I *think* I am having some rear diff problems. I have a diff that has leaked for the last 15,000 miles over the past 4 years. I don't drive much. Anyway, I have been trying to kill the leak. Started with a new pinion seal, no dice, still leaked. Then a new pinion flange - Still leaking. I can also see fluid coming out the driver side of the 3rd member. So, I know I need to pull it and RTV that seal. I recall freeing up the breather at one point, so I am afraid that it forced oil out through that seal for some time before I knew anything about it.

Also, When I replaced the flange, I reused the pinion nut and torque'd to spec which was several turns more than what it was on there at to begin with. When I did this, I had the rear of the truck up on jack stands. I tried to turn the wheels and at a regular interval it would bind, just a little bit. It would rotate on around, but it would definitely bind up at the same point everytime. So I backed off the nut a turn or two and it seemed to rotate freely. I left it there and have put maybe 2k miles on it since then.

Truck has 166k on it and I have 31's on it now, though I want to go bigger, but not radically. Has to be streetable.

I am looking for recommendations - Should I get a junkyard diff and then pull mine to see if it is busted? Or just pull mine and have new qears put in it, if they are indeed busted? Thing is... if I regear the back, i gotta do the front too... and that means more money...

also, a junkyard about 2 hours away has 4.56 diffs, front and rear, from a v6. Is it okay to swap that into my 4 cylinder?

Thanks all!

what do you want to run for tires? If 33's, i'd say the 4.56's would be fine if your on a budget. Better than 4.10s thats for sure. I'd pick up the v6 diffs. that way even if u decide to regear youv'e got the stronger v6 diff to set-up.

I had 32X12.50's Mickey Thompson Baja Belted on there back in 1998 when Mom was paying rent... now I'm paying rent and no way am I spending that kind of coin of something that soft again. Young and dumb, I guess. Yes, I've been driving this truck since 1996

All that to say that I can run that size without rubbing <img src="/forums/images/graemlins/zombie.gif" alt="" />

I want to run 33's or 32's. If I run 33's I'll put either bj spacers from 4crawler on there or a bodylift. I'd love a total chaos, but the money thing again.... And I have 31's on there now (BFG A/T KO) that have 90% or better tread that I would have to sell.. but yes, someday I will have some 32's or 33's on there again.

so no problems bolting in a v6 third into a 4 cyl truck? Is it an upgrade even?

no problem at all
http://home.4x4wire.com/erik/diffs/

I've got 2 junkyard 4.88 V6 diffs in my '85 4Banger. Slips in and bolts up just fine.

Why not just have the seals and bearings replaced and leave the gears alone? I very seriously doubt your r/p's are broken or messed up. Sounds like seal issue most likely...

Remember, seals keep oil in, so if oil / fluid is getting past the seals to the outside, most likely a seal. You don't seem to indicate any other problems or symptoms that would lead one to believe the r/p's are messed up....

Thanks,

James

My concerns that the R&P have been damaged are as follows:
lots of noise coming from the back beyond 65 mph. From Richmond to NoVA, which I drive once per week, you do 80 mph or get out of the way. At this speed, the truck has a lot of vibration and noise. If I grab the TCase shifter, I get a lot of "feedback" and movement, which seems to be at roughly the same beat that the pinion would be spinning.
Also,
When I tightned my pinion nut to spec, there was binding in the axle when the tires were rotated with the axle on jackstands. I had to back it off a round or two. This makes me think something is up.

I would prefer a pull and replace scenario and save my dough for other things... What bearings do you think I need to inspect and wouldn't I have oil out past the drums if the bearings went bad?

I don't really know what all's involved in pulling a 3rd, I guess...

The carrier bearings could be going bad. I had noise from my diff on my 98 Chevy 1/2 ton, and it was a carrier bearing going bad. I got noise at highway speed just driving and under acceleration. The guy that did my diff on that told me that ring and pinions rarely go bad. Usually it is a bearing that eats it.

One way to test if it is the ring and pinion is when you let off the accelerator, does the noise get worse (deeper growl)? If so, this is the ring gear pulling the pinion to it and letting you know there is a problem with the gears.

When you accelerate, the ring gear pushes the pinion away, and noise there is usually a bearing (pinion bearing) going bad.

When my carrier bearings were replaced, the gears looked great and guesses indicated that I had about 3,000 miles left on that carrier bearing before it was going to let go.

For testing/checking wheel bearings, drive the truck down the road and swerve (turn steering wheel) from side to side. This loads the bearing and if that bearing is going bad, it will make noise. If you swerve left, you are loading the left wheel bearing, and swerving right loads the right wheel bearing.

Remember, you have carrier bearings (for the diff) and also a set of wheel bearings out past that. IF the seals on the diff are going bad, you can get them leaking...Also, there may be two sets of seals per side (a seal at the diff and one at the wheel) on these trucks, I just don't remember, sorry....

Another thought is that you need to inspect / change your u-joints. Not for the fluid leak, but the noise and feedback.

Hope some of this helps....
James

Let us know what you find....

Yes, when I let off the gas there is a serious growl... I heard it last night driving around the neighborhood at like 20 mph. Left off gas... deep growl...

Turning side to side only made me look drunk. No noises or anything were produced.

U joint was replaced last year but I will give her a good check...

I think I am going to try to get spousal approval for a new diff. I am forced to drive a heep with serious drivability issues until then. Would you believe the truck is way more comfortable on the highway than my heep? <img src="/forums/images/graemlins/lol.gif" alt="" /> I never thought I would say that about my truck

little update-
Was trying to confirm if I had a bad 3rd without pulling it - Dropped the drivershaft and spun the passenger side and held my hand on the pinion flange, could feel the diff pulsating through the flange. Knew that couldn't be good, so I pulled the tires and drums off. Following the Haynes, I drained the diff fluid, which I had just replaced not long ago. It came out looking like chocolate milk??? The drain plug had about an inch of shavings on it. When I spun on the driver side wheel, the passenger side would spin. But not vice versa.

Off to the store to get a flare wrench to take the brake line off. I think I am going to put 4.56 gears back in. gotta pick them up tomorrow. Overall, this has been easier than I thought it would be. But then again, I'm not done yet <img src="/forums/images/graemlins/scared.gif" alt="" />