BMW M5 Forum and M6 Forums banner

1 - 12 of 12 Posts

·
Registered
Joined
·
49 Posts
Discussion Starter #1 (Edited)
Been hearing a very unusual flapping sound from behind the dash, which increases with speed. Pressing the accelerator or clutch have no effect on the frequency, so it seems to be a speed thing (goes faster when I speed up). Took it to my indy who couldn't figure it out, thought it was the tires, or the catalytic converter (which was sorta loose, but that didn't fix the issue). I also shut the fan off and it was still there. I'm probably going to leave it back with my indy till he figures it out. Here's a video I made at night when it got quite loud, cruising at highway speeds:

M5 flapping sound 1/2 - YouTube

Any causes that I can suggest my shop to check out?
 

·
Registered
Joined
·
6,014 Posts
Sounds like the HVAC sampling fan to me, although that should be constant.
 

·
Registered
Joined
·
6,632 Posts
I would tend to agree with RAO as his expertise knows no limit. Plus it should be pretty easy to confirm by removing the HVAC controller. If the problem leaves with the controller and returns with it...Bingo!
 

·
Registered
Joined
·
3,605 Posts
That is the sound of money getting sucked out of your wallet. I thought everyone knew that one with these cars?
 

·
Registered
Joined
·
49 Posts
Discussion Starter #5
Thanks, just dropped it off again at my shop, this time for the full day and suggested the HVAC controller be checked out. Let's just hope it's a small fix
 

·
Registered
Joined
·
49 Posts
Discussion Starter #6
Still nothing! Agh this is annoying
 

·
Registered
Joined
·
4,488 Posts
Does the noise sound like it's coming from inside the cabin or outside? Because I think it's the centre support bearing on the drive shaft. It is notorious for making weird squeaking/clicking noises. If you get the rear wheels off the ground and get someone to run the car in gear to get the drivetrain spinning, you can listen underneath (carefully!), although this doesn't load the drivetrain.
 

·
Registered
Joined
·
49 Posts
Discussion Starter #8 (Edited)
Does the noise sound like it's coming from inside the cabin or outside? Because I think it's the centre support bearing on the drive shaft. It is notorious for making weird squeaking/clicking noises. If you get the rear wheels off the ground and get someone to run the car in gear to get the drivetrain spinning, you can listen underneath (carefully!), although this doesn't load the drivetrain.
It seems to be coming from inside (behind the dash/under the gearbox), but I say that because rolling the window down to hear it when it becomes prominent (60km/h+) the wind noise is louder. However, I'll ask for this to be checked out since it seems plausible!

Edit: I just looked up on the board, and saw a few videos, I think you may be right. I'll definitely ask for this to be checked.
 

·
Registered
Joined
·
49 Posts
Discussion Starter #9
Does the noise sound like it's coming from inside the cabin or outside? Because I think it's the centre support bearing on the drive shaft. It is notorious for making weird squeaking/clicking noises. If you get the rear wheels off the ground and get someone to run the car in gear to get the drivetrain spinning, you can listen underneath (carefully!), although this doesn't load the drivetrain.
You seem to be right, took it to my other shop, who immediately suggested the same thing before I said it. Hoisted it up, someone sat in the car to gas it and yes, it is coming from the driveshaft. Reading up the rest of the threads over here to see whats the best fix. They are trying to price either re-building it or putting a new driveshaft altogether. Let's see... thanks for your post!
 
  • Like
Reactions: 68FB

·
Registered
Joined
·
49 Posts
Discussion Starter #10
Reviving this old thread I had started, since the car has come out of winter hibernation, I got the driveshaft replaced, but the damn clicking noise is still there. It is now audible at lower speeds as well (it moves like a fan, and is slower at slow speeds, but goes faster at faster speeds). One other thing I noticed was vibration throughout the entire car at around highway speeds, kind of in conjunction with the clicking noise. Drove it on multiple highways to see if it was the road but it was the same regardless of road. Took it back to the shop who did the driveshaft, and they checked the tires, the brakes, control arms and bushings (which are less than a year old), and nothing seems to be the cause. FYI the old driveshaft was in need of repair, hence it wasn't money wasted getting it changed.

The car will be left with them on Monday to take apart. This is getting really really annoying now.
 

·
Registered
Joined
·
457 Posts
Your aux fan on the front of the car is ok? I had a similar noise when I replaced mine as the new part was not quite a perfect fit with the cowling - end up having to pull the cowling forward a few mm to stop noise with bonnet shut.

Noise sounds to be speed dependant rather than rev dependent...

Simon
 

·
Registered
Joined
·
49 Posts
Discussion Starter #12
Haven't thought about that, didn't think it would be relevant to this since typically that shouldn't be affected by vehicle speed but perhaps RPM or car temperature? I was under the impression since due to it increasing in intensity with the speed, it has to do with the driveline.

But at this point in time, might just give that a shot as well. Thanks
 
1 - 12 of 12 Posts
Top