mysterious read diff oil leak on Discover 1

[ishapiro]

I am chasing a repeating oil leak with my rear pinion seal on the Discovery 1. The truck has 125K on it and had the leak when I bought it. I have replaced the seal several times and eventually replaced to the new type flange & seal (STC3723) and also put a new breather. All the seals started leaking after just a few thousand km. Any ideas?

Thanks!

[discojonny]

It could be your output bearing is bad and creating play at the seal. how is the surface on the shaft where the seal runs? If it is grooved or corroded it could be wearing the new seal.

[ishapiro]

I haven't noticed excessive play in the pinion when I was replacing the seals. Last time I replaced the seal together with a new flange (came in a kit STC3723). This was about 1500k ago.
How do I check if this bearing is good? How hard is to replace it, do I need to take the whole diff casing apart?

[island dormy]

Hello

When you put the new seals in did you pack the back of the seal with grease or at least oil the new seal. Installing a new seal dry will destroy it very fast.

The surface the seal runs on also has to be perfectly smooth.

Good luck. Victor 1962 Dormobile

[ishapiro]

The seal came with some grease on it and as far as I remember I also put some extra (at least that is what I did in the previous attempts). The last time I installed it I also installed a brand new flange so the surface should have been smooth (I visually inspected it and it looked good). I also installed a new breather.
I tend to think perhaps something is not centered properly on the pinion causing it to slightly vibrate when driving and over time that would destroy the seal, correct? Although I haven't noticed any play when I installed the seal.
Would the bearing be worn at that mileage 125Kkm? How hard is to replace it?

[island dormy]

Hello again

I am not sure if a Disco pinion seal and pinion bearing are the same as on a series (which I have replaced) but there should be no up and down movement or in and out movement of the pinion.
I would think that if the bearing was going bad you would have lots of noise coming from it.

Are you tightening the pinion nut up to the specified torque? (you will need the park brake on full the vehicle in gear or park and the wheels chocked).

What brand of pinion seal are you using?

Any way thats all I can think of

Good luck Victor

[red90]

The bearings are supposed to be preloaded, so there is zero play. If there is play, a bearing has gone bad. You need to pull, replace both pinion bearings and setup the diff....