Re: Lubrication System

[jlandry@domain.elided (John A. Landry)]

In Linda Tripp's secret telephone recording, Monica and SLarsonIH@domain.elided were
heard saying...

>So, where does the pressure gauge get its reading at, in the chain?

The oil pressure is taken directly from the main oil gallery on the left side
of the engine.

>During
>summer, the oil pressure drops to zero at idle, especially when wheeling, so I
>up the idle to around 1100 rpm's. I've never heard any of the lifters click or
>any kind of knocking from rod or crank bearings. It's been this way for about
>3 years. (about 75,000 miles)

This is not abnormal... especially if you're using a stock gauge.  As long as
your lifters don't clatter, the general consensus is not to worry too much
about oil pressure.  In you case, I'd consider switching to a heavy weight oil
if you know you're going to be doing a lot of low speed engine operation in
hot temperatures... like maybe 20W-50, etc.

>I've had a couple of Scout owners tell me that cams and or cam bearings tend
>to need to be replaced at about 100,000 miles and is the cause for low or no
>oil pressure. Based on my engine, it seems that the gauge gets its reading
>after the cam bearings. Any thoughts or facts, digesters?

Not true.  It's *possible* to take an oil pressure reading after the camshaft,
but it would be difficult and something you'd have to plan for during an
engine rebuild.  The ports you need to tap are not readily accessible.

I'd agree with those other Scout owner friends of yours that probably the most
likely reason for low oil pressure in an IH engine is *not* the oil pump, but
simple looseness in the camshaft and main bearings.  But I disagree that low
oil pressure automatically means these bearings need replacement.  There's no
shortage of IH owners running engines with mileage well in excess of 300,000
miles with low idle oil pressure and no lifter clatter.

I just rebuilt a 392 with all internal tolerances in the middle or on the
tight side and the hot 10W-30 oil pressure at idle in Drive is only 15 psi.
These engines do just fine on oil pressures that might kill a Chevy or Ford.

Regards,

John L.
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