cars that are designed to normally operate at temperatures of 220F, where the coolant mixture and pressure are critically needed to prevent vaporization of the coolant.

[NightFlyer]

Yes rev your engine, hold it at a specific RPM - BUT you're not under load.

You're not only increasing the RPM but you're also increasing the rate of how fast things heat up. Get in a car, get on a highway and floor it with the the heat on. You should notice that the heat coming from the vents is noticeably hotter. My argument is that you need to have a sealed system, whatever the cap may be - Take your coolant cap off and go for an hour drive and tell me your car does not overheat, and I'll stand corrected.

Exactly - but the coolant loss you'd experience from driving an unsealed system on the road is going to be from splash out caused by acceleration/decceleration, vibration, and grading of the roadway, which is what I already stated, and NOT from thermal expansion of the coolant (unless your car is already overheating for some unrelated reason, in which case, you already had a problem). That's my point. Back in the day, I used to run a '72 Buick Skylark with the 350 V8 with a non-pressurized (sealed but constantly vented) cooling system for years and never had a problem with the car overheating, except once when it snapped the water pump belt.

That said, because of the length and complexity of our cooling system, the effect/impact of maintaining a properly pressurized system could actually assist coolant flow throughout the system as a function of basic fluid dynamics (the back-pressure creates a more forceful flow from the pump and also helps to naturally purge air from the system via the header bottle, which has nothing to do with thermal expansion). In a typical short run system, the effect is negligible at best, but in our very long system, the effect could be exponential and thus somewhat essential - especially with aged and semi-constricted components. To be honest, I can't really say for sure. As many owners swear that having a properly functioning pressure maintaining cap actually noticeably lowers the running temps of their cars, then I have to presume this to be true to a certain extent (although I'm also not ruling out the possibility that such observations could be coincidental and not truly directly relational). If you're system isn't air tight, then getting it as close as you can to the 15 psi spec will undoubtedly assist the system in naturally purging any air that may have been introduced to the system when cold.

Thus while the cap isn't critical on an otherwise 'perfect' system, it becomes exponentially more so on an aged system.

#1 most important thing with our cooling system is to always make sure that your coolant bottle is at least half filled (and that your coolant mixture is composed of no more than 60% anti-freeze).

Off topic, but I prefer to use Dex-Cool (the orange stuff) in my system, mixed with a bottle of supplementary corrosion inhibitor and lubricant (but NO system sealers ever), as it seems to cause less wear and leaves fewer sedimentary deposits - especially when left in the system for longer than it should be before being flushed and changed. I know that opinions about Dex-Cool vary greatly - I'm just expressing my personal observations after running it in several aluminum engines (including in my D) since the '90's.

[Rich_NYS]

If you're done flushing though and just want to refill the system and get everything working, then here's what you want to do (no short cuts):

1) Fill the header bottle with coolant to just below where the bleed hose, #1, enters into it.

2) Set the HVAC mode switch to heat or vent.

3) Jack the rear end 3 feet in the air, being sure to block/chock the front wheels with something (piece of wood).

4) Get a hose to connect to the thermostat housing bleed valve/nipple and run into a collection device (clean bucket/container capable of holding at least 3 gallons).

5) Start the car and let it run up to temp. When it gets hot enough to open the thermostat, around 187F, open the thermostat bleed valve/nipple.

6) Remove the header bottle cap so that you can see the coolant level in the bottle - be careful not to burn yourself here. Only do this when the temp is below 212F. Leave the cap off for the remainder of this procedure.

7) Let the car run this way, taking care to add coolant to the header bottle to keep it topped off. If the fans start cycling, great. If not, watch the temp gauge. Obviously, kill the engine if/when it looks like it's approaching an overheat - 220F+ or if coolant starts boiling out of the header bottle. Or kill the engine when you've collected roughly 1.5 gallons of coolant in your bleed receptacle. ALWAYS close the bleed valve/nipple before turning the engine off. Repeat if you think it's necessary (if there's noticeable air or spurting continuing to come from the thermostat bleed hose into your bucket as opposed to a nice steady consistent stream of coolant).

8 ) Lower the rear end.

