I replaced the rear pinion seal about 1.5 years ago and it started leaking again so my buddy put a new one in for me. And now that one is leaking too. Are we not getting them in correctly, or is something else causing the leaks? I checked the axle vent the first time I replaced it and the vent was clean.

 

Is there a groove in the yoke?

 

I'm not sure about that. If it is grooved do I need a new one or is there different size seals?

 

You can get a sleeve that installs over the yoke so the seal has something smooth to seal on. They work good, any parts place should be able to get one. They are called speedi-sleeves. A new yoke with U-bolts instead of the straps isn't that much more and is a better quality yoke.

 

Check the pinion bearing see if things are on the way out.

 

Make sure the axle-vent assembly isn't plugged with snot & rust. (A common thing that makes them leak all the time ).

 

If there's not enough pre-load on pinion bearing setup the pinion can walk a bit and cause early seal failure, before pinion bearing goes.

 

How does one go about checking the bearing preload?