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Discussion Starter · #1 ·
I'm at wit's end with this car. I'll Paypal $20 to the first person who can propose a solution to fix this damn car, or accurately diagnose the problem!

Symptoms:

  • Classic loss of coolant through reservoir tank - only when engine is warm and shut down.
  • Lots of rust in the cooling system apparent - I assume it's from the heater core/coolant loop.

What Works:

  • Heat/AC is good. Hot heat and cold A/C so I think heater core is working, although maybe rusting...
  • Engine warms up nicely, normally and never seems to get hotter than mid-scale.
  • Runs great otherwise, will idle fine with no overflow all day long with the reservoir cap off.
  • Oil looks good - driven about 300 miles or so since this issue surfaced
  • No CEL's, even with EGR Delete

What I've Tried So Far:

  • "Clinton" Heater Core Flush, no change.
  • Replaced OEM Coolant Overflow Tank with Autozone Unit - no change.
  • Head gasket replacement with Fel-Pro (heads vatted and milled)
    • Didn't notice any obvious signs of gasket breakdown on the OEM gaskets.
    • Replaced intake manifold gaskets, exhaust manifold gaskets, oil pan gasket and Injector O-rings.
  • New Motorcraft Water Pump (old one was ok - impeller still intact)
  • New Motorcraft Thermostat (works great, installed correctly)
  • 2 recent coolant flushes, refills with 50/50 Prestone
    • Ran engine with expansion tank cap off
    • tried to burp it by grabbing upper radiator hose when warm (doesn't seem to have air in the system)
    • Let it cool, add coolant, repeat
  • EGR Delete (un-related but I broke the EGR tube - delete works fine)
What I'm going to attempt now:

  • Timing Chain Cover Gasket Replacement
  • New Radiator
  • New Lower Radiator Hose (Radiator Inlet)
  • New Upper Radiator Hose (Radiator Outlet)
  • New Coolant Overflow Hose (Expansion Tank Inlet)
  • New Heater Core Bypass Hose
Does anyone else have an idea of what it could be? The car runs well, and only pukes coolant after driving around with the expansion tank cap on. Mostly only pukes when car is off, but slightly when stopped and idling after driving around. Heater has no effect (not a blockage in the heater core I don't think).

If it's not fixed by these damn methods then I'm driving it off a cliff.

Any ideas on what else it could be? If someone comes up with a $olution I'm sending $20 your way!

B)
 

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im no mechanic (except when fixing the wifes car lol) but have you checked the engine block is not cracked thus resulting in system pressurisation via engine compression.a garage should be able to test for combustion gasses in the coolant, a long shot i know but considering the work/parts youve already changed im scratching my head. hope you get it sorted
 

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Discussion Starter · #4 ·
Just a thought, have you replaced the resevoir cap? And are you overfilling it with coolant?
Yes, sort of. I went from OEM to Autozone. I know the AZ Dorman products are suspect, but the idea here is that the cap's lack of ability to hold pressure allows the coolant to boil right? I don't see this as an issue since the car runs perfect without a cap, no boiling, no increase in level.

Definitely not overfilling - only filled up to "cold" levels, and right now the expansion tank is empty (puked out).

im no mechanic (except when fixing the wifes car lol) but have you checked the engine block is not cracked thus resulting in system pressurisation via engine compression.a garage should be able to test for combustion gasses in the coolant, a long shot i know but considering the work/parts youve already changed im scratching my head. hope you get it sorted
There could be a crack in the block, but wouldn't that mess up my oil? I'm trying to be cheap here, but will a new radiator and hoses that probably is just as expensive as a "proper" diagnoses. I've already been through the hassle of throwing parts at the problem...
 

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Look at the smoke. If it is thick(er) and white, the coolant gets in the cylinders and is expelled as steam. It can get there via a broken head gasket (you replace it) or a crack in the passages around valves (exhaust ones).
But also a crack it might lead to "bubbles" in the expansion tank during running engine - due to pressure, the exhaust gases are pushed in the coolant. That is not boiling water! Can you see that?
Also, in the case of a crack, when the engine stops, the cooland would leak in the cylinders till level drops below crack, and then stop.
You should be able to pull easy a spark plug and check that (smell?) on the front plugs.

If it gets in the oil, the engine oil cap would have a bunch of yellow foam.
 

