Noisy Diff - pinion bearings !! UPDATE.

S

sure2drive

Member
 New Forest, Hampshire
Hi all,
Just got back from my local Independent BMW garage, small but good team. Bought my 2.0i SE 2008 roadster 4 weeks ago with 45K and 3 owners, good history. Noticed a whine type noise when warmed up, coming from rear. Couldn't figure out what it was so asked garage to check. verdict "extreemy noisy differential pinion bearings on accelleration" . At the moment the noise is quite low when driving but it's frequency is just the right pitch to get on my nerves, and prognosis is that the bearings will get worse over time and fail.

So, what to do? new diff costs around £1000 plius VAT plus fitting, thats £1500 on a car costing £6000. Bit of a blow :(

Could fit a second hand diff for less, but how could I be sure it was any better? Can thses be rebulit/repaired, or is there any other option I might be able to consider.

Couldn't find out much at all about this on searching the forum (maybe I used the wrong criterea) and I wondered if this is a common problem, and what advice I may find, so I would be very grateful for others opinions.

Thanks in advance for any help.
 
Buy a secondhand diff. I've not heard of issues with diffs on Z4s so you'll probably be fine and save a load of money on a part that no-one sees anyway.
 
Private sale or dealership?

If latter take it back, if former opt for a reconditioned diff (you could probably pick one up for £400).

You touched upon it yourself, but can you really justify spending 25% of the value of your new car on a brand new diff?
 
Really sorry for delay in replying. I bought from an independent smallish dealer, and after checking with legal advice I do have 30 right of rejection if there is a fault, and after a bit of tooing and froing the dealer agreed there was. He offerred a full refund or said he would get it rebuilt by a decent automotive gearbox specialist (which I checked out) and give me a copy of the invoice for the 12 month warranty on the rebuild.( £450 plus VAT for all 4 bearings plus removal and re-fit.) That was agreed on Monday so it is with the dealer for this to be done. The rest of the car seems good as I have already had it checked locally which is when the fault was found, and I do like it, so fingers crossed the dealer who is the seller is as good as his word and I get it back soon.
So thanks for the help, I had no idea I had 30 right of rejection from a dealer so that was very helpful. My legal advisors have also been very good, so that helps when you have a difficult situation like this because I really liked the car and when I discovered this noise it really upset me because I thought I was lumbererd with it. I think if I ever buy a second hand vehicle again I will have it checked by an approved mechanic before I part with my cash, but luckily in this case it seems to be working out ok. Hopefully all will be well and in the meantime thanks again :)
 
Well the dealer sent the diff away for new bearings, and re-fitted it. I spoke to the repairer (gearbox and diff specialist) the bearings were pitted and worn, but he had seen far worse. I took it back to my indy BMW garage who said that they were much quiter and fine, so all should be fine with the diff.
I feel the noise is better, but I am still hearing a fairly high pitched vibration type noise at speeds of around 25 upwards. I can't figure out what it is so I'll do some more research to see if I can at least know where to look and if necessary maybe start another post for help, but at least a big step forward :-) :)
 
It's nice to see gratitude from people who have received help and advice :) I'm glad you reached a solution that seems entirely fair (and the bonus of a 12 month warranty!). The dealer definitely did the right thing here, so fair play to them. Let's hope this other sound is nothing to worry about :driving: Enjoy the car!
 
You could do with a z4 owner going for a ride with you to see if the noise is normal,there is tyre/road noise with the z4 roadster
 
Finding a noise source can be extremely difficult and a LOT of work.
I mean the diff is one possible source, but tyres, gearbox or propshaft bearing..... all related to speed/engine rpm and can sound like coming from the back.
My go to instrument is the engine stethoscope. But to listen to the propshaft bearing, it has to be set up rolling on a ramp (idling maybe in 3rd or 4th), remove the exhaust and heatshielding to get to the bearing, and maybe install the exhaust again to hear the bearing above the noise....
Thats 2 hours of work alone depending on the state of your exhaust.

