99 malibu coolant leak

There are no visible signs of a leak however i keep adding anti freze. The intake gasked, radiator, hoses, thermostatg housing, and coolant bottle are not leaking. Im not getting a funky film on my windshield so i do not thing that it is the heater core. It does not seem to be leaking untill the car sits for a while after driving. The coolant bottle was replaced last year. Is there a design problem with the pressure cap? Im bewildered by this. Please help.:screwy:

Let it run to operating temperature and then let it sit in the driveway. Shut it down and pop the hood. Over the next few minutes check all around the radiator/fluid connections and engine with a flashlight. It sounds like a real small leak. Good luck

It is your head gasket on the look on the top of your engine and you will probably see what looks like a wet residue on the seem where the head gasket sits. that was the problem when i was leaking coolant on my 2000 malibu. hope it can help u out.

There are no visible signs of a leak however i keep adding anti freze. The intake gasked, radiator, hoses, thermostatg housing, and coolant bottle are not leaking. Im not getting a funky film on my windshield so i do not thing that it is the heater core. It does not seem to be leaking untill the car sits for a while after driving. The coolant bottle was replaced last year. Is there a design problem with the pressure cap? Im bewildered by this. Please help.:screwy:

have you found out if its the head gasket? I'm being told i have the same problem....my mechanic says no way to check w/o opening up the engine....its gonna cost me, too......let me know what you find.

ya i am positive that is what it is...The mechanic took apart the engine to see what was wrong. and that is what was wrong. Since I had that gasket replaced it held up for about 2 years and now it is slowly starting to leak again. So my advice to you learning from my own mistake is make sure you put a quality gasket on there so it doesnt happen again.