9) Make sure the header bottle is still filled to just below where the bleed hose enters into it.

10) Take the car for a long enough ride to get everything up to proper running temp and see how it performs. Run the heater while doing this test drive and assess heater performance. If the fans are cycling, great. No matter what, kill the engine if the temp gets up to 220F+. No matter what, pull over and kill the engine approximately 8 minutes after passing around 187F. Check the level of coolant in the header bottle and top if off if necessary. Then drive her home, letting her get nice and hot, and see how she performs.

Report back here.

Best of luck!

I think everything's OK now; I did the procedure above, so far no overheating. I did the bleed procedure about three times, and took before & after pics of my gauge. All three rounds reflect the two pics below, and I did steps 1-7 with the cap off. After the drive, I didn't need to add any coolant. I haven't yet tested the thermostat I replaced, but aside from that I'm still wondering what caused the initial overheat.

Prior to replacing the coupler hoses, I had one or two small leaks (a few drips each time I ran the car while parked.) Do you suppose air got sucked into the system and that was the root cause?

After the pics are a few off-topic comments & questions.

26939

26940




-I think my tires have flat spots that seem to be getting better. Is it possible that over time they'll even-out completely?

-My AC works but I don't hear the compressor come on....is that normal?

-My louvre is ready for painting...just waiting for a 70 degree day!

26941

[NightFlyer]

I think everything's OK now; I did the procedure above, so far no overheating. I did the bleed procedure about three times, and took before & after pics of my gauge. All three rounds reflect the two pics below, and I did steps 1-7 with the cap off. After the drive, I didn't need to add any coolant. I haven't yet tested the thermostat I replaced, but aside from that I'm still wondering what caused the initial overheat.

Prior to replacing the coupler hoses, I had one or two small leaks (a few drips each time I ran the car while parked.) Do you suppose air got sucked into the system and that was the root cause?

Most likely it was air in the system, but it's also possible that something else had just intermittently failed - sometimes you just never know for sure. Just keep an eye on things, but it sounds like you're good to go now :thumbup:

BTW - that's exactly how my cooling system functions, as the fans kick on at about that mark and keep the temp at that level pretty consistently/constantly. As far as I know, that's exactly what you're looking for :cool1:


-I think my tires have flat spots that seem to be getting better. Is it possible that over time they'll even-out completely?

-My AC works but I don't hear the compressor come on....is that normal?

-My louvre is ready for painting...just waiting for a 70 degree day!

26941

It's definitely possible that the tires will continue to even out - especially as it gets warmer out and you start driving the car more. Or they could be shot. Only way to tell for sure is keep driving on them until they're pretty good or you get fed up at them and replace them.

So long as the A/C is working, good for the system. Usually it's not the compressor that you hear, but rather the cooling fans kicking on in conjunction with the compressor cycling. If you're watching for it, you should see a slight voltage dip when that occurs, but if you're running an aftermarket alternator, that too may not be that apparent.

Good deal on the louvre - looks GREAT! I too wish that it would start warming up for us soon. I'm getting sick of having to burn wood at night to keep the house at a nice temperature....

[Rich_NYS]

Most likely it was air in the system, but it's also possible that something else had just intermittently failed - sometimes you just never know for sure. Just keep an eye on things, but it sounds like you're good to go now :thumbup:

BTW - that's exactly how my cooling system functions, as the fans kick on at about that mark and keep the temp at that level pretty consistently/constantly. As far as I know, that's exactly what you're looking for :cool1:



It's definitely possible that the tires will continue to even out - especially as it gets warmer out and you start driving the car more. Or they could be shot. Only way to tell for sure is keep driving on them until they're pretty good or you get fed up at them and replace them.

So long as the A/C is working, good for the system. Usually it's not the compressor that you hear, but rather the cooling fans kicking on in conjunction with the compressor cycling. If you're watching for it, you should see a slight voltage dip when that occurs, but if you're running an aftermarket alternator, that too may not be that apparent.

Good deal on the louvre - looks GREAT! I too wish that it would start warming up for us soon. I'm getting sick of having to burn wood at night to keep the house at a nice temperature....

Thanks for all the help man....!