Rear Diff Leak

f80_brian · 11-21-2020, 01:02 PM

Hey everyone!

Just got my first oil change and was looking under the car and saw that the rear passenger side diff was leaking. Does anyone know if this is a common problem, and if it's something I should get checked out ASAP? Also what is the estimated repair cost? Pictures provided below.

Thanks!

behindthen0thing · 11-21-2020, 01:27 PM

Common problem.
500-1000$

Stronie · 11-25-2020, 09:41 PM

Quote:

Originally Posted by behindthen0thing

Common problem.
500-1000$

TLG just posted a video on this. Seemed like an extensive repair, way more than $1000. Thank goodness for the warranty.

Tommy L Garage · 11-26-2020, 05:10 AM

I had a similar leak. Warranty covered it but it would have been north of $1000 to fix.
Leak was super small with no dripping on the garage floor. Just seepage.
Technically you can avoid the fix by filling up the rear diff every so often.

RoundelM3 · 11-26-2020, 09:26 AM

I had this problem - was a leaky seal on the passenger side. Caught it just before warranty ended, but my Indy shop said it'd be about $700 or so to fix. Might cost more at a dealership.

Fortyb · 11-26-2020, 02:01 PM

Quote:

Originally Posted by Tommy L Garage

I had a similar leak. Warranty covered it but it would have been north of $1000 to fix.
Leak was super small with no dripping on the garage floor. Just seepage.
Technically you can avoid the fix by filling up the rear diff every so often.

I have a very small leak also but plan on changing my diff fluid every 20000 miles.

sagi · 11-26-2020, 04:20 PM

Is there a particular mile/km range these leaks tend to occur?

Pinoyf80 · 11-26-2020, 06:32 PM

Quote:

Originally Posted by sagi

Is there a particular mile/km range these leaks tend to occur?

Usually 50k+ miles. Just had my diff serviced cause my right seal was leaking. My regular shop replaced both left and right.. now two months later my left one is leaking. Luckily they're covering me through warranty this time.

behindthen0thing · 11-27-2020, 01:50 PM

Quote:

Originally Posted by sagi

Is there a particular mile/km range these leaks tend to occur?

around 30K for me

BMRSEB · 11-27-2020, 06:28 PM

Mine was leaking too.. have about 45K when I noticed it. Had it “repaired” at dealership, thankfully still under warranty.. I will be checking it again as the standard factory warranty ends in December..

I will be scheduling a once over before that happens.. Car is CPO, so issues like this “should” be covered under the CPO, no?

I’ll be doing a visual myself this weekend just to see if anything’s going on back there..

White340 · 11-27-2020, 08:12 PM

So are they repairing this with the same or upgraded part? Would suck to have this problem again in another 30k. Miles

evo828 · 03-14-2021, 04:37 AM

Does anyone have a “how-to” guide for replacement of the seals? Seem to have a small leak on passenger side which occured after diff fluid replacement.

IB M · 03-14-2021, 10:30 PM

Quote:

Originally Posted by evo828

Does anyone have a “how-to” guide for replacement of the seals? Seem to have a small leak on passenger side which occured after diff fluid replacement.

Interesting - my 17 ZCP with 46,000 miles had no diff leak when serviced but then after at 49,000 miles it started to leak.

evo828 · 03-15-2021, 03:56 AM

Indeed interesting. I did the fluid change at 13ths miles when I bought the car. I spotted the slight oil leak now at 22ths when I was doing regular service/check. Might be that a small overfill caused it. i have now cleaned the diff and plan to re-check after couple of hundred miles again to see how much it leaks. I just wanted to get some info on how-to (to hand out to local garage) in case a re-sealing job will be needed. if it is too tricky/M4 specific - just better get them prepared.

evo828 · 03-15-2021, 02:38 PM

Attaching the manual for driveshaft removal/installation and diff seal replacement - if anyone is interested.

Jamongkad · 03-15-2021, 08:09 PM

I did a quick check on mine. What do ya'll think?

NickyC · 03-15-2021, 08:32 PM

LoL, amazing timing! Just noticed a small, maybe baseball sized spot on the garage floor right under the diff this afternoon. Time to make an appointment for warranty work!

Chances of being denied due to KW V3 slammage?

18 M4 Comp at 29k miles for reference.

IVM3 · 03-15-2021, 09:06 PM

Quote:

Originally Posted by Jamongkad

I did a quick check on mine. What do ya'll think?

That's roughly how mine looked and it was a leak. If the other side looks clean with no oil residue, then you know for sure it's slowly leaking.

Jamongkad · 03-15-2021, 10:52 PM

Quote:

Originally Posted by IVM3

Quote:

Originally Posted by Jamongkad

I did a quick check on mine. What do ya'll think?

That's roughly how mine looked and it was a leak. If the other side looks clean with no oil residue, then you know for sure it's slowly leaking.

Gotcha. Did you wait for it to be a full blown leak though? Or did you have it repaired asap? I am out of warranty already.

IVM3 · 03-16-2021, 10:54 AM

Quote:

Originally Posted by Jamongkad

Gotcha. Did you wait for it to be a full blown leak though? Or did you have it repaired asap? I am out of warranty already.

I fixed it right away but it's probably OK to wait a bit if you routinely monitor it to ensure it doesn't get significantly worse.

