850 using oil / broken ring?

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Jan 8, 2006
Hi All,

My Mk111 is using a bit of oil and the left side exhaust is getting a thin film of oil inside at the rear of the peashooter. The RH side is fine and both cyls have around 155 psi comp at cranking speed.

To me it looks like a broken oil ring issue in the LHS cyl.

Any other suggestions?
Is there a non-stripdown trick to proving this that anyone is aware of?
Does that compression sound OK when all standard?
Could need new rings, mine burnt oil on the left side before I changed rings last time it needed work (no rebore was required) or it could be the inlet valve guide seal is going on the left side.

Your compression looks good, no other test I know of without a strip down, does blue smoke come out of the left side silencer on rapid acceleration, it did on mine. The blue smoke was the only sign, no performance issues at all.
Valve guide seals are known to pop off now and again. With a bit of care, a good light and a small mirror you can see if it has. It can be replaced without pulling the head

There is non strip down check though I have never tried it.
Disconnect the rocker pipe and blank off the feed. If the smoke stops its the guide or seal if it doesn't it the bore or rings. I would warm the motor up first to ensure the cam gets some lubrication and keep the test as short as possible.
Yes when blipping the throttle when stationary it starts to blow blue smoke on LHS, not so much on the road.

Performance doesn't seem to have suffered at all.

Has anyone else tried the oil line off suggested to check valve guide?
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