Diff tear down - burnt oil? *picture heavy*

[Nomad]

Not sure if you are following my Warn Pinz thread but I have the rearmost axle out of my 712. I got the axle in my shop and started to tear it down.



Once we got the cone or cover off the witches hat this is what we found.



The smell of burnt gear oil is very strong and inside the cone is this.



So what is this? What would cause this? Where might the problem be? Here are more pictures if that helps you help me!



The burnt oil is all over the witches hat but wipes off with a bit of effort.



This is pretty chunky but doesn't appear to be metal shavings, just crud. I guess I will drag a magnet over it today just to make sure.



There is some slop between the locker sleeve and gear, not major but more than I would expect.





So what am I dealing with here? There is nothing obvious yet but I can and likely will go deeper into the diff. Also there is a fair amount of oil in the intermediate tube between the two rear axles. Is this normal?

Cheers and thanks in advance for any suggestions or ideas.

[Jim LaGuardia]

E-brake dust and mud mixed with gear oil, oil is from seal or locker sleeve o ring.
Fairly common.
Excess heat from a sticky e brake would explain the burn smell.

[Stekay]

Lotta work considering only two bottles and one can on the workbench.

[Nomad]

Thanks Jim...I spoke to a buddy of mine too, who worked in a diff shop for 3yrs. He said not to worry to much about the burnt oil. Makes sense about the e-brake, mine has certainly been a problem in the past.

I have the witches hat torn down more. I am thinking about replacing the bearing, seal, o-ring and related parts. I have read a bunch about the brass pilot style bushing, http://www.pinzgauer.com/showdetails.ph ... o=9006500/ and it being a problem. Should I replace this while I am in here? Is it more of a problem for the t-case and front diff? Very curious.

The slop in the locker clutch or selector sleeve is all lateral. None in the mesh of the gear surfaces. So I think it is fine. I could easily take a video of the slop to verify.

Cheers

[Nomad]

Here is a link to some pictures of this bushing I am talking about....

http://home.comcast.net/~hillmanpinz/EX-II.html

cheers

[undysworld]

The article you cited refers to the front internal driveshaft vibration damaging the bushing at the front of the transfer case. That driveshaft has nothing to do with the bushing at the rear of the truck.

However, what does the bushing cost v. how much work is it to get to the thing? It's probably so cheap that you could replace the thing "just in case", if you've got any concerns at all with the condition. Better safe than sorry, in most cases, at least in my opinion.

[Nomad]

The article you cited refers to the front internal driveshaft vibration damaging the bushing at the front of the transfer case. That driveshaft has nothing to do with the bushing at the rear of the truck.

Ya I am aware. But this bushing is in the rear too is it not? It is in all witches hats on the trucks, correct? I take it (assuming) it is not so much of an issue in the rear of a Pinz 712 as it is in the front.

However, what does the bushing cost v. how much work is it to get to the thing? It's probably so cheap that you could replace the thing "just in case", if you've got any concerns at all with the condition. Better safe than sorry, in most cases, at least in my opinion.

The bushing costs $10, I bought one, for the exact reason you state. I am in here now so might as well do it all up.

I attempted to modify one of my pullers to do the gears in the portal box. Decided to stop with that as it is an expensive puller. So bought the right puller for the job instead. I am rebuilding the portal boxes while I am doing the rear axle. The witches hat is also getting new seal, bearing, o-rings and springs on the locker. I have some questionable brake springs so also doing that. Last bit I bought was diff vent kits for both rear axles.

It is nice having the axle out of the truck, easy to work on anytime of day. It has been raining a lot here too which makes working on things outside sucky. Everything is cleaning up nicely. I will take some pictures during the process.

Cheers

[undysworld]

Ya I am aware. But this bushing is in the rear too is it not? It is in all witches hats on the trucks, correct? I take it (assuming) it is not so much of an issue in the rear of a Pinz 712 as it is in the front.

Probably not an issue at all in the rear of any Pinz, at least not due to driveshaft vibration, IMHO.

Yes, they appear to be the same. However, according to the article you cited, the damage is caused from vibration of the internal drive shaft. The rear diff. lock, whether on a 710 or either rear axle of a 712 would not be receiving this vibration, or if it did, it would have to travel through the T-Case. Only the front diff lock and the 4x4 lock, because of their locations, would be effected. The rear diff lock of a 710 would see no additional vibration beyond that seen by either rear axle of a 712, I'd think.

However, the 710s would be more likely to have the driveshaft vibration than a 712, due to the increased length of a 710's driveshaft.

[Nomad]

Makes sense....

I bought the bushing, again only $10. I may install it or I may not. Depends on how hard it is to get the old one out and if it shows any signs of wear. Being a soft metal it seems to me like it is a wear item. Just like a pilot bushing in a clutch. If it wears, it also seems like it should be replaced about as often as seals and bearings.

All food for thought!

Cheers

[Jim LaGuardia]

Bushing is only used at transfer case locker front output shaft, the other shafts are direct spline mounted (no pilot).

[Nomad]

Bushing is only used at transfer case locker front output shaft, the other shafts are direct spline mounted (no pilot).

You are definitely the Pinz guru Jim!

I couldn't tell if it had the pilot bushing from the parts book. I was under the impression it was there. Once I broke down the witches hat though it was very obviously not there.



Cheers