Update. The machine shop says all guides are within spec, no cracks either. I am having them install positive exhaust valve seals just in case.
I just took another look at the exhaust manifold from the passenger side. Only the #8 manifold port shows signs of oil traveling out of the
exhaust port and down into the exhaust pipe. Oil there is black from carbon and sticky. The other ports show only dry carbon.
The #8 cylinder exhaust port which happened to have the valve closed the last time I shut it off had oil laying on the back side of the valve.
Had it not been closed that oil would have run down into the chamber. The only source I can think of for oil on the back side of the valve
would be guides if there are no cracks? Oil lays deepest inside the valve cover at the rear and deep enough to reach the valve guide. Is it
possible the even if guide is in spec that oil would make it's way down the guide to the back side of the valve IF submerged in oil and
only using umbrella seals instead of positive seals?
I have seen other posts about oil in number 8 exhaust port on various forums so it does happen, but usually guides were bad.
Any ideas about a source for this oil would be appreciated. The only other thing I can think of would be valve cover gasket
leak at rear running down and somehow getting between the manifold gasket, but no sign of such a leak.
Thanks!
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