I feel like a Fiat Noobie posting this but.... OVERHEATING!

[ClarkTheShark]

ok so i have a phantom overheating problem that i cant seem to diagnose. I have a 2.0l. Everytime the car sits overnight, it almost seems like all the water mysteriously vanishes from the engine, (not on the ground, not being burnt, not in the oil) causing the car to overheat. I will then pull off the side of the road, take the hose off the t pipe and fill the head back up with water as to rid the car of air bubbles in the head (im familiar with properly "burping a fiat"). The car will then run absolutely perfect at 190f until i stop the car and let it sit overnight. Then when i crank the car again, the problem repeats.

i would like to note that yes i have a brand new thermostat and the fan is functioning properly.

anyone have any ideas?

[azruss]

how is the condition of your overflow tank, hose and radiator cap. sounds like when the motor is cooling down it is sucking air into the coolant system. have heard of people drawing air in thru the heater tube flange.

[narfire]

Any idea as to where the coolant is going? Puddles on the ground? Nope.. check the oil? Nope.. have a look at the heater and passenger side floor. I'd think one could smell any coolant though. When you burped the car, running with the front a bit higher and rad cap off and when the coolant has stopped throwing air out and then the coolant can be seen flowing driver side to passenger side on the top of the rad with the heater valve open. ( I made that mistake and ended up with overheating soon after needing the heat)
So when it sits for a number of hours,the coolant level is low and you end up topping it up. .... coolant gremlins?

[ClarkTheShark]

i would like to add that my heater is not working at all, under any circumstances.

also, my cap and overflow tank appear to be in good shape.

yes when i burp the car i make sure to park it at an upward angle as to let the air release through to front.

What did you say about the engine cooling down and sucking air into it? from the heater flange? is that the one on the firewall? if so, ill bypass my heater core and try from there.

One other comment. I have noticed that the system does not have alot of pressure, (hoses dont get stiff) but my cap is in good condition.

[So Cal Mark]

do you have any means to pressure test the system? Does the car misfire when first started in the morning?

[ClarkTheShark]

do you have any means to pressure test the system? Does the car misfire when first started in the morning?

I have no real means of pressure testing the system. but the engine is not misfiring in the morning or anytime for that matter, and i have no bubbles in the radiator. (tryng to convince myself that my headgasket is OK).

[So Cal Mark]

no misfire when cold is good news, but you really need to pressurize the system to check for leaks. Do you have an air compressor so that you could pressurize each cylinder?

[ClarkTheShark]

no misfire when cold is good news, but you really need to pressurize the system to check for leaks. Do you have an air compressor so that you could pressurize each cylinder?

Yes i do have an air compressor, but i dont think i have the proper fitting to hook it up to the spark plug threads. i do have a cylinder compression guage though.

[kilrwail]

It sounds to me like you have a leak when the system is under pressure, maybe around the heater hoses since you have no heat. Is the overflow tank empty in the morning when you find the system low on liquid? I'd suggest driving the car until the engine is fully warmed up and then inspecting all of the hose connections while the engine is still running (after stopping the car ). Your coolant may be leaking all over town while you're driving, but not in your driveway after shutting the engine off, since the leak is at a high point in the system.

[ClarkTheShark]

It sounds to me like you have a leak when the system is under pressure, maybe around the heater hoses since you have no heat. Is the overflow tank empty in the morning when you find the system low on liquid? I'd suggest driving the car until the engine is fully warmed up and then inspecting all of the hose connections while the engine is still running (after stopping the car ). Your coolant may be leaking all over town while you're driving, but not in your driveway after shutting the engine off, since the leak is at a high point in the system.

I appreciate all of you guys helping me out. This sounds plausible, kilrwail. today after work, im going to bypass my heater core and eliminate that variable.

[azruss]

i had a similar thing with my 80 FI. engine would run fine and clean. I would shut the car down and everything was fine. Go back and look at the car 2 hours later, no issue. look at the car the next morning and plugs 3 and 4 were filled with coolant. so sign of where it comes from. the only thing that made sense was coolant leaking from the seam of the throttle body coolant tank. the flange i was talking about was the heater line that runs under the exhaust manifold and where it connects to the water pump. As others have said the heater valve is notorious for leaking and you dont know it because it has all settled under the drivers side carpet.

[ClarkTheShark]

When you say "throttle body coolant tank," do you mean the little thing with 2 5/16's fittings that sits up on top of the plenum? if so, my engine does not have this.

[azruss]

not suggesting that your problem is the same source, but to point out all the wierd ways you can loose coolant without it being an obvious leak.

[digitech]

I had tiny, pinhole leaks in my heater core - caused an issue very similar to this. I would bypass the core, fill & burp and run it like that for a few days.

[124JOE]

have you guys ever heard of putting an egg white in the rad and running it untill it cooks and plugs the small holes