Cummins Diesel Forum banner

Rear End HELP

2K views 22 replies 12 participants last post by  Hot Stuff 
#1 · (Edited)
Got 125,000 miles on my rear end fluid which is amsoil SVO heavy weight stuff. 8 quarts, not 4. at 115,000 miles I checked fluid and was still good and see thru and had viscosity still. Well, a couple nights ago, i started to hear clicking at take off. The next day i scoped out where it was coming from and i think it is my rear end. I checked the dip stick and it was all bubbly and thin like water almost. i drained it and it came out black like water. I put new stuff in heavy weight stuff from walmart. LOL, did it at walmart parking lot in 10f weather, most of clicking went away, about 75%,. I notice it mostly under heavy starts and slowing down, and weird noises while turning. but not all the time. IF i let off throttle, i dont hear clicking. Very weird. When I get back to florida, which should be in another 2000 miles or so since im in appleton, wisconsin now, im going to pull the cover and scope out the innerds. There was shavings on dipsitck and drain plug, but thats good, not just floating around in the fluid. I think its normal, especially for all the miles on the fluid and considering my rear end usually has about 10,000 pounds on top of it when its only rated at 9350 I think. Anyways, im thinking my posi is shot.

What do you guys think, if it is my posi, will I screw up my gears or axles or is the damage done??? Is the posi easy to take out???? Its not like I need the posi unit anyways, its hard to do a burn out with 25,000 pounds behind you. lol

Thoughts, hopefully my rear end wont bomb on me on the way home. I already put 1300 miles on it in 2 days.

PS. it was really bad, i was at manheim PA area where I dropped off my trailer and it sounded loud even with no trailer. Then went to walmart to do my thing, and for a few miles it still clicked then went away. But under heavy load now, it happens till, but not like it used to.

Anyways, sorry for the book for a simple question, so, thoughts??? help, anything?? oh, and I did check the joints on the driveshaft, they look fine, haha
 
See less See more
1
#2 ·
WTF, where is all the gurus at??

UPDATE, on way to IL, under throttle it would vibrate, once off throottle, it would be a smooth ride, that was with 3 trucks, now with 4 cars going to florida, under throttle is smooth, but once off throttle, it vibrates, WTF??? confused !!!!!! HELLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLLP
 
#8 ·
Rear end noise.

It's most likely your Ujoints. I had the same problem that got progressively worse. I too thought it was my rear diff - as I had just had the dealer months earlier redo it due to the limited slip going away. Turns out - it was the U-joints.... The symptom fooled the heck out of me and it sounded and felt just like the chatter/shake from a rear diff that has clutches slipping...
 
#3 ·
One of the u joints on the drive shaft on one of my trucks looked fine and didn't wiggle but I took it of and half the needle bearings were powdered. Just saying this because I had the same issues as you with this. I might be wrong but I'm just throwing it out there.
 
#4 ·
I hope you saved a sample of your oil for amsoil to look at. I had a jeep with a badly set up rear end and it would grind for a second when I let off the throttle.
 
#6 ·
When you replace the gear oil at wal mart did you replace the posi lube. Not sure if wal mart sells the posi lube. If not stop at a auto parts store and get the posi lube and put it in. It will chatter without it. Also as Cummins in Kansas said, I've had the same thing with u-joints that seem tight and look good that were bad. Mine was always the u-joint connected to the rearend. When you stop check your hubs to see if they are getting hot. Good Luck
 
#7 · (Edited)
3rd gens trucks with the AAM axles DON'T require "posi" lube. Just general 75W-90 synthetic gear lube.

Also, with these posi's, there is basically NOTHING in them to wear out under "normal" usage. There are NO clutches (which chatter), NO cones and seats. Nothing but a worm gear that spins and builds fluid pressure, causing the 2 axles to spin simultainiously. That's why they work, and don't work the way they do. Most people don't realize that these LS's are actually a very good "street" unit. They were designed to act like a standard open diff under normal driving, be easier on tires, easier on fuel milage, and easier on the truck in general. Granted, most of us don't care for them because we're used to the old skool clutch style, or cone and seat style that WORKED all the time and were very predictable.

Is it easy to remove, yeah, for the most part. BUT, you have to have a differential to put back in, ie. another LS, or a standard open diff., then swap bearings etc. Then set the gear back up (dial indicator and special tools required). I've set up several of these. Fire away.
 
#12 ·
I had the same issue almost and it was my center u-joint.Put 3 new greaseable Spicers in it.Vibration gone.Part number for my 2007 DRW 3500 is 5-188 UT !! Hope this helps!:thumbsup:
 
#14 ·
Thanks.

Oh new symptom now, i will do hwy sppeeds, left off throttle, then once i hit the throttle, you hear a clank.. haha, getting worse,

As for rear end fluid, i just used 85/140 non synthetic with no posi lube. Im gonna open up my rear either way just to scope things out and gonna dump some more amsoil svo in it. 125,000 miles of same diff fluid with severe use like I do is simply amazing. gonna do the spicers also. I think the snow this year that ive been in just killed the grease, let alone the truck now has 135,000 miles. Stuff is bound to start breaking now. Other then that, she is running like a champ, i am starting to lose mpg though. Maybe my filter is dirty and combined with winterblend and howies and deisel kleen, 7-8 mpg aint cutting it, yuck, havent cleaned my filter either in 30,000 miles. I need to hitt the dyno too to make sure my power is still there and change out my 40,000 mile oil and filter, not the bypass, justt gonna dump some delo in it, not amsoil, run it 20k, then do a full amsoil again. Be sure to check out my sample page later. I will post up this weekend if it was the rearend or joints,. Thanks for all the help guys:yourock::yourock:
 
#15 ·
With that new "clank" you describe, it sounds like it may be a pinion bearing. I would definitly check out the U-joints. It's a good possiblity that's all that's wrong. But it's starting to sound like something other than just a joint.
 
#16 ·
if the u-joint is bad and adds slop and vibration to the drivetrain, it will cause premature wear/failure to other components such as the pinion bearing. I would make sure that it isn't something simple like replacing a u-joint or two before making many more trips, could save you a lot more money on repairs and downtime.

Have you ever replaced the u-joints or are these the originals?
 
#20 ·
It sounds like you've got a time bomb on your hands.... I would definitely get this fixed before something actually fails and causes even more damage. I know you've got deliveries to make but some times you just need to stop and take care of what takes care of you. Hopefully it's just the u-joints and you can be back in business quickly.

Just my .02
 
#18 ·
Very typical U-joint symptoms, clanking comes from the loss of needle bearings and whining comes from dried out and or missing needle bearings... Save the rest of your drivetrain and switch over to some quality greasable u-joints.
 
#21 ·
Ditto. Man, I know you're busy and all, but if this thing grenades, I really won't feel that bad because you keep neglecting to get it looked at. You sould have had it looked at the other day when it started. Come on bud, save yourself some hassle and get it looked at NOW. If the rear shaft were to come out a fly across the road, who knows what or WHO might get hurt.
 
#23 ·
You think they're big, You should see the front axle u-joints on the 4wd's!! They're huge.

Glad you got it taken care of too!!!
 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top