Still its strange that I read loads of diff problems on this forum where it doesnt seem as much of a problem on the mainland forums. :scratchhead:
The bmw diffs are usually quite bulletproof and usually only get potential problems on very high mileage (above 200k miles)
(although the 2.0i has I believe a smaller diff than the other models)
 
GuidoK said:
I mean the diff is one possible source, but tyres, gearbox or propshaft bearing..... all related to speed/engine rpm and can sound like coming from the back.
Click to expand...
I second that. My E86 sounded completely different underway when I put a set of winter wheels on. I'd convinced myself that I had a problem with the diff up until that point because the noise seemed to be coming from the back and it was related to road speed.
 
Thanks for the comments, I know it is going to be difficult. Maybe it's just me and I am looking for problems where there are none, but at the moment it really is getting me down.
I was thinking the same thing as Maxman, I should find a Z4 owner near me who would take a ride with me and see if they noticed the same noise as me. I will see if I can find a local group, meantime, anyone near West side of Southampton who is willing to meet up please PM me?
Thanks again. :thumbsup:
 
Hi sure2 .
I also have had a noise on my car for about the last 3 years about 25mph and over never gotten any worse or any louder over that period of time .
I've spent well over £700 In parts and labour tryng to find it but eventually found it to be the rear tyres .
I have even gotten in the boot and had my wife drive the car while I listened .
I've found the noise does change slightly as the tyres wear . I've just put it down to being sat almost on the rear wheels and being a z4 quirk . :thumbsup:
 
I have even gotten in the boot and had my wife drive the car while I listened .


Sad bunny! :rofl: :thumbsup:
 
Thanks, I think that helps ?? :cry: At least I am not alone in this.
I can't say it's related to any of the runningrear really. It is a pretty constant noise, not loud but the frequency grates with me, it doesn't seem to increase with speed, stays the same when freewheeling , even gentle breaking. Sounds a bit like a fairly high frequency vibration, maybe whistling in a metallic sounding way?? wow trying to describe an irritating noise is really difficult!!.
I have stuffed the boot with a rubber mat and some old pillows and quilts to try and deaden the noise but that hasn't helped.
It just gets in my head and if I can't either establish it as "normal" or find the cause I may even have to sell it!
Recently regarding the Brexit vote they defined madness as doing the same thing over and over and expecting a different outcome, that's a bit like me at the moment. I keep wanting to take it for a drive to see if the noise has gone, and of course it hasn't.
I hope to find another owner not too far away just to have another opinon on weather I really am mad or not :)
Don't be put off though, I am not really mad, just want a second opinion without bothering my dealer again. :dizzy:
 
I know how you feel sure2 .
I had trouble defining what I was hearing . Had diff checked wheel bearings done blocked the drain holes up in case it was coming up the tube drove me nuts for awhile .
I stripped the boot and put sound deadening in all the places I could .
I found by accident a really smooth bit of tarmac on the m6 jct 19 and the noise was gone the tarmac had just been laid and I did a few passes and yes it was the rear tyres . :rofl: :driving:
 
Needs must pbondar,
As I couldn't turn round in the boot I had to do this twice to check each side . :cry:
My wife thought I was a little nuts but by then I was determined :D
 
Greg 01 said:
Needs must pbondar,
As I couldn't turn round in the boot I had to do this twice to check each side . :cry:
My wife thought I was a little nuts but by then I was determined :D
Click to expand...
:thumbsup:
 
I know Z4s' are prone to noisy diffs- my Z4 Coupe has had a bit of a whine , (particularly when I first get it out of the garage) since I got it over 3 years ago ( at 59000 miles) now on 74000 and its still there but not get any worse. I had a BMW indy change the diff and gearbox oils when I got it but, it didn't stop the noise so I just accept it as a "feature"!

Again, the DMF can be noisy when warm ( stops when pressing down clutch) but again got no worse over 15,000 miles and runs lovely so, again, seems to be an N52 thing , and researching it, even when people fork out for a new clutch/flywheel, it seems the noise makes its self known again, so I just live with it- and its not that bad- nobodys ever said to me- "bloody hell, whats that noise?" !!
 
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