At 09:28 AM 1/15/03 +0000, William Davies wrote:
>The presence of the rubber valve doesn't necessarily mean it works!
The presence of a working anti-drainback valve doesn't necessarily mean
that the oil won't drain back anyway! My filters have always lost most of their
oil after a couple of days, and when I check the anti-drainback valves
before installing and after replacing the filter, they are always working
perfectly.
I believe that the oil "drains forward": not back through the pump, but through
the main oil galleries and out via the main bearings. Look at the engine,
and you will see that the main bearings are lower than the filter.
I guess the only way to know for sure would be to remove the oil pan
right after running the engine, and watch to see where the oil drips from. :-)
On other types of engines (e.g. my Subaru), the oil filter is very low on the
engine,
with the top of the filter screwing into the bottom surface of the block,
and this sort of draining could not happen.
Doug Braun
'72 Spit
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