Rear Differential Leak

[nicknick43]

New member.

So bought a car today only to get it home and see diff fluid leaking. Took a pic after I cleaned up the sludge and refilled. What seal or what else do I need to buy to stop this leak? I drained and filled but basically wasted money but I did identify the leak location if nothing else

 

[colb]

The Diff fill and drain plugs have alloy washers, over time these corrode and you end up with a leak. Did you replace these washers when you refilled? If new washers don't seal it then a few wraps of ptfe plumbing tape around the threads would solve it.
Gasket ring A22X27-AL x 2 Part No 07119963355 Item 16 in oem diagram below.
https://www.realoem.com/bmw/enUS/showparts?id=CM12-EUR-12-1999-Z3-BMW-Z3_19&diagId=33_0531

 

[nicknick43]

The Diff fill and drain plugs have alloy washers, over time these corrode and you end up with a leak. Did you replace these washers when you refilled? If new washers don't seal it then a few wraps of ptfe plumbing tape around the threads would solve it.
Gasket ring A22X27-AL x 2 Part No 07119963355 Item 16 in oem diagram below.
https://www.realoem.com/bmw/enUS/showparts?id=CM12-EUR-12-1999-Z3-BMW-Z3_19&diagId=33_0531

yeah those washers were in good shape after I cleaned them up. It’s leaking at the location in the picture which is opposite end toward the front of the car

 

[Tfp]

Your pic is a bit fuzzy, but that looks like it's leaking from the input seal.

I'd guess the diff will need stripping, and rebuilding to sort that.

Anyone done one?

 

[nicknick43]

Your pic is a bit fuzzy, but that looks like it's leaking from the input seal.

I'd guess the diff will need stripping, and rebuilding to sort that.

Anyone done one?

Sounds a job for a mechanic. Guess I should call a tow truck. Damn.

 

[Tfp]

Sounds a job for a mechanic. Guess I should call a tow truck. Damn.

There's a couple of people on here who break Z3's.

It might be better to just fit a used one that's not leaking rather than start stripping diffs down.

I'm sure someone will be along soon who's knows what to do for the best.

Maybe the seal can be changed in situ? I doubt it, but I've never stripped a diff.

 

[colb]

Had a look for a diy guide but only found one for the Z4, shouldn't be much difference than the Z3
https://www.pelicanparts.com/techar...RANS-Differential_Pinion_Seal_Replacement.htm

 

[nicknick43]

Thank you all. At a relatively trusted mechanic. Hoping it is just the pinion seal. Part is cheap. Labor is not as much. Fingers crossed.

 

[colb]

Seal change should do the job, only place it could leak from at the front, others are on the output shafts on the sides and of course the filler and drain plugs and rear cover plate. It should be doable with it on the car if its just the pinion seal with the right tools to hand.

 

[the Nefyn cat]

Or drop the back end and change all the bushes while it's down. But that way madness lies.

 

[nicknick43]

Found a used rear diff online. Installed. Car is on the road. Slow as hell but on the road. Haha

 

[Lee]

Done a few of these seals. Very simple to do once the diff is off. 4 bolts 4 nuts and two drive shafts later and your there

 

[dva99999]

Done a few of these seals. Very simple to do once the diff is off. 4 bolts 4 nuts and two drive shafts later and your there

Sorry to jump on this thread but I may have a problem with mine. What’s involved in replacing the seals at the side of the diff?

 

[Lee]

Sorry to jump on this thread but I may have a problem with mine. What’s involved in replacing the seals at the side of the diff?

Morning. Still pretty straight forward even with the diff left in the car.

1) empty the diff of fluid.
2) unbolt both drive shafts and leave to hang below the diff
3) unbolt the 13mm bolts holding the flange on. You have two seals, inner seal you tap into place and an outer O-ring.
4) do a side at a time because these flanges hold the LSD unit central. Worse case you just remove the back cover and hold the LSD unit up while you reseat the flanges.

I did this job on the bench on Dom’s low mile Z3 if you look in the Zedshed section.

lee

 

[dva99999]

Morning. Still pretty straight forward even with the diff left in the car.

1) empty the diff of fluid.
2) unbolt both drive shafts and leave to hang below the diff
3) unbolt the 13mm bolts holding the flange on. You have two seals, inner seal you tap into place and an outer O-ring.
4) do a side at a time because these flanges hold the LSD unit central. Worse case you just remove the back cover and hold the LSD unit up while you reseat the flanges.

I did this job on the bench on Dom’s low mile Z3 if you look in the Zedshed section.

lee

Will do thank you

 

[dva99999]

Morning. Still pretty straight forward even with the diff left in the car.

1) empty the diff of fluid.
2) unbolt both drive shafts and leave to hang below the diff
3) unbolt the 13mm bolts holding the flange on. You have two seals, inner seal you tap into place and an outer O-ring.
4) do a side at a time because these flanges hold the LSD unit central. Worse case you just remove the back cover and hold the LSD unit up while you reseat the flanges.

I did this job on the bench on Dom’s low mile Z3 if you look in the Zedshed section.

lee

I can just about see the part number 33107505602. Are there any other parts numbers as it does look like something I can do.

The reason I was concerned was because when I was removing the rear trailing arm I also removed the wrong bolts from the diff, unscrewing the 6 bolts closest to the diff instead of the Torx bolts which wouldn’t move. When I realised my mistake I slid the flange back in and screwed the bolts back in. But I’ve found that the flange slides in and out every time I try to remove the RTA (admittedly it clicks when going in).

Is this normal or are there screws that hold the flange in place?
cheers