When I start the car it makes a small but obnoxious humming noise... coming from the driver's side near the wheel. I assume it's the air compressor but it's never sounded like this that I have noticed. The air suspensions seems to be working just fine. Anybody know what's going on? Air compressor going out or is there a service it may need?

 

The suspension air compressor is in the rear of the vehicle, the vacuum pump is located in the left front wheel well.

 

This one is in the front so must be the vaccum pump. Does yours make much noise? Mine seems to just now have become noticeable?

 

Hi.

Whilst I had the leaking vac hose, my pump was working harder and eventually got noisier before finally burning out.
Then again, it's possible for it to just get tired and worn out anyway I guess.
The Audi A8 has the same pump by the way, same numbers on it, so you don't need to pay the extra for a Bentley box.

Les.

 

Hopefully it's just the pump and not a leaking hose... it's a 2007 and I know the leaks on 2007 were not very common. I took it to the shop today and they're going to run a smoke test on Monday. I'll post an update when I know Monday!

 

I'm not having any leaking sounds... just seems to be the a loud pump I haven't heard before, fingers crossed it's just a pump going bad.

 

I don't want to put a damper on it but, you won't necessarily hear a hissing sound if there's a leak. I didn't hear anything on mine.
It's vacuum not HP air.
I wish you good luck.

Les.

 

i should have said the pump doesn't stay on all the time. I honestly never even heard the pump til lately. I'll update you on what the smoke test shows tomorrow.

 

FWIW,
I got a distinct whining noise when the car had less than 10.000miles on it. Dealer had it fixed and said it was a tension-pulley at the fanbelt.......
One year later same whining noise on left between radiator and wheelarch.......I went over the fluids and discovered that hydraulic (power steering) was low. Topped it up and never had the noise again....maybe worth looking into that.....
C.

 

was the noise coming from inside the driver's side fender?

 

Vacuum leak... I'll know more tomorrow. He said it's possibly coming from "that plate on top of the pump" not sure what that means, but I'm going by in the morning.

 

This is a picture of the Vacuum pump assembly. The hoses are at the top and the pump outlet hose at the bottom.
It sits inside the left wheel arch liner in front of the door hinge area.

Les.

 

Turns out it's just a loud vacuum pump... so the pump is probably about to go. My Indy dealer quoted me a $500 pump plus 2 hours labor

 

Like I said, it's an Audi/VW pump. The last letter denotes the year, so A is earliest, etc.
It's not too difficult to swap.

There are lots on eBay UK at the moment if you want a used one. Here's a link; http://www.ebay.co.uk/sch/i.html?_od...27317&_sacat=0

 

So all the pumps are the same... a4, a6, a8, etc???