[DeTomaso] Oil Smoke From Breathers

[JDeRyke at aol.com]

In a message dated 5/18/11 4:05:46 AM, dfcex at pacbell.net writes:

> If I still have this issue, how does one test for valve guide or valve 
> stem seals (with the engine together)?
> 
Dan, once in a while, someone will put a PCV valve in a rocker cover 
upside-down (they fit either way), and high rpms will fill the cover with enough 
oil to allow a mis-installed PCV to suck PINTS of oil into the intake by 
vacuum and blow it out the tailpipe! The fix is to install the valve correctly.
But smoke from a tailpipe usually means oil got into the combustion 
chamber, and there are only two paths: past the rings, or past the seals, guides 
and valves. Oil or heavy deposits of carbon on a sparkplug will confirm oil in 
the combustion chamber. A leak-down test will confirm or eliminate the 
rings as the leaky source, leaving only the guides. But there really is no 
external test for bad seals. Someone's gotta go into the suspect set of valves, 
pull the retainers & maybe the springs and examine the seals and guides. And 
once you do that, its very little more trouble to replace them. I like 
Perfect Circle all-teflon seals, but there are others. Sometimes, pulling the 
intake and exhaust manifolds will allow examination of the ports behind the 
valves; carbon build-up there almost always means leaking seals. With race 
cars, ENGINES are regarded as consumable assemblies!
As to what else may be causing it, worn guides are a fact of life for 
performance engines but poor valvetrain geometery will make guides wear faster by 
putting more side-thrust on valve stems. Very high rpms will also do it. 
Then the worn guides take out their seals and you get smoke. Good luck- J 
Deryke