Chevrolet Repair: motor problem, oily residue, pcv valve

Question
Hi Barry i just bought a truck and i'm getting alot of blow bye coming out the valve covers but not much out the tail pipe would you know what would cause this? It's a 94 chevy box van 7.4 liter eng. It has 78000 miles no knocks sounds good just lot of smoke coming out the valve covers. Thx Curt

Answer
Any "blow-by" is caused by failing or failed rings, and, as for the tailpipe smoke, or the lack of, the catalytic converter may be burning it off before it reaches the end. Check inside of tailpipe for oily residue. I would guess your check was with pulling the PCV valve out of grommet, and visable smoke is "puffing" out?! Have you checked for a failed V.C. gasket that may be leaking on the exhaust manifold(s), which would appear as though it may be coming from the valve covers. Good Luck