My 2008 GTS has suffered with the PDCC hum since I can remember. It always seemed like something that could not be resolved but I woke up today remembering that the main line which runs to the reservoir vibrates..

So I thought, maybe, just maybe, that’s being transmitted through the car.

see the YouTube video.


https://youtube.com/shorts/YYMvcx6Agyc?feature=share

bingo.

Hum has gone!

I’ve got the bottle wrapped in a microfibre cloth but I plan to make an isolated bracket to properly resolve the issue.

I can’t believe I have put up with the noise for so long and it was such a simple fix. I bet every pdcc hum is this!

hopefully this helps some of you.

 

Isolator fix
https://www.onlinecarparts.co.uk/oen...brand%5B%5D=35
https://www.fcpeuro.com/products/bmw...t-17111113699l

And to really kick *** ...wrap it with some Damping Mat (get a small amount from your local car audio supplier)

 

Great to know!! Thanks for posting this

 

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I’ll try this soonest.


FWIW I replaced a clip that holds the pdcc line as it passes under the a/c compressor. It seems to have made things substantially better (more than I expected).

you may have snapped it during an oil change, like I did…

there are two more to check, visible from the driver front fender well, with the liner removed.

​​​​​​​p/n: 4D0616823

link: http://www.autoatlanta.com/tinyresul...=550&width=875



#5 in this diagram

 

Thanks guys!

My isolators are OK down below but I'll check those clips next.

I can't use one of those isolators for the bottle as it will sit the bottle too high, so I plan to extend the bracket on the car and use an isolator on the end of the bracket which will float the bottle from the car to fully stop it vibrating through. There are 2 contact points on the back of the bottle. A slotted area and the top fastening bit.

I'll report back once done.

 

Hi Mark

Well done on the diagnosis. I'm intrigued as to what's causing the vibration - the bottle is full of fluid. I wonder if the source is via the hoses? Have you considered adding a temporary damper to them or just a foam dampener behind the bottle/bracket?

 

FWIW this has no impact on the sound I get. There is clearly noise and vibration coming from the pump, on the PDCC side only, which can be felt by putting your hand on the hoses.

oh well, maybe a quirk to live with, and a $3000 lighter wallet, having paid to have the pump replaced.