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

Posted by Tim Cole On 2009/11/1 11:32:38

Okay, The original block was replaced by Packard. I don't know how many times. I only know that the present motor number is for a replacement block from Packard. Take my word for the present block. It is no good. The motor blew up.

I think the suggestions as to the length of the oil pump shaft are very good. Perhaps the unit would function better if the shaft was modified into two pieces as were Packard oil pumps in the Eights and Super Eights (scratch that, I checked and the unit is built in two pieces). The V-12 also has oil pump issues and it has a long drive shaft as well.

As for chronic rod bearing problems, well, the air sucking problem will compromise rod bearings because oil foaming is very destructive. On the present block it is curious that the bearing closest to the oil pump was beginning to spin, but if it was getting the most air then that is an explanation.

The original pump did not have the relief valve modification.

I will carefully look at the camshaft endplay because if the cam moves back and forth too much that will cause problems with the oil pump. If the camshaft is already starving for oil that will cause a compounding as well.

The rest of the unit looks pretty generic - current practices using cross bolted main bearings and block stabilizers are far superior which is one reason modern motors last so much longer.

The bypass oil filtration doesn't help either.