I previously posted that my 1960 c10, 235 engine, smokes from the tailpipe...blue smoke. I was advised by several on this forum that it should be driven for the rings to seat.
A local machine shop had rebuilt the engine for the previous owner but it had never been started at the time I purchased it. I talked to the machine shop owner about the engine before buying the truck. The block had been bored .030 oversized with new pistons and bearings. New valve guides and hardened seats were installed in the head.
I have recently got the truck inspected and have been driving it some. Compression is app 145 to 150 psi each cylinder as measured with a cheap gage. The truck runs great. It has good power and will accelerate smoothly from idle in 3rd gear.
The smoke seems to indicate a problem with the oil rings. All six plugs appeared oily before driving it on the highway, but seemed to clear up a good bit after driving it about 10 miles at freeway speed. It still smokes.
I pulled the plugs and distributed a can of Sea Foam engine treatment equally through the sparkplug holes, and let it set for three days.The Sea Foam eventually trickled down into the crankcase. I have driven it a total of about 50 miles. The last trip, I drove it up a long steep hill under hard acceleration. I then turned around and let it experience hard engine braking coming down the hill at 70 MPH. It still blows a puff of blue smoke under deceleration.
I suspected valve stem seals but this engine has only O-rings on the valve stems immediately under the valve keepers. My understanding is that these are only to prevent drain down of oil accumulated on the valve cap when the engine is not running. After sitting overnight, the valve cap cavities remain full of oil.It still smokes.
Both the carburetor and fuel pump are rebuilts. There is no use of engine vacuum external to the engine. For this engine, I can identify no common point from which oil could be syphoned into all six cylinders.
Although I doubt it is possible, I can't completely discount a defective fuel pump could perhaps syphon oil from the crankcase into the fuel stream.
I conclude either the oil rings on all six cylinders have a problem but no problem with compression rings,or oil is entering the cylinders through the valve guides.
I hope some you guys with a lot of engine experience will read carefully what I have documented, and offer me your views. I don't believe the smoke is going to go away with time and I suspect I'm faced with tearing down the engine.
meansam
