rear diff buggered

[sick01]

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 ??

[Beer Baron]

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.

[Guy]

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 ..

[sick01]

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.

[NJV6]

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.

[sick01]

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.

[Guy]

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 ..

[sick01]

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

[4wd26]

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.

[sick01]

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!