nagging problem

[89white50]

Well, after changing to 180 thermo, new rad cap, and cutting off the heater core (just connected the two rear hoses) coolant is still pushed out of the overflow after about 150 miles. Pressure just keeps building, and will eventually puked it out. To quickfix it i pull over and let a ****ton of steam out and as soon as the pocket of air is gone the motor sucks all the coolant back in the temp is great...

I was thinking maybe a headgasket has a small pinhole in it, besides that i am out of ideas.

oh my rad only has about 10k on it too...

 

[blkcobra50]

Well, after changing to 180 thermo, new rad cap, and cutting off the heater core (just connected the two rear hoses) coolant is still pushed out of the overflow after about 150 miles. Pressure just keeps building, and will eventually puked it out. To quickfix it i pull over and let a ****ton of steam out and as soon as the pocket of air is gone the motor sucks all the coolant back in the temp is great...

I was thinking maybe a headgasket has a small pinhole in it, besides that i am out of ideas.

oh my rad only has about 10k on it too...

Did the thermostat that you put in have a small hole somewhere on the flat mounting surface around the spring?

 

[Strype]

My old 86 did that and I never did figure it out

 

[89white50]

lol guys cmon. And i cant remember, i bought a stainless steel one from Steeda. ill be taking it out beginning of next week though.


LOL strype....

 

[5.0Droptop]

sounds like a head gasket failure. You can get the strips to test if it had exhaust gasses in the coolant.

 

[rd]

The long shot is that you have air in the cooling system somewhere. I had a minor amount of this in the 79 recently, and a quick 20 mile drive at 60+ burped it out, and its been ok since with a 190 tstat, all summer.

Mine eats coolant over the course of a couple months, so when its low, it will overflow when I shut it off. Then I fill it up again. Been like this for 25 years.

However, my best guess is that you have a head gasket going away.

 

[89white50]

man i just did them about 20k ago. I over heated it real bad when the first set went, probably warped a head. guess it will just have to do till i can finish building my 331 this winter/next spring.