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No oil pressure - rebuilt engine

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Subject: No oil pressure - rebuilt engine
From: "John Speiser" <>
Date: Sun, 27 Aug 2006 10:53:24 -0400
Before starting up an engine that has not been run in months, I usually prime
the oil distribution system.  Detach the feeder hose going from the right rear
block to the oil gauge, and pump oil into the block at about 40-50 lbs
pressure (from an old propane tank, rigged for this purpose), until oil flows
from the holes in the rocker arms.  The assumption is that if oil can get up
to the rockers, it has already flowed to lubricate the bearings.
Just tried this on a rebuilt 1965 MGB engine, but found no oil flowing from
the rocker arms.  I pumped in about 2 quarts.  The pumped-in oil filled the
oil filter (the hanging spin-on type, using a Moss adaptor), and some ended up
in the sump, but none came to the oil hoses leading to & from the oil cooler.
I don't know if it is reaching the crankshaft bearings; my guess is its not.
Reconnected the oil pressure gauge hose and cranked from the started motor
with the plugs out, but got no reading on the gauge; not even a flicker.  Took
out the pressure relief cap and spring and cranked again.  The new oil pump
put out enough pressure to push the "bullet" relief valve out of the block, so
I assume the oil pump is sufficiently primed and working.  But why isn't it
pushing oil through the gallery that leads from the oil pressure relief valve,
upwards across the back of the block to the outlet (where the hose to the oil
cooler is connected)?
The block was cleaned and prepared by a reputable shop, well-experienced with
MG engines, so I assume they properly replaced all the gallery plugs in the
right places.
The rear rocker arm pedestal (and only that pedestal) contains an oil gallery
that delivers lubrication to the hollow rocker arm shaft, which delivers oil
to the rocker arms.  I'm pretty sure the rebuilder put the correct pedestal at
the rear position.  That pedestal has a little interlocking tab on top, which
the other pedestals lack.  I don't know if the rocker arm shaft can be put in
backwards, thereby - perhaps - preventing oil from entering the hollow shaft.
But even if there is a problem with assembly of the rocker arms, I still don't
know why I'm not getting oil flowing into the hoses to & from the oil cooler.
Ideas welcome!  John in NJ.

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