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im no mechanic (except when fixing the wifes car lol) but have you checked the engine block is not cracked thus resulting in system pressurisation via engine compression.a garage should be able to test for combustion gasses in the coolant, a long shot i know but considering the work/parts youve already changed im scratching my head. hope you get it sorted

i have just been looking around different sites and reading posts with similar problems of over pressurization, main culprits do seem to be either a cracked block or a bad head gasket. in some cases i read people where having the issues even after changing head gaskets. some people where solving this by torquing the headbolts to +10 over the reccomended torque setting. in most cases with either fault cross contamination of coolant and oil was a visible indicator but there was also some posts from people that i read that did not have cross contamination of coolant or oil but did have a bad block/gasket that allowed combustion pressure to seep into the cooling system. i did also read somewhere that supposedly napa does sell some sort of chemical test kit that measures/checks for hydrocarbons in the liquid coolant, if your local auto store has something like that then hopefully it will save you going out and spending on the hoses and other bits before eliminating that possibility.

tony
 

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Discussion Starter · #8 ·
Look at the smoke. If it is thick(er) and white, the coolant gets in the cylinders and is expelled as steam. It can get there via a broken head gasket (you replace it) or a crack in the passages around valves (exhaust ones).
But also a crack it might lead to "bubbles" in the expansion tank during running engine - due to pressure, the exhaust gases are pushed in the coolant. That is not boiling water! Can you see that?
Also, in the case of a crack, when the engine stops, the cooland would leak in the cylinders till level drops below crack, and then stop.
You should be able to pull easy a spark plug and check that (smell?) on the front plugs.

If it gets in the oil, the engine oil cap would have a bunch of yellow foam.
The plugs looked ok when I pulled them last time. I do see a steady stream of coolant flowing in when it's warm. If it's been driven around, I do see the bubbling (see vids).

i have just been looking around different sites and reading posts with similar problems of over pressurization, main culprits do seem to be either a cracked block or a bad head gasket. in some cases i read people where having the issues even after changing head gaskets. some people where solving this by torquing the headbolts to +10 over the reccomended torque setting. in most cases with either fault cross contamination of coolant and oil was a visible indicator but there was also some posts from people that i read that did not have cross contamination of coolant or oil but did have a bad block/gasket that allowed combustion pressure to seep into the cooling system. i did also read somewhere that supposedly napa does sell some sort of chemical test kit that measures/checks for hydrocarbons in the liquid coolant, if your local auto store has something like that then hopefully it will save you going out and spending on the hoses and other bits before eliminating that possibility.

tony
I'll see what NAPA carries to test the coolant/oil/exhaust...

Thanks for the replies and keep them coming!
 

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Bubbles aren't a good thing. I've used the hydrocarbon test kit, we have it as a shop tool at the dealer. Works pissa. Be patient with it though, it may take at least few minutes of revving the engine for the fluid to change color. But with the bubbles you've got there... may not take too long to see hydrocarbons. Good luck.
 

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The plugs looked ok when I pulled them last time. I do see a steady stream of coolant flowing in when it's warm. If it's been driven around, I do see the bubbling (see vids).
In case of a small crack/pore, the spark plugs will be ok, maybe a little black from lower burning temperature. And if the crack/pore is on the back side, you won't see nothing easy :)
Bubbling in the expansion tank with the coolant cold (after you just start the engine) means that exhaust gases are pushed in the coolant. You might be able to smell it.
And of course, once the pressure stops (no more explosions in the cylinders), the coolant will drain thru the same crack/pore in the cylinder.
 

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1) you want to check for a headgasket failure/cracked engine block by using the block tester which you can rent at autozone or buy
Engine Block Internal Combustion Leak Detector Tester on eBay!

2) I have had a similar issue, when I had rust in my cooling system, flushed the cooling system and left just water in the cooling system.

I left the water in because I was going to change the radiator and the waterpump. After I replaced those I went for a test drive, again with just water in the cooling system and it boiled over again. Changed it out for coolant and issue solved.

Are you sure you have a good 50/50 mix?

btw. The rust in the cooling system typically appears after a headgasket failure. The exhaust fumes acidify the coolant and I destroy the antioxidants, leading to corrosion.

You can keep the $20 bucks, because if you have a headgasket issue, you are going to need them :)

edit: I just saw you did the headgaskets, did you also have the heads crack checked?

If you don't see combustion gasses with the block tester, swap out the radiator.
What you could also try is drive it around without a thermostat. I'm not proposing this as a fix, but it would be interesting to see if this would resolve your issues ad maybe help isolate some problems.
 

