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

Posted by Jed Sheehan On 2009/10/28 18:46:05

OK guys, for what it's worth, here's my story. My 374 engine was rebuilt in 2005. It had about 93K miles on it and it had been rebuilt at least once before I bought it. When I have no idea. When I got it back from the shop (after we had moved four states away) it was running absolutely great! No lifter noise, no problems at all.

I drove it around town, on the interstate, trying not to be too hard on it but not babying it either. At about 1200 miles, as I was driving at about 55 mph, I started hearing valve train noise. I looked at the oil pressure gauge and it was at zero and the noise was getting louder very quickly. I pulled into a parking lot and turned her off and had her towed to an engine shop.

They dropped the oil pan and found the pump drive shaft had sheared off at the spline. This was a rebuilt pump that had been installed when I had it re-built. The shop didn't remember which of the two sources they use had supplied the pump so I won't speculate here.

The local shop rebuilt the engine and we got a rebuilt oil pump from Bob Aller. The shop noticed that it didn't fit right. It seems the drive shaft didn't line up correctly with the pump shaft and it was binding. We speculate that this caused the earlier pump shaft to shear. They machined the pump to fit and installed the pump. We found the pump was pumping air mixed with the oil (checked at the oil filter supply line). The engine had horrendous lifter noise. It sounded like it wanted to blow something out the top end. I sent it back to Bob who returned it saying there was nothing wrong with it.

That's when I contacted Craig about the Olds pump. The shop had to do some machining on the adapter to make it fit so we think there was a problem with the mount point in my engine. The Olds pump has been in the engine for two touring seasons now, has about 3500 miles on it, and I haven't heard any lifter noise, not once.

Well, that's my story. Maybe it wasn't the pump's fault that the shaft sheared. All I know is that it's running great now.