Jamongkad · 03-16-2021, 11:25 AM

Quote:

Originally Posted by IVM3

Quote:

Originally Posted by Jamongkad

Gotcha. Did you wait for it to be a full blown leak though? Or did you have it repaired asap? I am out of warranty already.

I fixed it right away but it's probably OK to wait a bit if you routinely monitor it to ensure it doesn't get significantly worse.

Yeah I was planning to just monitor it over time since the leak hasn't manifested itself fully.

11-21-2020, 01:02 PM	#1
f80_brian Private 34 Rep 80 Posts Drives: 2016 BMW M3 Join Date: Jun 2020 Location: Nashville, TN iTrader: (0)	Rear Diff Leak Hey everyone! Just got my first oil change and was looking under the car and saw that the rear passenger side diff was leaking. Does anyone know if this is a common problem, and if it's something I should get checked out ASAP? Also what is the estimated repair cost? Pictures provided below. Thanks! Attached Images
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11-21-2020, 01:27 PM	#2
behindthen0thing Captain 840 Rep 937 Posts Drives: M4 Join Date: Jul 2018 Location: Germany iTrader: (0)	Common problem. 500-1000$
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11-26-2020, 05:10 AM	#4
Tommy L Garage Colonel 2516 Rep 2,079 Posts Drives: 2017 YMB M3 6MT CP EP VP Join Date: Dec 2008 Location: Woodbridge, NJ iTrader: (2)	I had a similar leak. Warranty covered it but it would have been north of $1000 to fix. Leak was super small with no dripping on the garage floor. Just seepage. Technically you can avoid the fix by filling up the rear diff every so often.
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11-26-2020, 09:26 AM	#5
RoundelM3 Major General 1835 Rep 6,990 Posts Drives: 15 F80 M3, 22 G01 X3 30i Join Date: Apr 2010 Location: Clayton, NC iTrader: (2) Garage List 2022 BMW X3 [9.83] 2015 BMW M3 [6.50]	I had this problem - was a leaky seal on the passenger side. Caught it just before warranty ended, but my Indy shop said it'd be about $700 or so to fix. Might cost more at a dealership. __________________ 2015 F80 ///M3 Sedan 7DCT Tanzanite, 2022 X3 sDrive30i 8AT Brooklyn Grey
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11-26-2020, 04:20 PM	#7
sagi Private First Class 30 Rep 153 Posts Drives: F80 Join Date: Sep 2018 Location: Toronto iTrader: (0)	Is there a particular mile/km range these leaks tend to occur?
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11-27-2020, 06:28 PM	#10
BMRSEB Lieutenant 90 Rep 463 Posts Drives: M3 SR+ Join Date: Sep 2013 Location: Here! iTrader: (0)	Mine was leaking too.. have about 45K when I noticed it. Had it “repaired” at dealership, thankfully still under warranty.. I will be checking it again as the standard factory warranty ends in December.. I will be scheduling a once over before that happens.. Car is CPO, so issues like this “should” be covered under the CPO, no? I’ll be doing a visual myself this weekend just to see if anything’s going on back there..
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11-27-2020, 08:12 PM	#11
White340 Lieutenant Colonel 1392 Rep 1,986 Posts Drives: 2018 M3 Comp / 2022 X5 45e Join Date: Dec 2015 Location: NYC iTrader: (3)	So are they repairing this with the same or upgraded part? Would suck to have this problem again in another 30k. Miles __________________ 2022 X5 45e : AW/Tartufo 2018 M3 Competition : AW/SO 2016 340i xDrive : AW/CR (sold)
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03-14-2021, 04:37 AM	#12
evo828 Private 11 Rep 74 Posts Drives: 2016 BMW M4 Join Date: Apr 2020 Location: small town iTrader: (0)	Does anyone have a “how-to” guide for replacement of the seals? Seem to have a small leak on passenger side which occured after diff fluid replacement.
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03-15-2021, 03:56 AM	#14
evo828 Private 11 Rep 74 Posts Drives: 2016 BMW M4 Join Date: Apr 2020 Location: small town iTrader: (0)	Indeed interesting. I did the fluid change at 13ths miles when I bought the car. I spotted the slight oil leak now at 22ths when I was doing regular service/check. Might be that a small overfill caused it. i have now cleaned the diff and plan to re-check after couple of hundred miles again to see how much it leaks. I just wanted to get some info on how-to (to hand out to local garage) in case a re-sealing job will be needed. if it is too tricky/M4 specific - just better get them prepared.
	Appreciate 0 Quote

03-15-2021, 08:09 PM	#16
Jamongkad First Lieutenant 239 Rep 354 Posts Drives: 2021 BMW M2 F87 Join Date: Feb 2019 Location: Sacramento, CA iTrader: (2)	I did a quick check on mine. What do ya'll think?
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03-15-2021, 08:32 PM	#17
NickyC Lieutenant General 17474 Rep 10,662 Posts Drives: M4 CS. Former G82, x2 F82, F80 Join Date: Nov 2010 Location: Jacked out of my mind iTrader: (23)	LoL, amazing timing! Just noticed a small, maybe baseball sized spot on the garage floor right under the diff this afternoon. Time to make an appointment for warranty work! Chances of being denied due to KW V3 slammage? 18 M4 Comp at 29k miles for reference.
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