Romano Kroemer wrote:
> Oil circulates in the engine when the oil pump is running. Normally,
> the oil pump is running only when the engine is running as well, i.e.
> 800+ rpm.
The oil pump is hard-geared to the drivetrain and is running at all
times, even when you hand crank an engine.
This is why you can build oil pressure with just the starter, even
at 250rpm or so. (if you are so inclined, I only do this in the
springtime
on first startup)
I think the point that is consistently missed in here is the pressure
on the mains and big ends.
When the engine is not running the pressure is only the compression,
120-170psi times the surface area of the piston.
When the engine is running, the pressure is many times that because
of the power stroke. This puts a lot more strain on the rotating big
ends and mains, which could be argued is bad before oil pressure is
full.
--
Trevor Boicey
Ottawa, Canada
tboicey@brit.ca
http://www.brit.ca/~tboicey/
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