I know the AST caps can go bad, but what about the Radiator cap? Also, is it possible for a Pettit AST cap to go bad in about 7-8 months ? Just trying to figure out why my damn coolant level stays 3/4" from the top instead of 1/4" from the top. I took a 3 hr. road trip after filling my radiator and it still ends up 3/4" from top. How long does it usually take to effectively burp the system??? Whatever amt. I add to bring the level to 1/4" from the top it blows it out the overflow tank. Why ??

 

i think if it goes down to 3/4 tank and no lower, it should be fine. maybe try a higher pressure 16psi cap? i think its fine as long as it stays consistent after spitting in the overflow.