legal-z

i posted earlier this week on a possible o-ring failure in my car, but i wasn't getting any indication of burning coolant. no smell, no smoke, no overheating, however, my coolant level warning was going off every couple/few days. after closer inspection this weekend, it appears that there might be oil in my coolant. i can see it floating around when i take off the cap. even after a week of filling it with coolant every couple of days, there is still no smoke and the car idles fine and doesn't get hot. i have been unable to find any obivous leaks and i have examined the end caps of the radiator to the best of my ability without actually removing the radiator. anyone w/any ideas?
thanks in advance for the suggestions.
andy

911GT2

I don't know what that indicates, but I can tell you oil in the coolant is NEVER good. And usually indicates rebuild time.

David Beale

As long as you just have a light "oil slick" I would say the oil issue is normal. Is your overflow tank filled to the top? One cause of what you describe is a vacuum leak (believe it or not). Here is what happened to me - when the car warms up the coolant expands, and some is forced into the overflow tank. When you shut it down, it cools off, and the coolant shrinks, creating a vacuum, and this draws coolant back from the overflow tank. If either coolant cap (filler - no spring, or pressure - spring - on the AST) has a slight vacuum leak the car will not draw the coolant back, and if you keep adding coolant to the engine, eventually it will overfill the overflow tank. It will leak out where the overflow tank filler neck is inserted into the overflow tank. The small hoses that go between the overflow tank and the engine can also collapse under vacuum and will also stop the draw back.

The solution is simple. Two new caps, and to be sure, I also replaced the poor quality small hoses with proper coolant system pressure hoses (there is no pressure in that part of the system but pressure hoses will not collapse). If you replace the hoses, you may have to re-route them as they are not as flexible - I found it not too hard to find a good route for them.