Q&A

It sounds like you may have a blown head gasket or cracked cylinder head. Combustion getting in the cooling system can cause an intermittent air pocket, causing the temperature to rise and the heater to blow cold. If I am right how do I collect my cookie! :)

ck vac leak go to inside dash i thank the vac hose u looking for is on driver side heater door is not opening

beginning of head gasket.I had same symptoms.Air in system.So when you rev.it the pump is spinning fast enough to push coolant.Gives you heat.when i was at red light it would blow cold.my temp gauge all over the place.I would bleed system ,add coolant.everything fine.Then coolant level low again more air.I would repeat bleeding process.Eventually the head gasket blew completely.oil in radiator and coolant in oil.Maybe you can just bleed it and add coolant.But if it happens again and no coolant on ground or engine then its going somewhere.

I agree with Jim. you have a head gasket starting to show sugns.

have a shop do a leak down test and a hydrocarbon test to verify.

Roy

same thing for my 2001 saturn sc1 it was a cracked block, since i had just bought the car the dealer just put a new motor in it.

WHAT ABOUT THE HEATER CONTROL VALVE MIGHT BE PARTIALLY OPEN AND NOT FUNCTIONING WHEN YOU REV THE ENGINE IT COULD BE FORCING MORE CIRCULATION THRU THE VALVE AND CAUSING IT TO BE HOT INSTEAD OF COLD AIR ???????????

bottom radiator hose collapsing. sucking together. not letting water circulate. it's making your enginr run hot . when you rev engine it sucks to gether. replace hose. your systems are exactly what happens when a bottom radiator hose collapses.

The problem is lower radiator hose. It is dual walled and the inner wall is collapsing . Revving engine increases pressure pushing past "bubble". Remove lower hose and inspect. Good luck