BMW Noise help appreciated

[Row 71]

Hi everyone, I have a 2011 BMW 318 2lt petrol with 41k and have a weird noise, when traveling there is a slight constant almost background noise, we have checked all brakes and wheel bearings even had the prop off to check the centre bearing and all seems good, its like a slight wheel bearing noise not a humming noise just a motion noise dose not get very loud when traveling just stays about the same also dose not change when you swing left and right like a wheel bearing fault may do but when you slow down to a stop it slows down with you, any advice or suggestions would be appreciated. 

[mike101 8]

Misshapen tyre? 

[Nick M.K. 574]

Rear diff possibly, I’ve changed 2 on coupes innthe lasyvyear, both low ileage. Also this Bmw 2ltr engines make a whiny noise at 2-4K revs, sounds like a high pitch metallic whine and it’s just how they are. Drive it to 40-50 Mph, then put it in neutral and let it coast to a stop. What happens with the noise? 

[D&M 66]

25 minutes ago, Nick M.K. said:

Rear diff possibly, I’ve changed 2 on coupes innthe lasyvyear, both low ileage. Also this Bmw 2ltr engines make a whiny noise at 2-4K revs, sounds like a high pitch metallic whine and it’s just how they are. Drive it to 40-50 Mph, then put it in neutral and let it coast to a stop. What happens with the noise? 

+1

We have changed a few over the years. The last one was a E90 320i M Sport

[Row 71]

2 hours ago, Nick M.K. said:

Rear diff possibly, I’ve changed 2 on coupes innthe lasyvyear, both low ileage. Also this Bmw 2ltr engines make a whiny noise at 2-4K revs, sounds like a high pitch metallic whine and it’s just how they are. Drive it to 40-50 Mph, then put it in neutral and let it coast to a stop. What happens with the noise? 

If I do what you say Nick the noise does not alter other than you can hear it slow down with your speed until you come to a stop

[Jack Regan 116]

Look at tyres .

[D&M 66]

47 minutes ago, Row said:

If I do what you say Nick the noise does not alter other than you can hear it slow down with your speed until you come to a stop

If you can jack up the rear and spin the rear wheels.

[EPV 631]

Check the tyres as an obvious and easy thing to do, correct spec etc. If all looks well then this is the rear diff. Common place with these. Changing the diff oil can help. 

[Tom 164]

I had a noise on an E90 turned out to be the rear diff, new bearings and crown gears fixed the problem £800 later. It sounds like a disc brake rubbing the backing plate. Very common on these rubbish german cars we no longer sell. Just check the tyres are not out of shape as well. 

[Tony F 38]

We have also done a couple of diffs on these. Nylon bearings apparently. But unusual for the diff to go at only 41k miles.

[Nick M.K. 574]

1 hour ago, Tony F said:

But unusual for the diff to go at only 41k miles.

Water condenses on the inside of these diffs in long cold periods of little use (I don't know how) and dilutes the diff oil which of course is "for life" so the problem is more common in very low mileage cars. On the plus side it's relatively easy to take them off and send away for refurb. 

[ExCouncilJobsworth 27]

Lots of clues  given about the tires but not how the tires might cause an issue....

If the "inside" of the tyre is put on the outside 

Or the direction of the tyre is opposite

It will make the noise you're describing. 

Look at all the tires carefully...and read Whats written on there 

[Stalker 180]

11 minutes ago, ExCouncilJobsworth said:

Lots of clues  given about the tires but not how the tires might cause an issue....

If the "inside" of the tyre is put on the outside 

Or the direction of the tyre is opposite

It will make the noise you're describing. 

Look at all the tires carefully...and read Whats written on there 

They also can go stepped on the inside edge, get your hand in and feel around  the circumference and feel if they are lumpy? This gives off a horrible noise like a diff/bearing. 

 

However tge bearings in the in the rear diff are of a lesser quality than those in my 3 year old sons scooter. 

[tradegirl 112]

On 12/9/2018 at 8:33 AM, Nick M.K. said:

Also this Bmw 2ltr engines make a whiny noise at 2-4K revs, sounds like a high pitch metallic whine and it’s just how they are.

This. Drives me nuts, but it's just how they sound apparently.

[Row 71]

Got this sorted thanks for your help, turned out to be the diff, I managed to get a good used one for 150 and very easy to fit, thanks everyone for your input.

[Tom 164]

3 hours ago, Row said:

Got this sorted thanks for your help, turned out to be the diff, I managed to get a good used one for 150 and very easy to fit, thanks everyone for your input.

Well done, I couldn't find one for love nor money on my 2010 320i saloon, apparently BMW changed the ratios on certain years so it had to be the same. 

[Row 71]

Yes Tom I managed to get one same ratio no problem, my gearbox man could have recond it from 250 upwards depending on severity of wear, that would have been my option 2.