Overheat- attempting to post again

[FPBBrandon]

Not sure why the board 403'd my original post, but want to try to repost to get some ideas.

I had 4835 overheat at idle while trying to test another issue, and I didn't notice the car was dropping coolant until it was very hot (full temp gauge). I shut the car down, waited for the block to cool, refilled with coolant and tried to get home from where I was (About 20 minutes.) I made it about 10 before I overheated again, shut down, called a rollback and went home.

The next day, I found a pinhole leak in my return hose coming from the radiator return pipe to the thermostat. I ordered and replaced the hose, refilled with coolant, and idle tested the car. It idled up to 220, the fans came on and it cooled perfectly. I took a friend out on a drive to test it, about 20 minutes of highway driving. The car held temp perfectly on the drive out to the destination. We spent several hours meeting friends, and afterwards, when we fired up the car to go home, I watched the temp gauge slowly creep up to 3/4 on the way home (fans were on), and so I knew I still had a problem. The car did not however go all the way to full heat on the way back, and was hovering at 3/4, which struck me as peculiar.

I tried to bleed the radiator again at this point, but I think I bled it too much and must have let more air in, as the car started moving towards a full overheat again and I got no fans at 220F (I shut down at 3/4).

I have checked the oil breather cap, the mesh is intact. I have checked the coolant, no exhaust bubbles. I have checked the oil, no chocolate milkshake. Other helpful things to note are that my otterstat pipe is pointed down towards the ground, and I am running a metal tank radiator. I am puzzled as to whether perhaps I am bleeding the radiator incorrectly, or if there is another culprit. I am following the reasonably ubiquitous directions posted here;

http://delorean2109.blogspot.com/2008/08/burping-your-new-delorean-baby.html

and haven't seemed to bleed effectively yet. I am puzzled as to why the car held up well temp wise on our drive out and threw an exception on the drive back. While fiddling with the car, I squeezed the outbound to radiator rubber hose, and heard a clicking noise coming from the thermostat housing, which is totally bizarre to me, as far as I can tell, thermostats should not make noise. I am wondering if anyone has advice for next steps. I'm sure with the coolant gusher on the first overheat, I need to take my intake off and go into the VOD for cleaning, anyone have some words of wisdom for other things to pursue?

[skill]

I'd troubleshoot; the otterstat. It could be giving up, poor connection (i.e., wiring), etc. I was thinking perhaps blockage within the coolant system (i.e., pipes, radiator, hoses, etc.). Troubleshoot there and let us know!

http://www.specialtauto.com/delorean-parts/images/otterstat-location.jpg
Photo courtesy of: SpecialTAuto

[dn010]

How old is your water pump & thermostat?

Since the fans are turning on and off I don't think you have a problem with your otterstat, you probably have air in they system though that prevented the fans turning on the most recent time. Are you bleeding at the radiator or using the bleed screw on the water pump?

[FPBBrandon]

How old is your water pump & thermostat?

Since the fans are turning on and off I don't think you have a problem with your otterstat, you probably have air in they system though that prevented the fans turning on the most recent time. Are you bleeding at the radiator or using the bleed screw on the water pump?

Bleeding at radiator. I have an autobleed installed, though I suppose it'd be difficult to tell if it failed. Coolant comes out under pressure on the upper passenger side flange on the the radiator if the car is running, strikes me the water pump shouldn't be the culprit? Car does not have to be hot to shove fluid out though, I thought the T-stat would have to be open.

[dn010]

And the age of your pump/thermostat?

[dn010]

My above question was added prior to you adding additional information in your post #4.

At this point I'd check out the thermostat- it is easy to pull to test and cheap to replace. I believe it does have a small bypass hole in it so you would get some coolant flow to the radiator while cold. If your not sure of the age of the pump you may want to look into replacing it soon - it may work now but as you know they don't last forever.

Not sure if it matters or not but I personally never bled the radiator as described in the link posted. I've had my cooling system apart more times than I'd like to count and the worst I had to do was raise the rear of the car as far up as I could on a jack and open the bleed screw while the engine is running with the heat on full blast. Others have argued it is irrelevant but my engine temp would randomly go high and low which ended up being due to a bad fitting pressure cap on the expansion tank (rather, the expansion tank neck I believe is the culprit). My system would dump coolant out of the coolant tank relief hose or whatever you want to call it, if yours isn't doing that I wouldn't worry about the cap.

So aside from checking out the thermostat, I'd just try to bleed it more - I'd leave the radiator alone, jack up the back of the car letting it run with heat on and see what happens.

Also I'd either pull the hose off the self bleeder or pull whatever nipple is used in place of the bleed screw and make sure there is coolant flow - I've seen that port clog up with junk and prevent fluid from bleeding.

[FPBBrandon]

And the age of your pump/thermostat?

Pump/TStat appear OEM. I will check the high side bleeder next time I get to the car.

[David T]

Pump/TStat appear OEM. I will check the high side bleeder next time I get to the car.

Make sure both fans are working and the fans are secured to the motor shafts and they are pulling air in through the radiator. Make sure nothing is blocking the grill, not even a license plate. If the radiator has green staining it should be replaced. Pressure test the system and replace the thermostat. Test the coolant and if it it is over 5 years old or discolored replace it.

[FPBBrandon]

Make sure both fans are working and the fans are secured to the motor shafts and they are pulling air in through the radiator. Make sure nothing is blocking the grill, not even a license plate. If the radiator has green staining it should be replaced. Pressure test the system and replace the thermostat. Test the coolant and if it it is over 5 years old or discolored replace it.

