Loud noise over 100km

Shane732

I'm hoping some of you might be able to help me out.

I've an E93 BMW 335i. When I'm driving over 100km I tend to get a loud droning noise. I've had the exhaust looked at and it's fine. I don't think it's a wheel bearing either.

Any suggestions?

spiggotpaddy

could be the diff.

dooroy

Does the sound change if you release accelerator for example and let the car coast ?

tossy

Tyre brand and condition ?

Shane732

tossy wrote: »

Tyre brand and condition ?

Bridgestone and 5mm at least - runflat though

Shane732

dooroy wrote: »

Does the sound change if you release accelerator for example and let the car coast ?

It changes when I let the speed drop below 100km but I still get the noise when coasting above 100km.

porsche boy

diff or wheel bearing

dooroy

If you could find a stretch of straight road clear of traffic and gently turn the steering from side to side - see if sound changes . This action transfers the weight of the car from side to side - and if the sound changes it could indicate a wheel bearing . As you turn to the left the weight is transferred to the 2 RH wheels and vice versa.

In my experience the noise from a diff changes from drive to overrun. Also check to see if there is any sign of a leak from the diff - could be low in oil.

As regards the tyres they can cause all kinds of noises and be hard to pin down. Due to their very strong sidewalls one of the runflats could be causing it.
If you could jack up each wheel and spin it you could check if the tyre has begun to deform (maybe due to previous damage ). Spin the tyre and view it from various angles . I have seen people change wheel bearings - when in fact the tyre was the problem .

Shane732

dooroy wrote: »

If you could find a stretch of straight road clear of traffic and gently turn the steering from side to side - see if sound changes . This action transfers the weight of the car from side to side - and if the sound changes it could indicate a wheel bearing . As you turn to the left the weight is transferred to the 2 RH wheels and vice versa.

In my experience the noise from a diff changes from drive to overrun. Also check to see if there is any sign of a leak from the diff - could be low in oil.

As regards the tyres they can cause all kinds of noises and be hard to pin down. Due to their very strong sidewalls one of the runflats could be causing it.
If you could jack up each wheel and spin it you could check if the tyre has begun to deform (maybe due to previous damage ). Spin the tyre and view it from various angles . I have seen people change wheel bearings - when in fact the tyre was the problem .

Thanks for this. Could well be the tyre.

I find that I get the noise when driving in a straight line and not necessarily when cornering etc...

9935452

it could be worth checking / changing the oil in the diff .
Its something i would do regardless of the droning noise

irish gent

Bearings to the rear maybe

Shane732

So the tyre is deformed. It's bulging on the inside.

I'm working what could have caused it? Bearing?

Special Circumstances

Is your run-flat running... flat... ?

Shane732

Special Circumstances wrote: »

Is your run-flat running... flat... ?

Nope - it's fine.

dooroy

Tyres can deform for all kinds of reasons - pothole , kerb (any kind of sharp edge) and if they run at low pressure for a while they can heat up excessively causing the rubber to 'soften' and allow some of the cords to move .
Often it is something that just happens - the danger is that if its on the inside of the tyre it can go unnoticed and eventually lead to blowout etc .
Worn shocks can cause a tyre to become worn in patches but wheel bearings don't usually affect the tyre .