Leaking Diff

[vkicera]

I have a Stewart & Stevenson M1090 with a leaking diff. It appears to be coming out of the breather, would the CTIS cause pressure to push oil out the breather ?? Would it be a seal problem ??

Thanks for any help.

 

[f8617]

FWIW -- I didn't have a noticeable breather tube leak with CTIS seal failure.
Instead, CTIS seal leak caused the threads on the hollow CTIS wheel lugs to be damp from gear oil.
Also, the inner wheel seals failed, allowing CTIS air to force gear oil to leak on the hubs and brakes.

 

[Suprman]

Which breather? Usually the axle breathers are plumbed into the ctis air release system.

 

[vkicera]

I'm not sure, I need to check it out better. It looked like the pinion seal at first but I was told it was probably the breather, but you're right about them being plumbed into the air release. I suppose if it had a bad CTIS seal, the air would go out the breather. Is there any other way the pressure could force oil out the pinion seal?? I would not think there would be that much oil in the upper part of the diff for it to produce a significant leak

 

[Suprman]

Is it just seepage or is it dripping? Can you post a pic?

 

[vkicera]

I just got the truck and when I drove it, oil got sprayed around from the front rear diff drive shaft input. I thought it was coming out of the seal but the former owner said that he thought it was the vent. leaking on the input flange and spraying around. He said that it didn't leak when the CTIS was disconnected. The CTIS was set on Highway and the light kept flashing, I assume it has a seal leak but didn't know if it could pressurize the diff and blow the oil out.

 

[Suprman]

At the transfer case or axle? Is the ctis sending air? You would hear it. Oil is not supposed to come out when driving. I wouldnt drive it till its fixed.