In a message dated 4/12/06 9:36:46 AM Eastern Daylight Time, davgil@aol.com
writes:
<< However, it seems to me that negative pressure could introduce a reverse
flow into the engine that could allow for the introduction of other
contaminants that would not ordinarily be introduced, and that may not be
burned off
timely. >>
There are some race motor builders that reverse the crank lip seals when
using a vacuum pump to prevent air from entering the crankcase. Slight dust
in
the oil isn't a concern in most cases.
A road going motor never really pulls a vacuum in the crankcase, air just
circulates through the crankcase. There is far more moisture generated by a
cold
engine that there is in normal air.
I did have a customer with a Blazer that was getting severe amounts of
moisture in the oil. The motor checked fine for coolant leaks, turned out they
were
parking in a very damp garage, as in moss on the walls,running water. After
moving to another parking spot the moisture problem was gone.
Harold
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