Rear Axle leak questions

[sandcobra164]

I searched and BFR did a great writeup / how to concerning replacing rear axle seals. The question I have is why is my axle leaking back through the brake drums? Is the keyway cork or RTV not applied properly as I see no other way for it to leak this way? Or do I have a more serious problem? Please advise as to why it may be leaking the way it is and I'll know better how to tackle the issue.

Thanks,

Joseph

Proud owner or an M35A2

 

[OD_Coyote]

My truck developed a leak and when I pulled the hub off, the cork seal looked fine.
I believe my leak was caused by a in-op axle vent. It is really important to remove and clean the axle vents (trans and xfer case too) periodically. Since the leak incident, I have replaced all the vents with new ones I purchased from White Owl Supply.

 

[velociT]

Mine was PACKED with so much GL1 it caused a leak.

Took it apart, cleaned the brakes and corrected the fluid level and no more leak.

 

[tiger422]

bad outer seal or cork

 

[Keith_J]

Mine was PACKED with so much GL1 it caused a leak.

Took it apart, cleaned the brakes and corrected the fluid level and no more leak.

And too much GAA in the inner hub will also do it. Remember, the inner and outer seals will try to prevent leaks but they will also allow pressure to build from heat. Usually, the inner seal will leak.

The usual "standard" was to FILL the hub with grease, I was told (by the 63Bs) that this grease was in case the bearings needed repacking in combat. But we are not in combat so just a THIN COAT inside the hub is plenty, any extra is never used and only gets squeezed out past the seals.

So, if you are doing a bearing service (3000 miles), clean the bearings/races, clean out the dirty grease and use the good grease in the hub, there should be plenty in there.

And lastly, get these trucks out at least once a week. This reseats the cups in the wheel cylinders and exercises the seals. Also, getting it to operating temperature once a month along with a complete PMCS is a great thing. You can skip the DA2404 . But make note of deficiencies, correcting ASAP.

 

[rsh253]

I had to replace all the axle seals on my M35 shortly after I got it because the air vents on both axle housings were plugged. When you add gear oil to the rear axle housings, don't over fill! After replacing the axle seals, I filled to the bottom of the filler hole. That's too much & one axle started leaking again. Use the old "one knuckle" rule: fill until the oil level reaches the tip of your finger when the 1st knuckle of your finger is at the bottom of the fill hole. (You want the oil level approx. 3/4" from the bottom of the fill hole.)

(There is an air vent on the top of the tranny & transfer case. Check those too.)

 

[sandcobra164]

Thanks for the advice. I checked all of my breather vents and the leaking axle's was plugged. I cleaned it, checked the fluid and it was a little high. The leak is not as bad now (not as much to leak out I guess) but it's still a Class 3. I checked the other axles and they are high as well. It does appear that both right sides and the rear left side have been into recently. The wheel cylinders look new and there's the tell tell orange RTV. Maybe they cut the seal on the threads on the leaky one when they were re-installed. As for greasing the bearings, I talked to one of my employees today (MCLB Albany) and he said that there's not much need for greasing the bearings since they are really lubricated by the gear oil in the axle. He also explained to me about the different seal kits available and suggested a brand that makes them in leather. Any thoughts?
​

 

[sandcobra164]

Disregard some of the last post. I pulled the offending axle shaft to find that the keyway had nothing in it (cork, rtv or otherwise) and determined this was likely my problem. In my excitement of having the truck mostly operational, I packed the keyway with RTV. I know that I still need to disassemble the hub and repack the bearings and replace the seal while I am in there but I put it back together to see if the leak will subside for the moment. I'll keep ya'll posted. I see now that the bearings should be greased and never see the gear oil as my friend had informed me!!! He had me convinced that the inner seal was the problem and that it didn't have an outer. Thanks to BFR for posting his writeup. The pics are very informative once I took the time to really study them.

 

[MWMULES]

sandcobra164 do you still have the link to BFR's writeup? I did a search for it and no joy. Thanks in advance.

 

[clinto]

sandcobra164 do you still have the link to BFR's writeup? I did a search for it and no joy. Thanks in advance.

http://www.steelsoldiers.com/deuce/5935-leaking-axle-seal-repair.html

 

[cattlerepairman]

As for greasing the bearings, I talked to one of my employees today (MCLB Albany) and he said that there's not much need for greasing the bearings since they are really lubricated by the gear oil in the axle.
​

​

Your employee is wrong for the Rockwell axle of yesteryear; it needs the oily and greasy bits separated by functional seals.

He is right for the commonly used modern planetary gear drive axles.

 

[sandcobra164]

Disregard some of the last post. I pulled the offending axle shaft to find that the keyway had nothing in it (cork, rtv or otherwise) and determined this was likely my problem. In my excitement of having the truck mostly operational, I packed the keyway with RTV. I know that I still need to disassemble the hub and repack the bearings and replace the seal while I am in there but I put it back together to see if the leak will subside for the moment. I'll keep ya'll posted. I see now that the bearings should be greased and never see the gear oil as my friend had informed me!!! He had me convinced that the inner seal was the problem and that it didn't have an outer. Thanks to BFR for posting his writeup. The pics are very informative once I took the time to really study them.

10-4, I spelled that out in this post last year.