Pinion seal leaking AGAIN!
 

SOB, this is the third time in four years!

What the hell is wrong with this POS?

front diff of the drives, on the front. I notice that I can spin the pinion a bit, also I can slightly push it up and down.

Opinions? Thanks guys!

BTW, the vent is good. AFAIK.

Make sure the yoke doesn't have a groove worn in it where the seal rides, if it does you need to replace the yoke, or, if they still make them, get a seal that comes with a sleeve that slips over the worn spot on the yoke.

Also, that up and down movement on the yoke indicates either the bearing is worn or the pre-load on the bearing isn't right. That movement also could be wearing the seal prematurely.

Yoke was replaced last time the seal was replaced, if I'm not mistaken.

That's basically the answer I was looking for.

Is it a Meritor (formerly Rockwell) rear?

If so, those use a unitized pinion seal, similar to a wheel seal, where the inner diameter of the seal rotates along with the yoke, and the actual sealing occurs internally.

These have to be installed carefully, with the proper seal installation tool, or they can de damaged leading to short seal life.

Also, when reinstalling the yoke you have to be careful that it doesn't "jam" against the inner diameter of the seal as you are sliding it onto the spline, or the internal parts of the seal can be damaged, again leading to short seal life.

PTD wrote:I'll second that. If there is any such looseness, correct that before installing another new seal.

Also, even though you say a new yoke was installed, what about the splines on the input shaft?

If at one time the yoke came loose and pounded out the original seal, the splines on the input shaft could be worn just enough that the new yoke is gradually getting loose on the splines after many miles, leading to destruction of another seal.

When you check for up & down movement of the yoke, try to determine if the whole input shaft is moving up & down, or if the yoke is moving slightly on the shaft.

An easy way to check this is to look at the yoke retaining nut as you work the yoke up & down. If there is any relative motion between the yoke and retaining nut, then the yoke has come loose on the spline.

For what it's worth, I have seen instances of gear lube finding it's way along the splines and leaking out around the retaining nut due to a loose yoke also, even thogh the seal was still holding at that point.

excellent info, thank you very much!

I don't think it's the retaining nut, because the leak was behind the pinion, not the front of it.

ahhh, so don't even bother thinking about not replacing it? It's just automatic for you?

Thanks guys!

Allan you are going to have to pull that front diff out and have that front Pinion shaft replaced more than likely there is a grove worn in the shaft and regardless of whatever you do it is going to leak. Best bet would be put a reman diff in it and be done with it that way you get a warrenty with it.