I just bought a 91 GT/auto and a week after I bought it the temp outside hit the 90s, and at that point the car started to run hot. (between the "O" and "R"). I have replaced the thermostat (from a 195 to a 185), the fan clutch, the fan (because mine was cracked and a little melted), and now installed a three row radiator. Just got done with the radiator and drove it and after about two miles with the a/c on it's back up at the "O" and "R". I noticed that there wasn't any pressure in the upper radiator house when I got back, and up till today when I put in the radiator it always did make pressure.

The car is just starting to agrivate me because I've been working on it more than I hav ebeen driving it. Is there anything I might have missed? It has a new water pump on it from the previous owner.

Thanks for any help.

 

Well sounds like the thermostat isn't opening since there was no pressure on the upper hose.Maybe you got a faulty one,replace it with a different one and see what happens.

 

-The thermo don't have to open to make pressure.
-How did you bleed the cooling system? you may have air in it?
-did you replace the cap with a new one?
-Alos open the cap when it's running to see if their are bubbles in the rad, if thier is that's bad=head gasket.
-the water pump could be going south. Although it's not common somethimes waterpumps will break impellers and therefore it partly losses the ability to move coolant.
-Hook up a mechanical gauge to give you an accurate mesurement of temp.

 

well that seems to be normal for that car. thats the stock temp range

 

The car was building really good pressure until I installed the 3 row radiator yesterday. No bubbles in the radiator so I guess thats one good thing.

 

you probably have air bubbles in the cooling system take the cap off when it cold and start the car and squeeze the upper radiator hose and it should ake the air bubbles out you will have to fill the radiator up more bc when the air bubbles are taken out it will lower the coolant level also you have a half and half coolant mixture of fluid and water right

 

50/50 correct.

 

I think I might have it fixed. I pulled out the 185 and replaced it with a 160. Took it out and stayed on the "A". Turned on the a/c and it ran between the "A" and "M", it hit the "M" once at a stop light and then went right back down when I pulled away. It was only 80deg outside right now, so I am crossing my fingers that it will still run cool tomorrow when it's back into the upper 90s.

Thanks to everyone for their help

 

I don't want to burst your bubble but if you have nbo mods a 160 thermo seams a bit overkill for your car. If the car is designed to run properly with 195 thermo and it doesn't, putting a 160 in it it just hiding the problem. Plus a 160 proly won't let the car go into closed loop. Now on the other hand if the car is heavily modded I can see why you need a 160 thermo.

 

160 is to much