Re: Packard TSB 56T-20 - Low Oil Pressure

Posted by PackardV8 On 2009/10/28 22:03:23

quote:
"causing air bubbles in the oil flow in the block and the heads (especially the left bank)shouldn't that make main bearings #2 and #4 more prone to failure since they receive .."

I kind of doubt it. As long as oil pressure is showing on the gauge then OIL is delivered. Perhaps along with some air yes but not enuf air to do damage. If there was enuf air to do damage than the oil pressure gauge would show very near ZERO psi or maybe only 3 or 4 pounds.

Let me put it another way:
The oil pump is an oil pump not an air compressor. oil does not compress. Only the air in the oil will compress. So some reasonably large amount of oil must exist in order for the gauge to read ANYTHING. Of course if the gauge reads ZERO then air is all there is in the system but that becomes a moot point.

I've driven PLymouth Chev and AMC 6 cyl engines albeit low speeds of say 25 to 35 mph around town for many miles while the gauge would drop to nearly zero at idle and i had to keep the engine speed up just to keep a little oil pressure. Those engines continued to run 25K miles that i know of and more after if fixed them.

I'm not sure what causes the main bearing premature wear yet. I'm guessing poor bearing insert material, oil gallerys too small or poorly drilled at the factory or maybe crankshaft flexing.

Most likely i suspect main bearing material inferiority first. But the oil gallery diameter and machining is the easiest and first to addreess. Crankshaft rigidity would be the most difficult to determine if everything else checks out ok.