[AMC-list] failed 195.6 OHV oil pump....

[tom jennings <tomj@xxxxxxx>]

Got the pump out just now. Wow, is that easy! I was expecting to have
to lift or drop the motor. You have to take out the front lower
suspension mounting bolt to swing the idle arm pivot out of the way,
easy enough.


Bad news. The driven (passive) gear is welded to the cover. Upon
disassembly, the woodruff key is very happy, but the drive gear is
not, now missing several teeth. The gear popped off the cover by hand,
but the cover shows that sputtery abrasive looking metal-to-metal
contact; the oil film failed.

So! Turns out Nash built in .015" total gear end clearance for a
reason! The pump runs at a 45 degree angle, cover down; the driving
gear probably runs the passive gear downward. Nothing retains the
gear, it rests on the cover. How it ever works I don't know. I looked
at the two old, used covers I have, there's slight scoring, totally
normal looking.

I have a good, stock clean pump body, the driving gear is fine, and I
can polish the rough end of the passive gear (and flip it over). Gears
are new, and wear-set is certainly minor.

My dilemma: do I proceed with my modified pump with the stock body for
the huge, sloppy Nash clearance? Or put it back to stock
configuration? I would proceed with my modified pump, except one
thing: the stock covers are cast iron, and mine is steel. I wonder if
when the steel gear lands on the cast iron, it has a different
relationship, friction-wise, than a steel cover? I now know at this
point that many things in this engine indeed rely on such subtleties.

I can only assume the camshaft gear is OK, if it's not, the engine is
a cooked goose.

I can only do this stuff so many times. I'm still gambling of course
that I did no harm to the bearings. I'm running out of "gumption".

I wish it were a 232.

The good news is it's not oil pressure related; almost certainly, the
high oil pressure is caused by the high oil volume from the
close-tolerance pump. Plus or minus the pressure relief spring issue,
which should be dumping at 60psi not 80, but at this point, whatever.
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