Re: engine guys...Valve seals?

Posted by Owen_Dyneto On 2008/9/15 12:12:26

I agree with Jack that it doesn't have the correct symptoms for a valve seal problem. Why not take a compression test first before you much deeper into it, and let us know the results. Also how about a manifold vacuum test at idle? How much vacuum and how steady is the reading? And how about running a rifle-bore cleaning rod down the oil return holes in the head - very important! These holes are not overly generous is size and if partially restricted you can get quite an accumulation of oil in the head which could then overwhelm the valve/guide clearance.

And one other thing to do first, take the vacuum line from the vacuum pump in the crankcase (joins to the vacuum block near the wiper motor) and remove it and plug the end. I think there's a very good chance that the check valve on the side of the block has failed and you're pulling oil from the crankcase vacuum pump directly into the intake manifold. Happened to me, looked like I was the mosquito exterminator coming down the street.

Comments about lack of lubrication to the valve area doesn't agree with observations on my 56 Caribbean with 90,000 miles. I don't know the entire prior history of the engine, but think it has never been opened. Though the car is a late one (#254) the engine is an early one (C-1137); it doesn't have the valve spring baffles and the valve area is generously oiled when running, enough to spatter all over the inner fender in just a few moments of running.