rear diff

[chappy]

In May I noticed my rear diff was overheating, so much it vented out and the smell is terribleTook it to dealer and they could not find any fault, 2000kms later on holidays, I hear noise from rear diff, took into nearest dealer and founf pinion bearings gone which required new bearings as well as crown and pinion. Replaced all under warranty. I tow 10000 pound 5th wheel, truck's towing capacity is 11000 pounds, 6 litre with 4:10 gears. After 600 mile breakin on new parts, I towed my trailer and used a laser thermometer to read diff temp. It was at 102C or approx 205F. On the way home it was 93C, I am wondering if this will continue to be a problem? Heard from a Guy at Eaton that the first 500 miles of heavy towing will wear a new pattern on the diff causing some heating, but should go away. Anyone out there shed some light on this for me?

[RyanbabZ71]

Did you change the rear diff fluid after you first towed 500 miles?

If not that could be the reason why the rear end went bad and overheated the lube broke down

[chappy]

rear diff does not require a oil change after 500 miles of towing, nothing in manual for this, must have changed it for 2000 and up after they had similar problems like mine, thanks anyway.

[Shaners]

I may be wrong, and I'll dbl check to be sure, but I thought it did tell you somewhere in the manual to change the rear diff fluid after the first 500 miles of towing.  Otherwise I don't think you have to touch it for about 50K miles.

Chappy:  I did a brief check of my manual and I didn't notice anything about changing the rear diff fluid...  hmm...  (I swear I saw it in there somewhere, but maybe I'm remembering my '00)

(Edited by Shaners at 5:34 am on Aug. 27, 2001)

[chappy]

Believe me if the oil was required to be changed and it wasn;t there would of been no warranty on it As it was the dealer thought that it wasn't synthetic oil and I had to set him straight. Still have no real answer why the pinion bearing went bad.Hoping this forum will shed some light on it. Thanks

[NewbieZ71]

Welcome to the forum Chappy, the manual on my 2000 says to change it after 500...Shaners you were right (at least on the 2000 models)....

[Shaners]

Chappy, I looked hard in my 2001 manual and there is no mention in it about changinging the rear lube after the first 500 miles of towing.  The only mention of anything was to run conservatively in order to wear parts in under heavy load situations.  I'd say it would be a safe bet that this situation would create heat do to resistance under load.

The 2000 manual states to change the rear lube after the first 500 miles of towing.

As far as synthetic lube the answer is definatly YES!!!  The manual shows a 'tag" on the rear end that states "synthetic lube".  I don't know why your service mgr wouldn't know this?!?!?!?

I have not heard much about pinion bearings going bad on the newer GM trucks, so I think it would be safe to say you have an isolated case (unfortunate, but isolated).  As long as the dealer replaced the axle and pinion seals when he replaced the bearings and gears, I would think you'd be good to go.

[Kansas Kid]

One thing you might want to look at is an aftermarket rear differential cover.  They increase the fluid capacity and have cooling fins which can't hurt in helping to keep the fluid temps down.

[Pastmaster]

My dad had that problem with his 98 c1500 a couple of times.  In 75k, he wore the seals out twice.  There was no paint on the rear diff after the first year.  Synthetic oil, I've heard, doesn't heat up as bad.

[Shaners]

What year is your truck chappy?

[chappy]

The year of the truck is 1999 3/4 ton Silveralo, 6.0 litre,4:10 ratio