I have a 2001 Dodge Ram. 1500, 4x4, quad cab, with 109,500 miles on it. I bought it from a used car dealership last saturday. Test drove it with no problems and no noises, drove it all weekend with no problems. Well Monday on the way home from work i started to notice a noise in which to be coming from the rearend. When i got home i jacked up the rear and had my wife get in and start the truck up to let the tires spin free and the noise is deffently coming from the rearend. The noise is kinda hard to explain but it not a grinding noise. It ONLY happens on deacceleration or slowing down. It dose not make the noise when im on the gas. It kinda sounds like the ring and pinon are just really "loose". And it is full on oil.

Any ideas?

Thanks,

 

Make sure it's not the ujoints. Other than that, you'll need to take the cover off and inspect the interior.

 

a roaring noise that changes pitch between acceleration and deceleration is likely the pinion bearing. grab the yoke at the front of the diff (rear end of drive shaft) and rotate it, and wiggle it sideways. you might be able to fee a little bit of looseness, but with all the other stuff attached (axles, drive shaft), you may not be able to feel it.

your 'wheels up in the air' test is valid and the only choices are the center diff (ring, pinion, pinion bearing, carrier bearing) or the outside (rear wheel bearings).

its most likely the pinion bearing with the varying pitch.

 

Yes it has new u-joints in the rear. When i pull the cover how can i tell if the pinoin bearing is bad? And what other things should i look for(besides metal shavings lol)?

Thanks,

 

Broken parts.

Grab ahold of the driveshaft where it bolts to the pinion yoke. Have the truck jacked up, and in neutral, and give the shaft a shake. ANY movement other than rotation is bad. If it moves, time for new bearings.

 

Ok, got an update. I dont know if this is a weird coincidence or if my truck is causing this problem.

I took the truck back to the dealer and they said they would fix it or put another used rearend in the truck. So they took the cover off and found part of some teeth chipped off and the clutch pack was shot. Not to for sure about the pinion bearing though. So they bought another used rearend from a well know auto salvage yard that came with a 90 day warrenty. They installed the rearend and test drove it. Everything great. So i go down there to pick the truck up and i test drive it. It drove very smooth and quiet!!! So i tell em thanks and head for home when i dont even get a mile from the dealership and BAM the rearend breaks down again!

I was turing slight left on an on ramp to the hwy going about 45 when I hear a bang noise from the rear, immediately the truck is making the same noise and symptons as before. I know the dealership didnt rig the old rearend cause i inspected it myself sitting on the garge floor the day i picked it up. So could it be a coincidence i got two junk rearends?? I just dont understand how the second rearend held up to two test drive before it failed.

The truck is back at the dealership and i havent been able to see what the damage is to the second rearend. The truck has brand new u joints in the rear and the tranny was rebuilt 5,000 miles ago.
Thanks,