I put chassis ears on my diffs and recorded the sounds. https://youtu.be/7SwCCLD3FSc

Trying to find the source of the mild grinding groaning from 30-50 mph.

 

Has the sound been there quite awhile? If the noise comes and goes depending on whether or not you're applying the gas, then that might sound like my front differential did before I replaced it - although this sounds much worse....

 

Yeah the groaning has been there since I bought it at 145k. Front diff definitely had water in it as the fluid came out milky a few times before it cleared up.

This is the first time i've put the ears on it though, so idk what to compare it to.

 

Highly likely it's either the pinion bearing or one or both axle sideplate bearings.

1. Water in oil obviously NOT good
2. The epoxy paint coating on the inside of the differential case can also deteriorate and add to the lubricant failure.

I replaced mine by finding a good used one at a wrecking yard. Make sure you get the right ratio dif. Be sure to replace all the seals while at it!

 

Thanks for the reply.

What is the best way to diagnose bearing problems? And how did you know the wrecking yard one was good?