: 99 Catera head gasket?

11-25-07, 02:59 AM
Purchased her 500 miles ago and almost immediately got a check engine light. Caddie dealer replaced MAP sensor ($440) and I still have the light. Now they want $700 more for two 02 sensors and a throttle position sensor. In the mean time I pulled the filler cap for the oil and found a brown milky mix lining the tube. When I originally checked the vehicle out prior to purchase this brown milky fluid WAS NOT there. Now I am wondering if this brown milky fluid I'm seeing in the tube is from a blown head gasket because water/coolant is in the oil? I am not having over heating issues, but there is a miss in the engine. Would a blown head gasket cause the 02 sensors to go bad or make the check engine light come on? I think I may have purchased some one else's problem child! Thanks for the input. :bonkers:

11-25-07, 03:26 AM
Our engines seem to produce condensation build up (I suspect from the plastic valve covers) this is usually seen as what you described, usually more evident during the winter months. When I first saw that I too was concerned and did an oil change to verify, to my relief there was no water in the oil when I drained it.

11-25-07, 12:36 PM
Head gasket failures, while they can happen, are not common. The cause of the "mayo" is usually as My Opel described. However a more common problem is a leaking oil cooler. The Catera's cooler is located inside the engine block, between the cylinderheads and is immersed in engine coolant. The telltale sign is oil in your coolant overflow tank. Do a search for older oil cooler/head gasket topics to learn more.