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I'll take a guess and say it's insufficient heat transfer from the coolant to the radiator caused by deposits/corrosion, possibly complicated by inability of system to maintain pressure because of a leaky overflow tank cap and/or other leak.

Reasoning: 50/50 ethylene glycol mixture won't begin to boil in an unpressurized system until it reaches 220° F. In a system that is at or near 220° when fluid is circulating, when the circulation abruptly stops (when engine is shut down), the thermal energy still in the engine block causes the fluid in the block to absorb the thermal energy to the point where coolant temperature will climb to the boiling point of 220° (called sensible heat) and then flash to steam (latent heat of vaporization) because thermal energy isn't being removed by circulating through the radiator. This steam expansion would then displace any liquid in its way.

If you have marginal radiator performance and/or system pressurization, you might be able to keep the overall coolant loop temperature under 220° while the engine is running and circulating the coolant but once you stop, the temps will rise rapidly, possible to the point where the coolant will flash to steam.

When you have the cap off, the steam can vent from the filler. With the cap on, the steam-displaced fluid is going to leave through the path of least resistance.

Before you tear into the timing cover, replace your radiator if it's old. I would also have the system pressure tested once the new radiator is in place. I think you have to have both of these operating normally to keep steam from flashing. Maybe also up the antifreeze ratio to 55%.

Also check to see if your cooling fan is coming on well in advance of when it starts to really warm up. If your coolant temperature sensor is off, you may not be getting that cooling assist in time to keep temps well below the coolant boiling point.
 

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I know if the coolant is overfilled, it will force its way out past the cap as the coolant expands while the car is running and even after until the engine cools down. What marks are you filling it to? Just trying to get some idea of what it going on. I had a problem of overfilling a Cavalier one time and it kept puking coolant on me.

EDIT: I always pop a small air bleed hole in almost every thermostat I Install. 3/32" would be just fine. In the video it looked like bubbles were coming back into the tank. If you are suspicious that it's combustion gasses, I would run a block test on it. We charge $20 at my shop to run the test on it since the bottle of "tester fluid" costs so much. It will let you know if there is exhaust gasses somehow getting in your coolant though.
 

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Discussion Starter · #14 ·
Thanks for the advice guys - I think I'll try just doing the radiator/hoses for now.

As far as the coolant, I'm filling to the lower "cool" fill line when it's, well, cool.
 

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I think that's a good call

You may also find after pulling the radiator that the air-side is dirty, corroded and otherwise less able to transfer heat to the atmosphere than that of a brand new radiator. With both coolant-side and air-side surfaces insulated against good heat transfer, your radiator may be just barely keeping up.

And, although your temperature gauge looks normal, it may also be reading lower than the real temperature if there is scaling or corrosion on the surface of the sensor.

Putting in a new radiator is a relatively inexpensive and easy replacement task - hope it solves your problem.
 

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I dont believe hoses are going to be the solution. You can disconnect them and see if they are open. But those hoses are so wide that i don't believe they are plugged.

Radiators are btw pretty cheap. About 125 bucks at autozone.
 

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You can also rent a radiator/coolant tester at autozone. You pressurize your system and then watch it for about an hour. If it shows a pressure loss and you don't see anything obvious you pull all plugs and crank the engine. If you have a leak into the combustion chamber it will blow water out of the bad cylinders.

Ed
 

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Thanks for the advice guys - I think I'll try just doing the radiator/hoses for now.
Thst's just pointless if you don't SEE coolant leaking there. If the radiator or hoses where bad, you would loose coolant WHILE the engine is hot and running, because it is most pressurized then, not when you shut down the engine (like you said).
Well, it's your money, have fun!
 

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Not pointless IMHO

The symptoms OP is seeing point to a cooling system that is insufficiently pressurized and/or unable to keep coolant temps in a range where the coolant doesn't flash to steam when the engine is stopped and all that heat has nowhere to go. He mentions that the boilover happens only when he turns off the engine.

A radiator with a lot of internal scaling or corrosion and/or with poor heat transfer from the external surfaces will let the heat content of the coolant rise to where an event like stopping coolant circulation and the resultant inability to exhaust heat to the atmosphere via the radiator (even if impaired, some cooling takes place) will let the coolant reach vaporization stage.

OP is not finding evidence of coolant leaking into oil or combustion spaces and he says he replaced the degas tank so the pressure cap should be working normally . He's already done his head gaskets...

A new radiator will allow the fluid to be adequately cooled while running. I do wonder if the thermostat being used is the right temperature for this car.
 
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