I have a 2000 Dakota, 4X4, V6, 5 speed, and open differential. Yesterday it started making a noise and vibration from the rear upon deceleration, and I didn't have to touch the brakes. I was about five miles of highway driving from home when it started so I turned around and went home. Every time I let off the gas it got worse to the point I thought something was going to break when I got to my driveway. Everything feels and sounds fine when accelerating, and I backed it up hill about 100 yards into my garage without any issues that I could hear or feel. I just jacked it up, pulled the wheels off. The brake drums came off easy so I don't think I have a hung up shoe and no parts fell out on the floor. My next guess is U-joints, but don't want to pull the drive shaft unless I have to. Is there something I have overlooked that it could be? I know I need new rear tires, those were on next weekends to do list, but since it happened suddenly and got worse and worse in a five mile drive, I doubt that is it.

Any help and ideas are greatly appreciated.

Thank you, Nate

 

Make sure the drive shaft bolts haven't come loose. Check the gear oil in the diff while there.

 

grab driveshaft with both hands and try to twist it while watching your u-joints...shouldn't have any slop. If it does could be U-joints are shot. If U-joints are good my next guess is your differential might be taking a dump. Pull the rear diff cover and check fluid for metal and check your gears. You can also check your pinion bearing for slop by shaking the driveshaft back and forth and watching the yolk on front of differential for movement.

jack both rear tires off the ground and place on jack stands and spin tires and see if you here any noise. Grab the tire at 3 and 9 0clock position and try to force tire in and away from truck to see if there is bearing slop. Can also spin the tires to see if you hear any noise...

 

I may have found the culprit. I put it up on stands and among other things, pulled the plug off the differential cover. It's really low on oil, maybe out, and it's my fault for not checking it. I put the 1-1/4 quarts of 75W90 that I had on hand in it and I still can't feel it with my finger. I'm going to get more and fill it and go for a short drive. The damage may have been done though. I did shake the rear tires, there is a little slop in them, but not an unusual amount. No noise spinning the tires by hand or using the engine to turn them while on the stands. I couldn't find any slop in the u-joints either. The only perceptible movement in the driveshaft seems to be coming from the transfer case.

 

Let's hope you caught it in time. Fill it up and take for a drive get up to speed and completely let of the gas without hitting brakes and see if you hear a howl or growl coming from the rear end. If you do the gears are damaged.

 

On positive note if you don't live in the rust belt these differentials really aren't bad to change. I've done much more difficult ones

 

Hope for the best, but prepare for the worst (it ain't that bad though). It probably didn't happen suddenly, so the wear most likely occurred over an extended period of time, degrading till you finally felt/heard it. The gear oil also travels through the axle and lubes the axle bearings, so an entire rear end replacement might be in your future.

You can run it while on jack stands to see exactly where the noise is coming from.

 

Thanks guys. I filled it with oil, it took about two quarts total. I only got about 20 feet out of the garage and knew it wasn't fixed, in fact the noise is more noticeable now, or maybe I am listening closer. I backed into the garage and could hear it, when I don't think I could hear anything in reverse before I put oil in it.
I put it back up on the stands again and spun and shook the tires by hand, no noise or excessive play in either wheel. I started the engine, put it in gear and let it go, got out and walked around the rear. No noise that I could hear. The rr tire was spinning, the lr wasn't. I kicked the lr, got a clunk and it started spinning. (both were spinning last night), but there was still no noises.. Do you think replacing all the bearings in it will solve the problem, or are new gears involved to. What I have found for this as far as a differential rebuild kit is all new bearings and races, I have also found a new ring and pinion. Can't find anything for the carrier, I did find a 9.25 carrier, but mine is a 8.25. And where is the best place to get the parts? I do live smack dab in the middle of the rust belt and this thing is bad, bad, bad with rust. Once again, the rust is totally my fault since I have owned the truck since it was new.

 

Running it dry would damage everything that needs lubricating and that's not just what's in the pumpkin. Personally, I would get a diff from a junkyard...maybe a front hit, or buy one already pulled with a warranty and throw that in.

 

I gotta agree with this sentiment. Rebuilding a rear is not a simple undertaking, need precision measuring equipment, and you MUST be EXTREMELY picky on tolerances and settings, otherwise, you end up with a rear that is noisey, at best, or blows itself up in short order, at worst.

Pick up a replacement, clean it up, change the fluid, etc, and just swap it in. That will end up being a LOT less expensive than a rebuild.