Questions and Answers

GMC Sierra Oil Leak? Q. 1990 GMC Sierra. I have developed a small pressure oil leak and my oil pressure is about 70 at times higher. Does this mean my oil pump might be going out ? Runs great no smoke. I use Mobil synthetic oil. Has almost 300,000 miles. I have never replaced anything on it except filters. Mary

A. This is not very clear. It's leaking? Where? Oil pressure sounds high for that mileage but I would love to see that kind of pressure! The sending unit could be out of whack and sending a false signal to the gauge. A leak may be caused by a bad gasket or a clogged PCV valve.

If the PCV rattles, start engine and make sure there is vacuum to it. If no vacuum, the port under the throttle body is clogged and needs to be opened up. A clogged PCV will cause oil to be forced out of the engine at every weak point, rear main seal, front main seal and valve covers.