Pontiac Grand Am overheating

I have a 1995 Grand Am that is overheating. My mechanic is going out of his mind. So far he has replaced the ECM Module, coolant temp sensor, radiator cap, water neck, thermostat, gasket. The cooling fan is fine. He has done a cooling system pressure check; checked the intake manifold; flushed the radiator. Still the car is overheating. Every day we have to put in a gallon of water and now that it is cold, it is a gallon of antifreeze. HELP!!

A gallon a day with no puddle? Has he checked for a blown headgasket?

The mechanic said it wasn’t the headgasket because there was no white smoke and no smell of antifreeze. There is no smoke, no steam, no high temp light. But when the car is turned off you can hear the “bump bump bump” of a pump and liquid comes out of the overflow tank (not a gallon of it though). Thank you for reading.

Haven’t changed the radiator yet I see. Check it for missing fins, from the back. You might have to pull the shroud back to see it. Change it anyway.

Thank you for your help – I have a date with my mechanic in the morning.

You cannot rule out the possiblity of a failed head gasket. If you have to add 1 gallon of coolant each day and there is no external leak… then where is it going? It has to be going somewhere.

Just because there isn’t a huge cloud of white smoke out the tail pipe doesn’t mean the head gasket is OK. I have replaced many failed head gaskets and many never had white smoke out the tail pipe. They did however have overheating problems and coolant was being lost.

The best way to verify if the head gasket is leaking is to have the mechanic perform a cylinder leak down test. Only then can you be 100% sure the head gasket is not the problem.

It sure sounds to me like he really needs to check that head gasket. While you would expect to see vapor, the lack of it is no sure sign that there is not a bad gasket.

Well, my mechanic has been out sick, so we haven’t run this cylinder test yet, but for four days now the car has not overheated! If it is the head gasket, would it be sporadic like this?