Rear Diff Fluid Change

[Jake707]

Getting ready to change the fluid in the rear diff. It’s weeping oil both front and back so I’m assuming changing the pinion seal as well would be a good idea.
the LLY has 150k miles on it and I don’t know it’s history more than the better part of the year so it’s cheap insurance.

What fluid is recommended ? Anything I should be looking for when pulling the cover or pinion seal?

SinCe the cover would be off does adding an aftermarket cover make sense? The Banks cover is the new rage but at $400 it’s the most expensive. There’s a BD diesel cover that’s similar in design for almost half the price and then there’s the sea of flat back covers.

 

[2004LB7]

75w90. If you tow a lot in hot weather then 75w140

When you do the pinion seal, Count how many turns to take the pinion nut off so you can put it back with the same pressure on the bearings.

No real need for an aftermarket cover unless you like the bling. It may help Temps a little but. There are numerous threads here on it so you can read up on them and decide if you want one.

When you have the cover off, look for excessive wear and metal particles. Fuze on the plug is normal. Otherwise it is pretty straight forward to do

 

[Bdsankey]

Like said above, 75W90 or 75W140 if you're working the rear end hard constantly. If it's leaking you need to replace the dying seal(s) ASAP before the leak becomes a stream (not saying it'll happen in 2 days but I wouldn't wait months).


I also agree on diff covers, there is not a major gain to an aftermarket diff cover. If I had to buy an aftermarket diff cover it would be the Banks as I personally believe they have the best design and it actually does what they claim (I was a beta tester on my LLY).

 

[KyleC4]

Center punch pinion nut and pinion in-line to each other before removing. Then when going back together tighten pinion nut slightly past being inline with mark on pinion . This will put proper load back on bearings and crush sleeve

 

[ShopSpecialties]

Personally the only diff cover I would run is the AAM one who is also the mfg of the axle. It is like 1/2 the price of the Banks.

Dodge Ram 2003-UP 2500 3500 AAM 11.5 Aluminum Differential Cover Pan Kit GM | eBay

11.5 AAM Aluminum Differential Cover Kit for Dodge and GM Model, 74030017 GM Dodge 11.5 AAM Finned Aluminum Differential Cover Kit, 74030017 Fits 1999-2014 GM 2500 and 3500 series trucks with the AAM 11.5 rear differential. 2003-2014 Dodge Ram 2500 and 3500 series trucks with the AAM 11.5 rear...

www.ebay.com

 

[PureHybrid]

If the pinion seal is leaking, the wear sleeve on the yoke probably has a groove in it too. Most seals from the parts store will not include the sleeve, make sure to get one.

 

[Jake707]

If it’s not just the seal would I need to replace the yoke like in the kit below from the DMAX store? Or is this extra/over kill?
The videos I watched made it important to mark the yoke and put it back the same tightness so how would I do that with new yoke and washer?

 

[Jake707]

Here are some pics I just took showing the leaks.

 

[Jake707]

One more

 

[2004LB7]

Typical leaks, though I haven't seen too many on the plug weld. I really only get concerned when they drip.

 

[Jake707]

I figured they were but for all I know the fluids never been changed so just trying to do it all at one time.

 

[KyleC4]

Ok so if you’re going to replace the yoke there are a few extra steps to take. Remove rear axle shafts from diff. Then take your dial inch pound torque wrench, use adapters and socket to place it on the pinion nut. Then turn it and measure the rotating torque. When you install new yoke, seal, and nut you’ll have to go back and forth between tightening and measuring until you reach your mark. Then add 5 lbs/in. to that. You still want to be over what you measured before replacing. Also get some liquid thread sealer. You’ll need it to lightly coat half the internal splines of the new yoke. And half towards side that faces diff not driveshaft.

 

[ChrisPerry]

Check the vent tube and hose. If they are plugged it will cause a diff to weep like yours is doing.

 

[Ron Nielson]

I would call that a seep, not a leak. Use some brake cleaner, thoroughly clean off all traces of diff fluid currently on the diff, and then watch it for a while. My guess is that you don't really have a problem. When you start seeing drips on the ground, then I'd tackle a repair. And like Chris Perry said, check to see if the vent tube is plugged. Diffs need to breathe a little.

 

[Jake707]

There’s a vent on the diff?
That would call the leak on the pinion side too?

 

[ChrisPerry]

There’s a vent on the diff?
That would call the leak on the pinion side too?

Yes, vent tube comes out of the driver side of the center section, hose attached to it goes up to the frame. If it gets plugged temp will build pressure and cause it to seep from all seals .

 

[Jake707]

Ok pulled the vent tube off. Put a red straw down the nipple on the diff and there was no clog there. I followed the hose and it goes all the way up to the back of the gas filler neck. There’s a black cap of sorts on the end of the hose is that right? It’s clipped to the bracket by the full neck and looks factory but why would a vent have a cap?

 

[2004LB7]

The cap is to keep dirt and debris out of the hose.

Blow into the hose where you pulled it off the diff and see if it is clogged or not

 

[Jake707]

Ok. Makes sense. Must be a vent type cap or something looked like a solid cap but I didn’t pull it down to see. I’ll run my compressed air through it from the diff end up tomorrow and see

 

[2004LB7]

Don't blow too hard. They aren't meant to handle high flow or pressure. Just release a little pressure from heating up or cooling off, etc.