1995 Beretta Overheats with Radiator cap on, But runs at a stable temp when the cap is removed.?

Question

I have a 1995 Chevy Berretta that Overheats very quickly when I have the radiator cap on, but if I remove the cap I can drive anywhere I want for as long as I want. The Engine still runs at a slightly higher temp though. Could this just be a problem with the cap or should I be looking for something worse?

Answer 1

keep looking----what I have found in the past is a leaking head gasket---- combustion gases get mixed with the coolant , after enough air is mixed in the coolant the water pump just cavitates and no coolant is being moved. when you open the cap the combustion gasses are able to vent out and not build up enough to cause a cavitation. Yes, this could also be a loose impeller in the water pump too.

Answer 2

i own a shop,an it needs to have pressure on it so the system can work right ,its not the cap that's causing this,id look for a bad thermostat in it or a hose that's trying to close up when there's pressure on it,,i had a Cadillac that did this a while back,and it had a bad thermostat that was causing it to do it,,you may also want to flush it out real good the bottom part of the radiator might be getting clogged up,it will cause this to happen,good luck with it ,i hope this help,s.

Answer 3

have you changed your water pump? sounds like with the cap on the pressure is to high for the pump to work....also do you have antifreeze in the car? it has a better cooling ability than water and a higher boiling point so make sure you mix properly....also check you hoses to see if one is collapsing when you put the cap on....if your hoses are squishy then they could be bad.....especially if they have never been replaced

Answer 4

Replace cap with recomended 16# cap.

Answer 5

Have the pressure checked but dont be surprized if it is ok. What you are describing is usally something more costly like a head or a head gasket.