Expert: keith - 7/27/2005

Question
I have a 1991 Chevy Cavalier, 3.1L that I just rebuilt the lower part of the engine. The car was run hot and cracked one of the heads and was replaced. Due to the oil and water mixing the bearings on the crank were washed. I machined the crank,replaced all main & rod bearings with a matched set, new oil pump,new water pump,new timing chain and gears and all related gaskets. Some things I replaced simply because I was right there and the vehicle has 177,000 miles. Now when I start the car and let it warm up, the oil pressure drops slowly as the engine temp. rises to normal operating temps. Can camshaft bearings being worn do this? Can valve lifters do this? That is all that is really left and I'm stuck. Will you please give me some advice. Thank You.

Answer
Hi Rodney, if the crank bearings were washed then the cam bearings were washed also. The least little bit of wear on the cam bearings will cause a significant loss of oil pressure. It is not likely that the valve lifters are the cause because they are made of steel and coolant don't effect them the same as it effects the bearings, they would have to be worn really bad to cause that much of a drop in the oil pressure.I hope this helps you, If you need more info just let me know. Regards, Keith.