Packard Forum Index » Pre-War (1899-1942)

My 1936 Packard 120B was sitting in a garage for approx 20 years. After putting new oil, spark plugs, etc., the car started up fine and sounded like a quiet sewing machine. When I drove around few blocks, I started hearing a knocking noise. Its not a constant loud banging noise, but it comes and goes away. When the engine warms up, the sound usually goes away. I cant figure out what it is??
I can hear more from underneath the vehicle, inside oil pan.

I had the same problem with the six in my 38,so I pulled the engine last monday.When I pulled the pan it was pretty clear that the #2 main was failing.I don't think the pan had ever been off and cleaned.It had about 3/4" of crud in the bottom and in the lifter galery.
Try this when the engine is knocking,ground each spark plug(one at a time)and listen to the knock.If the knock doubles it's probably a rod bearing on the cylinder that was grounded.
I also had cam bearings due the same thing,but it had large drop in oil pressure when the engine was warmed up.

Sounds to me like its crying out for a new owner - Me! especially as I have a rebuilt 1936 engine with about 5,000 miles on it (streetrod dropout) that would drop right in....

Thank you for the information. Can it be fixed by just removing the oil pan? or the engine needs to be pulled out?
Thanks, Tony

How much are you asking for the engine?
Thanks,
Tony

You can install new rod and main bearings and rings with the engine in the car.Removing the head and pan.If no damage is found to the journals.
My engine only had 61k miles on it,but all the bearings showed signs of debri passing through them.
This was most likely caused from years of storage,and all the nasty stuff setteling in the pan.
Hope you don't have any major damage.

I hadn't even thought about that engine since I bought it about a year and a half ago. If you are serious, I would be happy to hear what you think it is worth - location is Dallas, TX and I would not sell it, nor would expect you to buy, it without hearing it run, so give me a couple days before you and your pickup truck head this way. David Flack, flackmaster@sbcglobal.net

You should be able to pin point a cause without tearing into the poor thing.

For one rod bearing knocks don't get better as the engine warms up, they get worse.

Don't rule out the fuel pump.

Lets suppose you have a piston problem. If the car doesn't miss then you can hook up a compression tester to each cylinder and start the engine. If you have a low relative reading on one cylinder then look for a broken ring or a stuck ring. Be sure to ground out the plug wire or you will damage the coil.

A damaged piston will also show up as a low first puff during a static compression test.

You could also have loose carbon banging around in there too.

Another likely culprit is a sticking valve. That you can find with a vacuum tester.