Rear pinion seal leaking

[Mile Marker 42]

I've asked this before, but looking for clarity. 2003 Monaco knight rear pinion seal leaking. Anyone replace this and what did you do about bearing preload when tightening nut back up? Some say count turns of nut coming off. I spoke to a highly rated but far away shop and they say don't do it that way, that measuring preload is a must. I don't trust shops to work on my coach. Thx in advance.

[jacwjames]

I am not an expert, don't claim to be but I have some heavy equipment experience, large mining equipment, I was actually maintenance manager for a large mining complex. I was pretty hands on. But I know my limitations.

Having a seal start to leak may be an indication of a deeper problem, bearing failure etc.

I've watched good mechanics tear down and reassemble ring and pinion carriers. Not an easy process, definitely takes a skill set to get the teeth to mesh correctly, set the backlash, bearing preload etc. Normally they'll use feeler gauges to get the mesh close and then use a type of white paint to check the mating surface and dial depth gauge to check backlash. A good mechanic can get it very close with only minor adjustments to finish. I could take multiple attempts.

That said I don't think I'd tackle the job myself. I'd consider possibly pulling it myself and inspecting for any problems as far as wear or damage to the teeth, bearing problems/play etc. Would probably find a local shop or individual who could set it up. If I were going to do it I'd just go ahead and replace all the bearings.



But if you decide just to try and replace the seal here is a parts breakdown document that I had in my files, there should be a tack on the chuck/axle to confirm what you have. I'd try and find a maintenance manual on this and see if they have a procedure for doing this with the carrier still in place. You'll need a large accurate torque wrench, you could consider try to figure out how many FT/LBS it takes to tighten the nut a little more and then how much to break it loose and use the average. The seal itself is cheap, probably less the $25.



I'll throw this out there, you might try a seal conditioner to see if that stops a leak, I used this on the front axle of my axle of my tractor and it worked. https://www.amazon.com/ATP-AT-205-Re.../dp/B000NVW1LM


I would suggest draining the oil, check for any signs of metal, adding new oil and the Re-Seal and monitor.

[Wild Card]

Don't do it yourself. Bearing preload is critical. You may have to remove pinion and replace a crush ring and torque to an ungodly ft # that your just not gonna get.

I would have to contact the mfg for specs.

I had a Ram3500 dually that the pinion seal was leaking, warranty. Dealer replaced seal, rear end roared badly. Took back and said look if it was just as easy as swapping the seal Ida done it at home. You gotta pull the guts and go through the set up. Ram actually swapped my rear. Dealer would have never got it right.

[Mile Marker 42]

Originally Posted by jacwjames

I am not an expert, don't claim to be but I have some heavy equipment experience, large mining equipment, I was actually maintenance manager for a large mining complex. I was pretty hands on. But I know my limitations.

Having a seal start to leak may be an indication of a deeper problem, bearing failure etc.

I've watched good mechanics tear down and reassemble ring and pinion carriers. Not an easy process, definitely takes a skill set to get the teeth to mesh correctly, set the backlash, bearing preload etc. Normally they'll use feeler gauges to get the mesh close and then use a type of white paint to check the mating surface and dial depth gauge to check backlash. A good mechanic can get it very close with only minor adjustments to finish. I could take multiple attempts.

That said I don't think I'd tackle the job myself. I'd consider possibly pulling it myself and inspecting for any problems as far as wear or damage to the teeth, bearing problems/play etc. Would probably find a local shop or individual who could set it up. If I were going to do it I'd just go ahead and replace all the bearings.



But if you decide just to try and replace the seal here is a parts breakdown document that I had in my files, there should be a tack on the chuck/axle to confirm what you have. I'd try and find a maintenance manual on this and see if they have a procedure for doing this with the carrier still in place. You'll need a large accurate torque wrench, you could consider try to figure out how many FT/LBS it takes to tighten the nut a little more and then how much to break it loose and use the average. The seal itself is cheap, probably less the $25.



I'll throw this out there, you might try a seal conditioner to see if that stops a leak, I used this on the front axle of my axle of my tractor and it worked. https://www.amazon.com/ATP-AT-205-Re.../dp/B000NVW1LM


I would suggest draining the oil, check for any signs of metal, adding new oil and the Re-Seal and monitor.

Thanks Jim. I changed the fluid 2 months ago and went with a thicker weight hoping it might help. No metal shavings or anything came out. It is just a leaky seal. I have used Bars Leak many times years ago when I was a auto mechanic and a customer wanted a cheap fix for either a radiator or water pump leak, so I am open to a seal conditioner/stopper. Our old tow car was a Saturn Vue with the Honda V6 motor. When I bought it (used), it had a water pump leak and I didn't want to tear it down and replace the pump and timing belt. I added Bars Leak, and after a few months, it stopped leaking. I'll browse the attachment you sent. Someone on another site said I may have shims that handle the preload opposed to crush washers? If that is the case, with shims, you can tighten it up all you want. Thanks for the suggestion.

[vito.a]

First you need to figure out what rear axle is in it. Then look up the pinon bearing preload procedures for the axle.
Like you said, some are crushable sleeves, but they are usually only used in light duty. Most of the heavy Dana and Eaton rear axles use shims to set bearing preload. In that case the pinion preload shim stack and pinion depth were determined upon initial assembly. This will be a simple remove and replace with just applying the proper torque to the pinion nut.

It would be nice to get the rear axle off the ground so you can turn the pinion by hand to feel for any grinding or drag both before and after.

[Mile Marker 42]

To follow up on this, I have a Dana S150 rear end and the bearing preload is set up with shims from Dana. If I am only changing outer pinion seal, then no need to worry about bearing preload. Thanks to those that commented

[Rob_M]

Vito is correct in that a lot of the large differential pinion bearing pre-loads are set with shim stacks and once shimmed correctly the nut is just torqued to a set spec.
Simply changing the seal on one pf those diffs would only require proper re-torque (it will be substantial) and replacing the lock-nut with a new one.

Because there is so much else the pinion has to turn, feeling the difference before and after changing the seal will be impossible. That pre-load is usually measured in inch pounds, in an empty housing turning only the pinion.

Find a breakdown and rebuild manual of the diff and verify if the preload is set with shims or crush sleeve.

Side note, in most differentials every time the pinion nut is removed, a new one is supposed to be used as it is a lock nut and if it backs off it trashes the ring and pinion.

[Rob_M]

Originally Posted by Mile Marker 42

To follow up on this, I have a Dana S150 rear end and the bearing preload is set up with shims from Dana. If I am only changing outer pinion seal, then no need to worry about bearing preload. Thanks to those that commented

I was writing my above response before seeing yours.
Be sure and get a new pinion nut. You should be able to change the seal yourself. Good luck.

[Mile Marker 42]

Originally Posted by Rob_M

I was writing my above response before seeing yours.
Be sure and get a new pinion nut. You should be able to change the seal yourself. Good luck.

Nut and seal ordered, and yes it is shim type. Normally, I would do this, but I found a rear axle builder who can do it on a Saturday morning and he can knock it out in 3/4 of the time it would take me. A few hundred dollars to have him do it is worth it to me. Thank you.