1G Not your average overheating issue.

[Teancum]

Ok. So I have searched the forums AND google pretty extensively. I have tried everything I can think of or read about and I am still having an issue with my engine overheating. It started a couple weeks ago and the car is now parked pending a solution...
I have a 91 Eagle Talon TSi AWD
I have about a 30 minute commute to work.
The needle starts climbing from the normal range about 20-25 minutes into my commute and its boiling over in the overflow by the time I get to work a few minutes later.

Things I have done/tried:
New thermostat.
New 16lb radiator cap.
Pressure tested the coolant system and fixed 1 pinhole leak.
Compression test. (head gasket is fine)

The fans work as intended.

Please help me figure out what this could be that is causing this overheating!?

 

[luv2rallye]

Have you replaced the radiator? It may just be rusted/corroded/worn out.
Some other ideas: http://www.dsmtuners.com/threads/help-im-overheating-heres-how-to-fix-it.200575/

 

[Teancum]

I have an aftermarket all aluminum radiator... but thanks for the link.

 

[DSM1G90]

Dumb question, but where is the license plate mounted at?

If it dead center of the opening, the plate acts like an air dam pushing the air away from going through the radiator and will cause overheating issues. Found out that one the hard way with a 1G that the plate was mounted in the middle of the opening.
We did the same - new t-stat, cap, flushed out the system....until I saw where the plate was mounted.
Moved the plate and that cured the overheating issue.

How's the WP - new, decent, or needs changing with the belt job?
-DSM

 

[Teancum]

No front plate on it.

And the water pump was replaced when the motor and trans were rebuilt about 8k miles ago... but the car was sitting for almost 5 years so honestly, thats on my list to check.

 

[second_amendment]

have you tried to bleed the system ? Take the cap off and allow it burp the air out, also turn the heater on so it cycles the system. I would double check the water pump since you had it sitting for 5 years.

 

[74runner]

I'd like to add to this ^^^^^.... Open the T-stat cap then start the car and watch for bubbles, if they go away after the T-stat opens (normal operating temp) you had air in the system and that was most likely your problem, if the bubbles never stop you have a blown head gasket...With the heater on full hot does it fade in and out> (Hot to cool/warm)? Don't keep your face over the T-stat while it's runnig, hot coolant can shoot all over the place when it opens

 

[koryto2012]

This. ^ he knows.

 

[74runner]

I saw the part about the head gasket test but! he didn't say any thing about bubbles in the system, easiest thing in the world to check for air in the system by following my previous statement

 

[Teancum]

Thanks for the suggestions guys. I have burped the system every time i add more fluid to it. I havent yet done it with the heater on though. Ill try that tonight. To answer your question... It does stop burping so thats another vote in favor of the head gasket being good.

 

[Teancum]

And thanks for the safety heads up. I would hate to be the one learning that first hand. hahaha. I like to keep my eyeballs away from boiling chemicals...

 

[19jdmdsm91]

The head gasket could still be your culprit. There is no true way to make sure is not the issue unless you the headoff. Do a block test to see if you have combustion escaping into the cooling system. Also how are your afr? Things you can try to help it... water wetter, less ration of coolant to water and drilling 2 holes on the thermostat. Also do you have link? What's your coolant offset set at? Good luck man

 

[DSM1G90]

My little trick to aid in burping the system is: on a new T-stat install, I drill a .050" hole in the flange if there is no jiggle valve. This aid in removing the blocked air under the t-stat and still allows the t-stat to remain functionable.

I had a boilover shortly after I got my Laser (I had already did the belt and pump changeout )and it was a bad one. I though I had also blown a HG, yet had to prove that it wasn't.
Pulled the radiator and pressure washed it out from both ends. That radiator was so full of rust and gunk. With the radiator out and t-stat out, I pressure washed out the block and blew out as much rust as possible.

Put all back together with new t-stat and never have overheating issues again. Water still is nice and green with no hint of rust showing.

-DSM

 

[Teancum]

So I finally resolved this overheating issue. I ended up taking the radiator out and sending it to a shop. there were holes in both header tanks. But some fluke caused the holes to NOT leak till it came to operating temp. even when i pressure tested it cold. Bought a new radiator and its golden. Runs just below the half way point on the OEM gauge. Thanks for all of your suggestions.