I have an oil leak from the front end of the sierra 7" lsd. I bought a seal kit which includes the pinion seal.
Having been under the car for the last hour and having removed the drive flange from the diff it seems the oil is not leaking past the seal by finding its way up between the splines of pinion and flange, past the securing nut and out. It is then flung sideways by the prop and pinion flange and blown back under the diff.
Should there be some sort of seal under the nut or front washer?

This board never lets me post pic in first post so its in my archive.

[Edited on 17/6/09 by Dusty]

diff leak

I'd use some non setting gasket compound then on the inner spline or make a paper gasket for under the washer

you might be needing a vent or if there's one already it may be blocked. The air inside heating up will force oil out if it can't vent the pressure out the diff case

[Edited on 17/6/09 by Mr Whippy]

A Dowty washer under the nut would most likely sort it if the face is good.

Mike

Had the same problem with mine a few weeks ago after a diff change,
The washer appears to be part of the diff flange my washer was loose but wouldn't come out tried sealer but still leaked
Ended up fitting another flange from a spare diif, the washer wouldn't move on this one and no leaks

The washer in mine also won't come out and rotates beautifully like it's on a bearing race. I don't have a spare diff flange. I was a bit surprised the flange came off the pinion without a puller suggesting some wear. Will try to knock out the washer and replace with something that will seal.
Thanks.

Severe beating will not remove washer so all cleaned in thinners to clean under the washer and reassembled with sealant on splines and forced under washer a bit. Fingers crossed. Design fault?