Diff oil leak and smell

A

Attilio

Active member
 Dublin
Hello there,

I recently purchased a Z4M and learned how tail happy it can be when roads are wet, cold and the tyres old and nearly bald :wink:

I had the car checked by an official bmw dealer before purchasing it and no issue was detected apart from the need to change the tyres and the brakes being half way towards replacement. The oil diff was replaced only few thousand miles ago.

This evening I had the car MoT’d (in fact NCT’d since I live in Ireland) and I was informed there Is a leak from the diff. I also noticed a hot oil smell when I parked the car... :o

I confess that I indulged in some long power slides; I know it’s not proper but couldn’t help it :roll:

It the leak a sign of serious trouble? Any advice, things I should be looking for?

Thanks in advance,
A
 
My last ZM ( at 8ok ) went from dry diff to weeping within a few thousand miles , new seals nothing major , mine was passenger side ( its a backbox off job ) £180ish total iirc ? i certainly wouldn't be doing many miles until its sorted :cry:
 
mr wilks said:
My last ZM ( at 8ok ) went from dry diff to weeping within a few thousand miles , new seals nothing major , mine was passenger side ( its a backbox off job ) £180ish total iirc ? i certainly wouldn't be doing many miles until its sorted :cry:
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Yours was leaving oil on the drive from memory wasn’t it?
 
srhutch said:
mr wilks said:
My last ZM ( at 8ok ) went from dry diff to weeping within a few thousand miles , new seals nothing major , mine was passenger side ( its a backbox off job ) £180ish total iirc ? i certainly wouldn't be doing many miles until its sorted :cry:
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Yours was leaving oil on the drive from memory wasn’t it?
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Garage floor , zero oil drops from 9 months then parked up after a 300 mile weekend touring the Lake District passes ( for future reference i would never go over Hardknott Pass again in any car of my own ) next time it moved the oil drop was clear to see ( size of a 5p piece )
Spoke to my indy , didn't drive the car again until it was sorted as at that point there was no way of knowing what amount of oil was left in the diff .
The bill covered fresh oil , seal + labour
 
I might get a drip tray, just to remind me to check. It spends 300+ days a year in the garage so the best place to check it.
 
Thanks guys,

Will contact indipendent and main dealer to see who can fix it first; don’t want to take chances. Will keep you posted on the outcome. Wish me luck!

A
 
Agreed get it done, Once it starts it will get worse quickly- Well mine did anyway.

I went a bit OTT and took the diff out for a rebuild and all new seals :P
 
A knowledgeable BMW tech told me you want to get the diff seals done ASAP once you notice weeping. If the diff oil starts to sling around it gets onto the diff mounts it apparently causes the rubber to rot, meaning you would have to replace the mounts much sooner.
 
Mangozac said:
A knowledgeable BMW tech told me you want to get the diff seals done ASAP once you notice weeping. If the diff oil starts to sling around it gets onto the diff mounts it apparently causes the rubber to rot, meaning you would have to replace the mounts much sooner.
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Interesting as at the last England/Wales meet in April 15 there were a number of ///M's on the ramp from the forum at Dick Lovett where the dealer techs were looking over them. Nearl all if not all of them had weeping diffs/misting on the diff cases and the tech said it was common.
 
Thanks guys,

you scared me enough: leaving the office to go to BMW dealer to get an appointment... :cry:

will keep you posted; have a great weekend!
A
 
srhutch said:
Interesting as at the last England/Wales meet in April 15 there were a number of ///M's on the ramp from the forum at Dick Lovett where the dealer techs were looking over them. Nearl all if not all of them had weeping diffs/misting on the diff cases and the tech said it was common.
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Yes, it's extremely common on this diff. The weeping isn't the end of the world - he just knows I'm very particular about keeping my car mechanically tip top ;)
I wonder if there are improved seals available aftermarket?
 
bradz said:
Agreed get it done, Once it starts it will get worse quickly- Well mine did anyway.

I went a bit OTT and took the diff out for a rebuild and all new seals :P
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id do the same !! Over preventative FTW
 
All,

an update on the diff leak saga: my Z4MC is back at home with new seals on the differential (it was the one on the side of the prop shaft that was leaking very badly) and also with a new handbrake mechanism (yes, it was not working correctly and it had to be replaced).

I am a lot lighter having shed a pretty penny (loads in fact :o ) but the car is in really good shape now.

I nearly forgot: I also fitted two new Michelin Super Sports at the back (bloody hell they are really sticky compared to the old Contis!).

All good now :thumbsup: just have to find a way to earn more money! :wink:
 
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