A couple of months ago I got one of those radiator caps with the lever to vent pressure off. It is an 18 psi cap. A couple of times recently when I get home, I hear gurgling and the radiator expansion tank will start overflowing. Not all the time, did it once a few weeks ago and again today. Temp gauge never shows an overheating condition, car is running fine. You think those caps are no good? Should I just get a regular radiator cap instead? Last, is 18 PSI the correct pressure cap for the LT1? FYI, last time it did it, I checked the level in the radiator the next day and it was fine, so whatever it boiled out, it sucked back in the refill the radiator, it just overflowed the expansion tank when it was bubbling out.

 

try bleeding it and see if theres some air in there

 

I'm going to do that, but this is just all the sudden. Have not had it open since last spring when I put the optispark/water pump in.

 

ok so old cap did not fail. could have a bad cap. not unusual to happen. i tried a aftermarket cap and it lasted 6 months. replaced with oem and has been fine

 

I will do that today. Checked the level this am. Radiator level is fine, expansion tank is about half full. Maybe the expansion tank was too full. But that still does not explain the cap blowing off.

 

mine did that when my cap went bad. Had people telling me my head gasket was blown lol. I looked at the cap and could see cracks in the rubber so i replaced it and the car never did it again.

 

isn't the LT1 cooling system 16#?

 

Everything I see says 18#. Just got a new one today. We'll see.

 

i might be wrong its been a while since i have my Z28 and i didnt have it that long.

 

better bleed her to make sure theres no air in it