Re: [AMC-list] AMCRC event, and...

[tom jennings <tomj@xxxxxxx>]

On Wed, Jun 30, 2010 at 6:03 AM,  <wrambler242@xxxxxxxxxxx> wrote:

> I'd suspect a problem in the pump, not the modification. Perhaps the blueprint is too tight? While it would pump oil like a muthas. It may have failed to allow enough lube to the ends and gear shafts etc,

(At work now, crazy morning.) It's nothing to do with my external
cooling mod, at least directly. More on that in a minute.

60 psi at hot idle means that at IDLE! the oil pressure bypass valve
is OPEN. That means either (1) things that eventually dump pressure
(mains, rods, cam, top end, etc) are clogged/restricted or (2) the
pump puts out more volume than the system can handle.

I can't rule out clogs; there's no way to tell short of a full
disassembly, THAT is not gonna happen! So for diagnostic purposes, I
have to set it aside (with one eye on it...). If I get rod knock or
something down the road, oh well.


I did get the pump exquisitely built. I will have to remove it for all
diagnostic paths. First thing is, the cover will come off (easy) and
from that alone, I can tell what happened -- if I can turn the gears,
sheared woodruff key. If the cover is gouged to crap, mechanical
interference. I will do at least that this coming weekend. The cover
will come off in 15 minutes, three bolts, there's plenty of room for
that.

Assuming no metal-to-metal, and a sheared key, it is simply oil back
pressure that stressed the gear drive. It did take 1600+ miles to
shear it; and it did happen as I was revving 3000 rpm in 2nd getting
up to speed for the highway. That strongly implies it was hydraulic
load, as opposed to something like a chunk of metal got in it,
whatever.

I think there is a partial chance I simply over-built the pump. The
filter+hose setup flows really well on it's own; you could basically
breathe through it. More than a few GPM, and with the new teflon
lines, that's not what's loading up the pump.

If it *IS* just hydraulic load, I might make a key from something
stronger than soft iron, and find a new relief spring and/or shim the
plug to lessen pressure, and see if I can hold operating pressure to
50psi. If it is high volume all the time, 50 psi is PLENTY of oil for
this ancient engine.

And I hope I didn't score bearings. I did turn it off within a second
or two, with clutch disengaged. I pulled over, inspected everything
for leaks, checked the oil level, then I did start it for one more
second as a double-check. It hasn't been turned over since. Operating
temperature was spot-on 185F in the center of the cylinder head. I'm
not *too* worried about this.


My guess is, I have two "problems" neither of which by itself would be a killer:
  1) too much oil volume (crazy problem to have, I know :-)
  2) oil pressure relief spring problems, causing high pressure

I should not have left it to run at 80psi this whole time. Together
they could stress the pump.

Or, I'll yank it and find some completely other problem!
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