[SEL] OT - expansion of metals in oil pumps

[Bill Dickerson]

For the engineers - rob, etc.

Engine oil pump - automotive gear type. Gears are steel (or some sort of
steel product) housing is aluminum - timing chain cover with pump body in
the timing cover.
The gear to housing end clearance is supposed to be VERY close to get the
pump to put out good pressure.
A lot of folks say this is a weak design - that the aluminum will expand
more and open clearances between the gears and the housing.
They claim the fix is to use aluminum gears in the alum housing so they
expand at the same rate, meaning a more accurate and tight pump, longer
life, higher pressure, etc.

Thoughts?

Bill