Meritor Differential failure - 83000 miles

[azSkier]

2006 Essex, K2 chassis, Meritor differential fails at 83,000 miles.

One of the pinion bearings failed. The resulting play damaged all parts in contact with the pinon bearing and gears. Freightliner is trying to find a compatible bus differential (new or rebuilt) to install.

There is no rust and no sign of any high heat. I don't know what caused this failure. I am pretty sure that by the time I realized there was a problem, significant damage had been done.

Here are some pictures where I am trying to show the play in the bearings.
The tech explained to me the pinion teeth have significant wear and are very rounded.

[BFlinn181]

I'd never expect rust in a diff, the interior is bathed in gear lube splashing around as it spins. Do you know the history of the differential? Was lube changed at proper intervals, proper level checked in between changes?

[twinboat]

Bound up or worn drive shaft slip joint, bad U joints or improper ride height can all cause drive line vibrations. That vibration can cause all sorts of problems.

[azSkier]

I have a lot of records from the prior owner, but nothing related to differential or hub oil changes. I have assumed the oil was original when I had the hub and differential oil changed when I purchased the coach. 2 yrs ago. I also had the pinion seal replaced as well. There was no sign of rust at that time and no metal in the oil.

I bring up rust as this is a key reason for the annual recommendation for differential oil change. The oil is good for 200000+ miles, but the fear is water will condense inside and rust the parts.

The ride height was correct when I purchased the coach; was fine last year and is fine now. The u-joints were naturally the first suspect when this problem became apparent. 2 techs have stated the u-joints are fine. I believe them to be original. I will make sure they are changed out as a part of this repair.

Now, reflecting upon things that have happened... I did change out the pinion seal in the summer of 2015. Last March, I had a single drop of oil on the ground and upon review, was told the pinion seal was bad again. I was upset that I had to change 2 pinion seals in 2 years. The vibration must have been happening during my fall 2016 travels. The coach was in storage from November to March.

[mackwrench]

Have the Technician make sure the drive shaft is in "phase" meaning the input and output​ yokes are in line. I've seen where a tow truck driver pulls driveshaft, and reinstall out of time, it can cause a driveline vibration.

The pictures you have here don't appear to show any rust issue, how ever the bearing play is for sure a vibration.

Have tech look at all rear suspension mounting bushings, with enough wear the rear axle can tilt pinion up, causing a severe drive line angle, and pinion bearing failure.

The back to back pinion seal failure is a red flag for driveline vibration.