Rear axle gets hot - right side leaks oil

[pinzton]

My rear axle is dripping oil. I found oil drips around the rear axle on the right side (rear rear on a 712K) [AND the rear axle] was quite hot (after I drove it 20min total).

See pictures; the left side is dry (except for my oily finger prints); the right side is quite wet.

Any ideas, leads? The oil was replaced ~2 months ago on all axles, and we replaced some boots too.

Thanks, Sacha

[undysworld]

Are you certain the heat was only on the right side?

If you haven't done so yet, you should check the fluid level in that rear differential. I'd suspect you'll find it low, but if somebody overfilled it then you may not find it low. I'd think it has to be coming from the seals where the axle exits the differential, given how much oil is that high on the outside. If so, I'd expect you would also find that wheel drive overfilled. Hopefully, your heat isn't caused by damage occurring in that diff. from lack of lube.

I'd also check to be certain that the e-brake isn't hanging up and causing heat. But frankly, I'm stumped as to why either problem would only heat the right side axle.

Hopefully someone chimes in with better answers.

[pinzton]

You're totally right. It's BOTH sides that get hot; only the right side that drips oil (...editing my post as we speak for clarity)

Thanks for input, will check oil levels, and e-brake

[GRCameron]

Could gear oil have been filled to the top of the case (via the left-hand plug) rather than to the level plug (one painted red - right-hand one in picture)? An extreme overfill would lead to overheating and leakage like you are seeing. Overheating would be from the oil being churned by the ring gears much like in a torque converter. I would also suspect the seal between the diff housing and the parking brake housing as this is very wet - more wet than the surrounding areas.

[pinzton]

Thanks for the hint GRCmaron. I'll check and will report back on the oil fill levels.

Reg. the seal between parking brake / differential: Can you tell me more?
(I remember before I had my breaking lines re-done there was a mention of oil dripping from the rear differential onto the parking brake. But I thought this was solved... Would love to learn more about this seal. I tried finding it in the drawing/part numbers... would you know?)

[undysworld]

Probably looking at #19 here: http://www.pinzgauer.com/parts.php?cat= ... view=03-01

If your previous work was to the hydraulic brake lines, they probably did nothing to this section of the truck.

[GRCameron]

Thanks for the hint GRCmaron. I'll check and will report back on the oil fill levels.

Reg. the seal between parking brake / differential: Can you tell me more?
(I remember before I had my breaking lines re-done there was a mention of oil dripping from the rear differential onto the parking brake. But I thought this was solved... Would love to learn more about this seal. I tried finding it in the drawing/part numbers... would you know?)

Although I haven't been into my diff/locker/parking brake assembly yet, I would be suspicious of any seals on the witches hat. The witches hat housing communicates with the differential housing through the bearing that supports the rear pinion. Gear lube can pass between the spaces, though slowly. The most likely problem is item 37, the Locker Housing Shaft Seal. The Brake Axle Shaft rotates in this seal and spins whenever the vehicle is in motion. The other seals and o-rings could be the problem, but they are mostly static or sliding seals and don't cycle frequently. Age could have taken its toll however, so check everything.

The fortunate thing is that you don't have to remove the rear diff from the vehicle. The tail cone does need to come off first and there is a body mount that is difficult to get to. It may require raising the body a bit. The parking brake flange and housing come off next and expose the rear witches hat (locker housing).

Someone may correct me here because of my lack of hands-on with the parts...

The picture is from SAV - Group 3-20

[GRCameron]

TechMOGogy posted this link to a very informative article in a topic that just popped up. Good stuff!

https://app.box.com/s/shf5gohckchubsolgvbg

viewtopic.php?f=13&t=9250


SAV part number for item #37 - Locker Housing Shaft Seal is 9023860