Outer Limits 4x4 Board

About 2 months ago my rear diff pinion seal started leaking, NJ 3.5 diff. Diff had correct new oil about a year ago.

I have been checking the oil every week until i get the chance to do the seal, the oil has never been down any more than 10mm.

This week i have noticed the diff getting noisy, a decent whine whilst driving, disappears when you back off.

Checked the oil today, oil looked a little metallic, very bad. Immediate thought was that water had got into the diff.

so I dropped the oil, no water in the oil at all, but the amount of metal in the oil and on the magnetic bung , means there aint much diff left in there.

So, possible cause?

I have been told the crush washer behind the pinion can "crush" with too much abuse ??

The pinion bearing can collapse and cause the seal to leak 1st as there is a little movement then when it gets bad it will cause excessive tail shaft movement making the crown wheel and pinion gear mesh differently causing noise and can chip teeth etc.

lucky for you paj diffs are pretty cheap .. as they rarely get driven hard and so long as the tyre size is kept reasonable they are very durable ( especially the larger 3.5 unit )

just swap out the centre with a second hand unit ..

Well problem found.

I have a factory rear air locker in the rear. It is missing all but 6 of the teeth in the locker section.

The diff whine is likely a result of having so much metal in the oil.

Not sure what to do now, locker is a must. I dont want an ARB air leaker.

Have you been giving it a hard time with the locker in?

I shore all the teeth of my factory locker when giving it a bit of jandal a few years ago and replaced with with another one and now have gone air leaker (and yes, it is true to name). I would put another factory one in but not be as violent on the drivetrain as I was that day.

Yeh, It has had a hard time, though from what i have read if its properly engaged, it shouldnt break. So i was very careful about that.

Air leakers are a pathetic bit of junk, but they dont break teeth i guess.

I will pull the locker down tomorrow, and see what i can do about it if anything.

sick01 wrote:Yeh, It has had a hard time, though from what i have read if its properly engaged, it shouldnt break. So i was very careful about that.

Air leakers are a pathetic bit of junk, but they dont break teeth i guess.

I will pull the locker down tomorrow, and see what i can do about it if anything.

I have seen plenty of "air leaker's" last a very very long time and survive the backlash of busting chro-mo axles .. I would say that they are far from pathetic ..

They are pathetic because they leak, not because they break - from what i have seen they are the best part of unbreakable.

I know its on another forum- but a guy in sydney is selling a 9.5" diff out of a ML triton that has a factory locker.
http://www.newtriton.net/phpbb/viewtopi ... 30&t=11371
you might have to sign in to the forum $1000 but it is low kms.

you will have to use your 4.6 crown and pinion (as the triton runs a 4.1) diff ratio- hope your gears are in good condition.

Hi mate, thanks heaps for the tip off.

I now have an air leaker sitting here, i decided another factory locker may not last given how i like to drive.

So

$1100 ARB air leaker
$230 pump dr air
$30 pressure solenoid
$20 fuse and holder and relay
$10 tripple air fitting adaptor
$330 Diff centre bearings
= me feeling very broke!