Front diff pinion seal leaking again

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wolfpak110

Member
200TDI 93 D90.

Hi all, I have a front diff pinion seal that keeps leaking. I have replaced this seal twice already, recently, and used the LR tool and a LR seal.... So I assume the seal was inserted correctly and at the appropriate depth. I have checked the breather and its line- all clear. The flange appears to be in great shape too, no nicks or rust.

What could be making this leak again? Where else should I look for the culprit of this leak?

Thanks in advance!
 
Napalm00

Napalm00

Technical Excellence Contributor
have the little felt under the nut ? when you removed the other seals were they banged up ? maybe the diff is on its way out and rattling the seal to death./
 
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wolfpak110

Member
Thanks for the response. Ive pulled out 2 seals now, soon the third will come out. Both seals were in good shape with no damage. I havent gone any further into the diff because I have no idea what I am doing lol. Replacing the seal seems easy enough, but the bearing and other stuff seems more complicated. I am reviewing the parts diagram but truly don't understand it all yet.
 
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wolfpak110

Member
These are bad pictures, no matter what I did the light was too much. I think I see some pitting that didn't look too bad before but now with the input from you guys, I think it may be problematic. I will order a new one and go from there!




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Napalm00

Napalm00

Technical Excellence Contributor
Yeah there is a small groove there. I would just put in a new flange, comes as a kit with a new nut and seal.
 
D

dsh

Active member
Does it come with shims? He will have to set the preload; that's an envolved task for a beginner.
 
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wolfpak110

Member
DSH, no the kits dont have anything regarding shims. I've read quite a few posts here and on the DS forum and seen a few Youtube videos on it and I always thought that as long and you don't go into it deeper than the seal, the preload will be set by the nut torque. in other words, there isnt anything to set if you just change the seal and flange.
 
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dsh

Active member
I've been looking into this as my pinion seal requires replacing too. I'm not certain we can make the assumption the replacement flange will sit on the pinion in the exact location as the original when torqued to specs.
 
Napalm00

Napalm00

Technical Excellence Contributor
its fine , its not perfect but 90% of folks just mark the nut and pinion with a punch. remove the flange and spacer if present, and replace them torque the nut back to the mark.

ive done this at least 1x on my front diff over a decade of ownership and 600,000+ miles


if are really want to you can disassemble the front axle, remove the third member and check the pinon depth.
 
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dsh

Active member
That's good to know. Currently I'm looking for the quickest and easest method to replace the seal.

Thanks.
 
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wolfpak110

Member
Maybe that is part of my problem too, I didn't mark the castle nut because I thought it was just being torqued to 129nm or whatever the number is. ...and now it has come on and off several times. to make it more confusing, the new kit comes with the Nyloc. I will be torquing it to the appropriate setting, so we'll see how it goes with a new flange and nut.
 
Ren Ching

Ren Ching

Active member
Napalm00 said:
its fine , its not perfect but 90% of folks just mark the nut and pinion with a punch. remove the flange and spacer if present, and replace them torque the nut back to the mark.

ive done this at least 1x on my front diff over a decade of ownership and 600,000+ miles


if are really want to you can disassemble the front axle, remove the third member and check the pinon depth.
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pinion depth is irrelevant to pinion bearing preload. they are set by two different shim packs. You can change the pinion flange without worrying about messing up the preload, as the shims for preload are between the front bearing inner race and the pinion shoulder. There is no need or benefit to marking the pinion and nut. Just torque it correctly. If the bearings are a little worn but still serviceable, you can reset the shims using an inch-pound beam-style torque wrench.
 
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