Posted by Keith in Washington on Wednesday, March 15, 2006 at 2:00PM :
In Reply to: Engine Blowing Oil posted by David Bizzell on Tuesday, March 14, 2006 at 9:05PM :
Often that is caused buy a stuck PCV valve, which some of these old trucks have, and worn compression rings, which gives you lot of blow by. The PVC is usually located on the pipe that runs from the intake manifold to the block just below the manifold near the rear of the engine. Worn or broken rings along with worn cylinders cause blow by which goes directly into the crankcase. Some blow by is always there and that is what the PCV valve is there for. It sucks it out and sends it to intake manifold to be burned. If the PCV is restricted or blocked pressure can build up in the crankcase. The pressure has to go someplace. It often escapes through the dipstick or the oil filler cap. It litterally can almost pump oil out the dipstick. I have seen it happen on my father in law's car. Funny thing is the dealer put a hose and clamp on the dipstick tube and then routed it to the filler cap where they welded a short pipe. That sucker built up crankcase pressure until it blew the hose off the dipstick tube and covered everything with oil and left a major puddle on the ground.
Check the PCV valve and make sure that it is flowing. It should be a simple metal tube/pipe with a check ball in it. It can be cleaned with carb cleaner. They often are very dirty with sludge and carbon build up. Make sure that the tube is clean and that the fittings and the intake manifold hole, where the fittings screw in, is open and unrestricted. Then clean the dipstic tube and check for oil again. If there is still lots of oil coming out it may be time for a engine rebuild.