Have my truck on jackstands, 98 auto. 24v, when I spin the brake drum in nuetral I have noise coming from my differential, can touch fluid in there with pinky. Is it normal to hear a noise from there, (sort of a low rumble). Few months ago I drove through a deep puddle and didnt think much about it. If diff. is bad is it best to buy a rebuilt one or something, I think repairing it is beyond my ability. Have noticed more noise going down the road for sure, thought it was bad tire wear. Thanks, Byron.

 

Try listening through a stethascope touching the rear in different places to pinpoint the noise. Sounds like a bearing going bad.

 

I agree with the above post, but I would also pull the differential cover and catch the oil in a drain pan. Then filter the oil through a chunk of white cloth and look for metal.

One other thing to test is to remove the driveline, and roll over the differential without the driveline connected. The rear universal joint will make a grinding noise many times when it is failing. If that is it, it is what is known as a cheap fix!

For the most part if a bearing is failing, it is by far the best and most economical solution to have a reputable differential shop rebuild the existing unit using first rate aftermarket parts from a specialty differential parts supplier. Avoid OEM replacement parts, they are too expensive and for the most part rejects.

Also, check to be sure it is not a small rock in the brake drum, that can refer noise along the axle tube.

 

thanks for suggestions. Tried my wifes stethoscope and could only hear it on the pumpkin, not anywhere along axle shaft. As long as i turn the drum counter clockwise the drive shaft isnt turning so I guess that rules that out.Will try draining fluid and looking for metal and a differential shop local. Will keep posted and thanks again. Any idea what kind of cost I might be looking at? Byron

 

I'd say cost would depend on what failed, and whether or not the ring and pinion are damaged or OK.

If it is a low rumble, my guess would be carrier bearing?

 

If you are just spinning one axle by hand, the noise you are hearing is just the spider gears within the differential, and is normal. The best way to listen is to be turning the driveshaft so the differential is being powered the way it is while driving. The most effective method is to have the engine running in gear, while all drive wheels are raised off the ground, and a helper in the driver's seat to keep the speed within the range where the noise occurs, while you are underneath with a stethoscope. I don't recommend this without a hoist however, for obvious safety reasons.

 

Taken me a long time to get back here ,I finally drained the rear end and strained it through a white cloth, I couldnt find a speck of metal, all the gears and teeth looked fine. I am only spinning the one axle so I think it might just be the spider gears torquefan was mentioning. IF i only have drive to one wheel than I dont need friction modifier do I? THanks all.

 

no no modifier needed on open rears