Would a clogged heater core cause overheating? I know the heater can cool a little bit when its on, but wouldnt a clogged one have the same effect as having it turned off?

 

Could it be that your air mix system is not good? Like maybe the flap that control hot and cold air is frozen in place or the motor is stuck? When you switch from full cold too full hot on your climat control you can hear the flap move. If it doesn't then thats your problem. I remember reading about a problem with the climate comtrol not working intermittinly due to a bad switch. Just a thought since no one brough it up. Good luck!!

 

I think what you are experiencing with the heater is that when you get low on coolant, air accumulates in the heater coolant circuit. The heater core becomes airlocked.


The heater issue is a symptom of the larger problem.

Good luck.

 

Thanks for all the imput guys. Im gonna stay hopeful and see if an air leak was my problem before I consider rebuilding or buying a used S4NA block. My New filler neck top and rad cap will be here next week to find out for sure.

 

So here's the deal. Fixed all air leaks, bad O-rings and rad cap, and the thing is pumping coolant. No matter what the operationg temps, I get coolant pumped into the overflow. After a 10-15 minutes the temps stay relatively low, but when the coolant level gets lower and lower, the temps gradually low. Oddly enough, if I let it cool down, the coolant is pulled back into the system with little coolant missing. So Ive come to accept my fate and plan on rebuilding as soon as financially possible.

 

Have you considered te fact that your water pump could be toast. i know you have looked at many things but I haven't seen anything about you looking at the pump. mine went out when I drove from GA to TX and I noticed almost no leakage at all. all I got was a low coolant light even when it was full. I looked at everything and noticed a very small leak out of the wheep hole on the pump. A new pump fixwd all my problems. luckily I never over heated. good luck

 

no weepage unfortunately. I wish it was something as cheap as a waterpump. Also, I am getting air bubbles in the filler neck if i crank the engine with the EGI fuse pulled.

 

I've thought about the possibilty of it's a minor cooloant seal leak, maybe converting a 0 psi Evan's NGP set up would buy you some time. I've never tried this yet, but will if I get a bad seal.