Differential Noise

[Steve P.]

Hey,

I drive a 06 M Coupe, after I shut off the car a hear a noise from the rear end (sounds like near the differential) sounds like a fan or pump running. Just wondering of this is normal, is it part of the M differential, cooling etc....?

[VitaminT]

My radiator fan runs after I shut the car off some time. Sometimes when I step out of the car you can hear it winding down.

[thekurgan]

In my 335i, there is a fan attached to the amplifier for the sound system, although I haven't examined the one for our thx system, it could be that as I don't believe there are any electronics in or around the diff on the Z4M.

[Car_Girl]

My 06 M Roadster had the same fan-like noise coming from the right rear. I had my local dealer take a look and they told me it was normal but I don't remember what they told me it was coming from.

My 07 MR doesn't have the same noise so the issue must have been fixed in the next model year.

[scottyD]

I have the same noise, but never asked the dealer about it. I always thought it had something to do with the fuel tank ventilation system and the carbon canister - a lot of that stuff is in the back right corner of the car.

Your differential doesn't have any pumps or make any noises like that when the car is shut off, and there's no coolant lines that run farther back than the heater core just behind the firewall.

Pretty sure it's fuel system related.

[skim]

Hey, guys. I recently started noticing this sound as well. It's coming from the rear and I'm not sure it's because it's been raining (weather related??). I didn't even drive it hard at all, just normal driving from work to home.
I just never really noticed this sound before. I know in my E90 M3, there's Premium sound system and it's got a fan attached, so it turns on at times, but since Z4 doesn't have it, I'm not sure what it is.
Reading this thread, I don't think people have found out yet what it is?
It shuts off after like 2-3 minutes.