I recently had a 1275 engine rebuilt by a reputable machine shop and have
found after about 500 miles of driving that the oil pressure is very low.
It's odd because the crank bearing clearances were checked three times
(once by two guys at the shop and once by me) and the clearances were
found to be middle of factory tolerance. My plastigauge read between
0.0015 and 0.0020 at all five journals. The cam bearings were pressed in
and high spots were removed with fine emory paper. The oil pressure
relief valve was shimmed to proper height, a new oil pump was installed,
and of course a new oil filter was used. After 400 miles I did an oil
and filter change. Oil pressure is nearly 0 psi at 1200 RPM. At 2000
RPM oil pressure is 20 psi and from 3000 RPM the oil pressure hits 40 psi
and increases to a maximum of 60 psi. According to the manual the oil
pressure should be 20 psi at idle (1200 RPM). If I didn't know any
better, I would think it is poor bearing clearance.
Anyone have any other thoughts?
Thanks,
Matt
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