Driveline Noise Problem

[Duckfarmer27]

I have a 30 CCPU that has developed a driveline noise. The truck sat from 1990 or so until last year when I got it running. As it came to me via a nephew from an estate I really don't know the history of any of it. I have removed the gas tank to fix a leak, rebuilt the water pump, rebuilt the distributor, pulled the head because of a leaky head gasket - turned out the head had a crack so another head flattened and installed. Just rebuilt the Marvel carburetor. Probably only a couple hundred miles on it in the past year.

Runs and drives fine. No noise as long as engine has a load on the driveline. Coasting a grinding that to me sounds like either bearing or gear interference starts up and has gotten very loud in a short period of time. Can feel the vibration in both the shift lever and hand brake lever. Noise is the same no matter which gear. Absolutely quiet with a load from the engine on the drive train. Pop it in neutral and no noise. Lube levels OK in both tranny and rear end.

Jacked up the back end. Rotating tires by hand can hear a rumbling noise but hard to isolate - somewhere in rear end.

From researching my available books and on forum I am suspicious it is in the pinion/ring gear. Before tearing into it figured I would run the issue past the experts as I have not found anyone with an issues described exactly like this.

Thanks for any ideas.

Dale

[Bob C]

Drain the oil in the rear axle and see if there is metal in it.

Bob

[Pinesdune]

Not sure on a model A specifically but that sounds exactly like my pickup truck last week, had a bad u-joint , accelerate or under load was fine, let off the gas and rattle and vibrate like crazy


Saving iron from the scrap pile one piece at a time

[Tom Wesenberg]

Pinion bearing nuts may have come loose.

[Duckfarmer27]

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Originally Posted by Bob C

Drain the oil in the rear axle and see if there is metal in it.

Bob

Bob -

You are right - check the obvious first. See attached pictures. Looks like I will have to study up on pulling the rear end. Plenty of metal without working too hard to find it.

Wish is was a bit earlier in the year. My September schedule is insane at this point. Would be nice to be able to tear down and see what is needed prior to Hershey. I've never made it there but my buddy and I were planning on going just to check things out.

Tom -

You might be correct on the cause of this. I can't see a lot through the oil fill hole but there appears to be galling in the ring gear tooth root. I'm assuming if the pinion went out of adjustment that might be one result.

Have to admit I have limited experience tearing into differentials and axles. That will change now!

Thanks to all who responded.

Dale