Packard Forum Index » Post-War (1946-54)

1948 Custom Eight : I have a funny knock. It started while out touring and I just pulled over and had AAA bring it to a garage. They say transmission but I think it is a clutch. If you start the car in neutral it's there. If you rev the engine it the knock gets faster with the motor. Put the clutch in an it goes away. Clutch? I was about to tear apart the drive shaft to see if it was the transmission, or rear end but any advice would be a lot faster. Thanks

I doubt that it's your tranny. Sounds more like a pressure plate finger hitting the throw out bearing or the lever...does the clutch still feel the same as it did before the noise started or do you feel a pulsation through the clutch pedal when applying foot pressure?

I would say no difference in the clutch pressure and when I drove it today I don't recall a pulsating in the pedal

There is a possibility that the thrust bearing has worn to the point that the crankshaft is moving forward or backward excessively and allowing the flywheel or clutch assembly to hit somewhere on the back of the engine or inside the bell housing. I would pretty much rule out the tranny and the rearend and start by raising the car up evenly front and rear with a lift or by using a jack and jack stands and place the tranny in neutral. then remove the inspection cover that bolts to the lower bell housing and using the correctly sized socket and ratchet, start slowly turning the crankshaft and see if it makes any noise or comes in contact with something when you turn it by hand. If you can't duplicate the problem that way then fire it up and see if you can get it to do it by running it in neutral. If it does then try to locate the cause using a length of hose as a stethoscope.

Dam I don't want to hear that ! If I'm figuring this right that could mean a tota engine l rebuild right?

It's all speculation at this point and anyones guess as to what it may be. Thrust bearing failure alone is highly uncommon and seldom occurs. It's hard for anyone to diagnose a noise without actually hearing it but since you stated that it goes away when you depress the clutch then all anyone can do is offer suggestions based on the symptoms. All you can do is start the process of elimination and report back with your findings.

First things first. Disengage the overdrive and see if the noise changes.

Then buy a stethoisscope from NAPA and locate the likely area.