How Much Oil Do you Use?
Derek Pulvino
dbpulvino at hotmail.com
Wed Jan 28 15:58:08 EST 2004
Bernie,
Finally getting back around to this and it seems pretty logical. Just
wondering, is "blow-by" a symptom of bad rings only (or maybe more
accurately a phenomenom originating in the block), or can sufficient
pressure move past the valve guides and seals and then work through the oil
return galleys...resulting in an air/oil mixture through the breather
system.
So I guess the short question is, can blow-by come from the head as well as
the block, or only the block.
> >
> > But still didn't answer the question, why is this happening. What are
> > potential culprits? How can I be sure it's the head, and not turbo
>seals,
> > or a problem with the crankcase vent system? I figure leak down will
>tell
> > me block vs. head, but how could I tell about the turbo seals or if the
> > cranckcase vent system is my culprit?
>There are no common, contact type, elestrometeric rotary shaft seals, just
>labyrinth seals across which there is positive gas pressure to the return
>oil passages. Bearing wear causes seal clearance wear with resultant oil
>blow by. If the turbo to IC and the IC to IM hoses are heavily oil wetted
>you have either a piston blowby problem coming thru the crankcase breather
>system to the turbo fresh air input (the compressor wheel should be oil
>coated), or the turbo bearings are shot, (the compressor wheel not oil
>coated).
>
>Do a compression check, first dry and second with oil injected into the
>cylinder to better seal any ring leakage. If no dif, you have a valve
>problem. Incresesd comp points to a ring problem.
>
>Tis good to isolate the source of your problem, such that it is easier
>monitored, but DFI if IAB!
Not sure this is absolutley black and white. Varying degrees of "broke,"
consumption, and tradeoffs therein.
Derek P
>
>Bernie
>
>
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