Hi does anyone know where a humming drone noise could be coming from, its not the bearings have changed fronts and checked back ones, if I rev the engine while stationery there is no noise, if I coast in neutral it is stilll there so I think that rules out the gearbox. On the service instructions it says the diff is not a service item , the car is a 2013 e class 2.2 auto with rear wheel drive diesel it has done 47,000 miles and has full main dealer service history from new. thanks Alan

 

Does it happen at a specific speed, or all the time? Some other things to check would be the drive shaft center bearing, or unevenly worn/defective tires. In most cases the drive shaft center support bearing makes a hum or whine noise between 40-50km/h when it starts going bad but not at higher or lower speeds. A bad tire will get louder the faster you go, until the frequency gets so high you can't hear it.

 

Hi thanks for the reply I have fitted 4 new tyres i,t is a constant noise after I have travelled about 1/4 of a mile and slows to a deeper noise as the car slows down I was convinced it was the wheel bearings or tyres a t first but as I have said they have been changed. thanks Alan

 

Can you feel it? Do your brakes pulse? When you changed the tires, did you rotate the tire placement of the rims?

my thoughts:

first - rotate the tires. If the noise changed at all, then its a bad rim.

second - if your brakes are pulsating (warped), then replace the rotors and pads (look up fcpeuro) and search on here about the topic.

third - if one or two aren’t an influence, then you’re on a hunt for a bearing. The front diff is indeed sealed, but it is servicable via removal of the passenger side drive shaft. There is a fluid fill plug, but no drain plug. Put the car in the air and look down the tubes of the drive shaft towards the diff, see if you see any evidence of it leaking. If so, then the seals have gone out. Mine did that and had to replace the seals. Yes, the new gear oil made a difference in the smoothness factor.

if you can feel it, but cant tell from where its coming from, then I would look to the driveshaft center bearing and/or flex couplings.

But consider #1 and #2 before going on the hunt. If the brakes pulse, then chances are your pads are vibrating and that will definitely cause a drone noise. These aren’t like other cars whereby the caliper has a spreader clip. No, these pads just glide over the rotor 24/7, so any imperfection in the rotor will effect the pad’s ride regardless if being used or not. If you have drilled sport rotors, i would consider reolacing with regular rotors and nonmmetalic pads from fcpeuro instead. That fixed mine long ago.

but guess what, I just had my tires rotated with an oil change llast week. And guess what i hear again from the front oassenger side of my car at 70mph… i’ll give you a hint - its the title of your thread here. I have a bent rim yet again that i couldn’t hear when on the back, but can now hear on the front. Likely enhanced by an aging suspension system (9 years old) that hasnt needed a thing replaced.

 

Thanks I will check those points out.

 

Some new tires drone like mad...

 

Perhaps OP can find a very good friend with a similar vehicle, and swap front tires.