so ive had this car for about two months now. ive put a new thermostat in it cause it was sticking closed. ive also put a new cap on it. but the problem that im having is. its building to much pressure and popping the cap, filling the the overfill resivor. what im want to know if there is anyone out there that has had this problem and what they did to fix it. im wondering if i have a bad case seal or something along those lines. i really want to get this fixed cause it keeps tripping the add coolant sensor. i can top it off but as soon as i drive it for a day it will come back on.

 

Your rad may be clogged, after all it's 25 years old?
Cooling fins could be separating, crap in betwwen fins as well.

 

You most likely have air in the system somewhere. If the car still has the OEM Radiator, there is a phillips head bleeder screw right where the top rad would attach. You need to slightly open this valve when filling the system or the car will overheat. If this doesn't solve the problem, you could have a failed water jacket O-ring.

-Sheldon.

 

How I always done it is use a old 20 oz coke bottle put it in the radiator top, fill it with a little water or coolant, then start the engine, it should get the air out of the system, or it could be a bad radiator like said before. It might just be old, clogged, or messed up inside. They are pretty cheap to get, and will last a good while.