On Mon, 8 Sep 1997 21:38:11 +0000 "Scott Gardner" <gardner@lwcomm.com>
writes:
>Well, I'm picking up the 'B' from the shop tomorrow, after total
>rebuild (everything new except rods/pistons, and the crank was
>turned). Prior to the main bearings giving up the ghost, I had
>noticed my oil pressure was pretty lousy (12 psi idle, 45-50 at
>highway speeds for the first hour, dropping thereafter.) I had the
>Vicky Brit high-volume oil pump put in, as well as the uprated
>relief valve spring, so I should be in good shape. I'm trying to
>figure out what caused the low pressure to begin with. The rocker
>shaft was in good shape, but the cam was badly worn, at least on the
>lobes. The valve guides were worn, but I thought this only
>contributed to oil consumption, not loss of pressure.
> I would like to find out what are the typical causes of a
>gradual
>loss of oil pressure as an engine wears, and which of these are the
>biggest contributors?
>Scott Gardner
>gardner@lwcomm.com
>www.lwcomm.com/~gardner
>
Main Bearings, Main Bearings, Main bearings, followed by big end
bearings, and finally cam bearings.
Most of what you found was the result of loss of lubrication, not the
cause of the lack of pressure. With the exception of the rocker shafts,
all the others are lubricated by splash and/or drip. For example the
guides are lubed by the mist of oil that is present in the rocker covers,
and the cam lobes are oiled by oil running back out of the rocker cover
via the push rod cavities, but primarily by splash from the oil slung off
the main and big end bearings as the crankshaft turns.
Hope this helps
Rick Morrison
72 MGBGT
74 Midget
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