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On 03 Dec 2003 03:39:16 GMT, (LaBomba182) wrote:

Subject: Fuel transfer/polishing pump
From:

On 29 Nov 2003 20:48:01 GMT, (LaBomba182) wrote:

Subject: Fuel transfer/polishing pump
From: (Steven Shelikoff)

Not much difference between diesel and oil.

Perhaps, but there is a world of difference between the tolerances of a
fuel
injector pump and an oil pump.

True. But that's a red herring since it's not usually the oil pump that
wears out due to dirty lubricating oil.

Not quite. A 350 Chevy engine will run for a long time, years maybe, with dirty
oil.
A diesel injection pump and/or injectors with dirty fuel will not.

Yeah, but after that Chevy 350 engine runs for years with dirty oil,
you'll probably find that the bearing surfaces are more prematurely worn
than the oil pump. The reason is that the bearing surfaces are speced
to operate with clean, filtered lubricating oil. After years of
running, the filter has probably clogged so much that it's always in
bypass mode, and maybe even torn, allowing all the dirt to wear the
bearings. The oil pump, on the other hand (and unlike a fuel injector
pump) is designed to run in dirty oil... so it's tolerances have to be
less. All dirt trapped in the lubricating oil filter has already passed
through the oil pump.

And *that* is why your statement above is a red herring, because the
lubricating pump always pumps pre-filtered oil so it matters very little
what the filter is doing.

By the way, instead of saying "But that's a red herring since it's not
usually the oil pump that wears out due to dirty lubricating oil." I
should have said "But that's a red herring since it's not usually the
oil pump that wears out *prematurely" due to dirty lubricating oil."

Steve