939A2 rear axle hub oil leak

[Csm Davis]

Just noticed a oil leak around the CTIS fitting on my rear axle today. My ctis is not functioning so air pressure isn't pushing it out. Any ideas on what to look for?

 

[Ddmk18]

Are you talking about the fitting coming out of the hub that the valve goes on or the fitting that screws in the axle housing behind the backing plate for the brakes?

 

[Csm Davis]

Fitting on the hub on the outside.

 

[Ddmk18]

Probably the outer outside ctis hub seal. That's what mine was doing. It seals the gear oil out of the center section of the hub since the a2 outer bearing is a wet bearing and gets its lube from the diff.

 

[Csm Davis]

Probably the outer outside ctis hub seal. That's what mine was doing. It seals the gear oil out of the center section of the hub since the a2 outer bearing is a wet bearing and gets its lube from the diff.

Yet another reason I don't like CTIS, now I will have to tear into a hub.

 

[bevanet]

Mine is doing the same. Were you able to fix it? Any tips or part numbers? What did you have to take apart, the axel or just the ctis valve? Thank you

 

[Lukes_deuce]

My truck hasnt leaked from the outer hub, but I have teared into the front hubs on my 923a2. Not bad at all to replace the outer hub seal. Have to remove the tire, axle shaft and drum. Then remove seal and replace. But if your taking all that off, I would replace all the seals for the CTIS while your in there. Big mikes has a gasket kit for all the CTIS seals. Should also change the axle oil seal as well, which is just a little more work.

Just saw this was the rear hub, same idea for the rear.