Both fans are solid, can jumper them to work and also they were working appropriately after the first time I bled. On the attempt to drive home after it boiled over initially, I was on the freeway at speed and the car still overheated. It seems to me if coolant was making it to the radiator, airflow would have cooled it if the fans weren't working. I am thinking its a circulatory problem... Will replace T-stat at the next time I can get back, the car is marooned in Colorado Springs (there's a certain charm to being a grown adult and still getting stuck asking your parents for rides to Denver).

Is there an off the FLAPS shelf thermostat I can use, or is it limited to the vendors?

[dn010]

I was able to go to my local parts store - advance or similar, and get a thermostat. Are you running a stainless coolant bottle from SpecialT with the copper neck painted silver by any chance?

[David T]

I was able to go to my local parts store - advance or similar, and get a thermostat. Are you running a stainless coolant bottle from SpecialT with the copper neck painted silver by any chance?

If it keeps overheating you have to test for combustion gasses in the coolant. You probably blew a head gasket.

[FPBBrandon]

The thought crossed my mind, but there is no coolant-oil swapping going on, and I cant smell any exhaust in the coolant bottle, nor see bubbles with the car running at idle/revs when stationary. A compression test can confirm, but of what I've seen so far, improper circulation is where my thinking was.

I am using the OEM plastic overflow tank.

[dn010]

Along with the water pump & thermostat, I'd add the plastic tank to the list of things to replace. At the very least try a new cap - if the cap is as old as the tank that could be your problem too.

My wife has an Xterra that has a bad head gasket. We have to fill the expansion tank once a week (I know, one day I'll fix it...) otherwise you'd never know there was a problem. You can't see any bubbles in the radiator, nor any smoke when running and no coolant in the oil.

While it is possible you have a bad head gasket with no visible evidence, I'd start with these smaller things and see what happens - they're cheaper and would need to be replaced anyway. I know, I'm trying not to start the "while you're in there, replace this and that" thing, but for reliability if you don't know the age of those things, and especially the aging plastic tank - I'd get them changed soon. They might work great now, but also might leave you stranded- I know my water pump almost did when it died without notice.

[FPBBrandon]

Along with the water pump & thermostat, I'd add the plastic tank to the list of things to replace. At the very least try a new cap - if the cap is as old as the tank that could be your problem too.

My wife has an Xterra that has a bad head gasket. We have to fill the expansion tank once a week (I know, one day I'll fix it...) otherwise you'd never know there was a problem. You can't see any bubbles in the radiator, nor any smoke when running and no coolant in the oil.

While it is possible you have a bad head gasket with no visible evidence, I'd start with these smaller things and see what happens - they're cheaper and would need to be replaced anyway. I know, I'm trying not to start the "while you're in there, replace this and that" thing, but for reliability if you don't know the age of those things, and especially the aging plastic tank - I'd get them changed soon. They might work great now, but also might leave you stranded- I know my water pump almost did when it died without notice.

Cheers. The cap was the first thing to get replaced. I'm thinking a new set of coolant hoses is in order too, they appear to be very old, assuming not original from the metal radiator though. I am assuming the coolant pressure tester is going to reveal lots of leaks.

[David T]

Cheers. The cap was the first thing to get replaced. I'm thinking a new set of coolant hoses is in order too, they appear to be very old, assuming not original from the metal radiator though. I am assuming the coolant pressure tester is going to reveal lots of leaks.

Yes, replacing all of the less costly parts is a good idea but you are wasting money and time. A combustion test is not expensive and will be definitive. The old plastic coolant bottle is not causing the overheat unless it is leaking but it should be replaced along with any other old/worn/bad parts. With all of your posts you are saying it is not some simple, easy to replace item so now you need to think of other, more expensive things. If it isn't a blown head gasket you probably need a new radiator (maybe both).

[FPBBrandon]

Yes, replacing all of the less costly parts is a good idea but you are wasting money and time. A combustion test is not expensive and will be definitive. The old plastic coolant bottle is not causing the overheat unless it is leaking but it should be replaced along with any other old/worn/bad parts. With all of your posts you are saying it is not some simple, easy to replace item so now you need to think of other, more expensive things. If it isn't a blown head gasket you probably need a new radiator (maybe both).

I was unaware of the existence of the combustion test. I will look into doing this at home with an autozone tester.

[David T]

I was unaware of the existence of the combustion test. I will look into doing this at home with an autozone tester.

It is really simple, you draw gases from the coolant system through a liquid and if it changes color it indicates combustion gases being forced into the coolant. You can probably find a local garage that will do it for you and it isn't expensive. Cheaper than buying the equipment. Takes just a couple of minutes. If the head gaskets aren't leaking you can look for other, less expensive causes.

[Ron]

Is there an off the FLAPS shelf thermostat I can use, or is it limited to the vendors?
According to the crossover l (I haven't tried any of them):
Thermostat:
Calorstat: V6569, World: W57-126, Dauphinoise Thompson: 206402-B86

Thermostat Gasket:
GKN: 143-0545, World: W50-194


It might be the sound in the thermostat housing if it as old as you think...

[David T]

According to the crossover l (I haven't tried any of them):
Thermostat:
Calorstat: V6569, World: W57-126, Dauphinoise Thompson: 206402-B86

Thermostat Gasket:
GKN: 143-0545, World: W50-194


It might be the sound in the thermostat housing if it as old as you think...

Be careful with cross/overs. Although they may physically fit they may not work like the original. There is also the problem of the gasket, I doubt you will find it anywhere but a Volvo dealer of a Delorean vendor. Some of the cross/overs I have seen did not have the bleeder hole. Easy to test the thermostat, remove it and heat it up in a pot of water with a thermometer and see when it starts to open.

[Ron]

I agree, that's why I mentioned I haven't tried any of them.

(Wouldn't be surprised if he would be boiling pieces from the sounds of it....;-)