E91 325d Diff Help / Advise

Kev_G · 08-16-2016, 02:17 PM

My car has just hit 123k and the diff is whining

It did have a whine when I bought it I guess (thought it was a bearing) but 7 laps of the Nurburgring and 5000 miles around europe have increased the volume. Now its not getting louder but I am looking to possibly get one ready for when it does go.

Now as its a sealed unit I doubt the fluids ever been changed. I have seen a thread where a chap sucked the old fluid out and put new in. Would this help and is it worth a go?

Also I think I am looking at about £800 for a rebuild but would it be worth getting another one second hand to try first? If so where can i get one and are they the same on other models of car to mine?

I have a E91 325d (Jan 2007 build) so Pre LCI

Many Thanks

Kev

Digitalize · 08-16-2016, 03:21 PM

Oil isn't hugely expensive so it's worth a go. Whilst the oil is 'for life' the Diff isn't actually sealed from what I can tell, and does have a fill as well as a drain.

Phil325i · 08-17-2016, 03:18 AM

Quote:

Originally Posted by Digitalize

Oil isn't hugely expensive so it's worth a go. Whilst the oil is 'for life' the Diff isn't actually sealed from what I can tell, and does have a fill as well as a drain.

More likely fill but no drain. But you can suck the oil out with a hand pump. Lots of DIY vids on the web...

Digitalize · 08-17-2016, 07:00 AM

Having had a look, there is just one plug, and yeah it's a fill one, where you keep filling until it starts to pour out when the car is level, then the diff is full.

The best oil I could find was only £17 a litre and is still long life, potentially need two bottles to get to full. Tempted to get a cheap litre too and run that for maybe 500 miles before putting new Castrol in, just to help flush out the old stuff.

Kev_G · 08-17-2016, 11:48 AM

I know it wont fix my whine but think its worth doing then?

Digitalize · 08-18-2016, 05:05 AM

It might fix the whine, could be down to poor lubrication. Your diff might almost be empty or full of water etc.

wrongmark · 08-18-2016, 06:16 AM

Had same problem on mine at around 60k miles (immediately after I bought it). The dealer (non-BMW) got the rear diff bearings replaced after I complained. It has fixed the whine, but there's still a slight bit of a woosh noise at around 30mph. Mixed in with the road noise it's barely noticeable. I'm tempted to do an oil change as I recon they will have put the old oil back in to save a few quid.

Interested to know if the oil makes a difference for you.

08-16-2016, 02:17 PM	#1
Kev_G Private 1 Rep 55 Posts Drives: non Join Date: Jan 2016 Location: . iTrader: (0)	E91 325d Diff Help / Advise My car has just hit 123k and the diff is whining It did have a whine when I bought it I guess (thought it was a bearing) but 7 laps of the Nurburgring and 5000 miles around europe have increased the volume. Now its not getting louder but I am looking to possibly get one ready for when it does go. Now as its a sealed unit I doubt the fluids ever been changed. I have seen a thread where a chap sucked the old fluid out and put new in. Would this help and is it worth a go? Also I think I am looking at about £800 for a rebuild but would it be worth getting another one second hand to try first? If so where can i get one and are they the same on other models of car to mine? I have a E91 325d (Jan 2007 build) so Pre LCI Many Thanks Kev
	Appreciate 0 Tweet Quote

08-16-2016, 03:21 PM	#2
Digitalize Photographer 412 Rep 2,643 Posts Drives: 320D Join Date: Jun 2013 Location: UK iTrader: (0)	Oil isn't hugely expensive so it's worth a go. Whilst the oil is 'for life' the Diff isn't actually sealed from what I can tell, and does have a fill as well as a drain.
	Appreciate 0 Quote

08-17-2016, 07:00 AM	#4
Digitalize Photographer 412 Rep 2,643 Posts Drives: 320D Join Date: Jun 2013 Location: UK iTrader: (0)	Having had a look, there is just one plug, and yeah it's a fill one, where you keep filling until it starts to pour out when the car is level, then the diff is full. The best oil I could find was only £17 a litre and is still long life, potentially need two bottles to get to full. Tempted to get a cheap litre too and run that for maybe 500 miles before putting new Castrol in, just to help flush out the old stuff.
	Appreciate 0 Quote

08-17-2016, 11:48 AM	#5
Kev_G Private 1 Rep 55 Posts Drives: non Join Date: Jan 2016 Location: . iTrader: (0)	I know it wont fix my whine but think its worth doing then?
	Appreciate 0 Quote

08-18-2016, 05:05 AM	#6
Digitalize Photographer 412 Rep 2,643 Posts Drives: 320D Join Date: Jun 2013 Location: UK iTrader: (0)	It might fix the whine, could be down to poor lubrication. Your diff might almost be empty or full of water etc.
	Appreciate 0 Quote

08-18-2016, 06:16 AM	#7
wrongmark Second Lieutenant 98 Rep 256 Posts Drives: E90 320i, F31 328i Join Date: Feb 2016 Location: South Yorkshire iTrader: (0)	Had same problem on mine at around 60k miles (immediately after I bought it). The dealer (non-BMW) got the rear diff bearings replaced after I complained. It has fixed the whine, but there's still a slight bit of a woosh noise at around 30mph. Mixed in with the road noise it's barely noticeable. I'm tempted to do an oil change as I recon they will have put the old oil back in to save a few quid. Interested to know if the oil makes a difference for you.
	Appreciate 0 Quote