Hi. I have a 95 Park Ave with 114,000 miles and it is losing a significant amount of coolant, sometimes as much as 1/2 gallon in several days. Visibly there aren't any external leaks. There is some foamy green gunk on the oil cap but the oil level is OK and the oil doesn't look milky. The exhaust is white when the engine is started, but it is cold and humid outside and it seems to be OK after the engine is warmed up. I occasionally get a faint smell of coolant inside the car.
I just did a pressure test with the engine cold and the system isn't holding pressure. It drops a few psi within about 30 seconds and continues to drop slowly after that (even after tweaking the pressure intitially to allow for hose or other system expansion). I checked for external leaks at the hose attachements but didn't see any seepage. I started the engine with the tester attached and the pressure reached the "test mark" on the pressure guage before the engine reached operating temperature. (I shut the engine off at that point because the test gauge moved past the "test mark" into the "danger" area).
I replaced the intake manifold gasket, water pump, upper and lower radiator hoses, and thermostat one year ago at 100,000 miles after the water pump failed.
I would appreciate any ideas or suggestion on what the problem might be and possible solutions.
Thanks
Rick