Todd Mullins wrote:
> Can you think of any possible scenario whereby combustion
> chamber activity could draw a vacuum on the crankcase?
Well, the oil pump is constantly sucking volume out of the
sump for one thing. The oil finds it's way back, but not
right away, especially oil pumped up to the rockers.
From my experience, most modern engines run with a slight
crankcase vacuum at all times. This is of course with PCV
valves, but a PCV valve will only keep the pressure
"no higher" than the air. From whatever mechanism, it tends
to be a bit lower than the outside, a slight vacuum.
You can notice this on engines that weep. The slight
vacuum will keep the oil inside the engine as long
as it is running.
I wish I had more technical reasoning, this is all
observations, and a wild stab with the oil pump.
--
.---------------------------------------Ottawa-Canada-GOSENSGO-----.
/ Trevor Boicey 1992 Celica GT 1975 MG Midget /
`----- tboicey@brit.ca ------------------------------------------'
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