Strange constant fan/motor sound

[HPsauce]

Not sure if this is engine bay or inside (heater/aircon) but you can hear it inside the car. It's annoying, worrying and perplexing.
Bonnet open and it appears to be central just in front of the windscreen under the big air intake.

It's a steady noise, but only there when the engine is running, does NOT vary in speed at all and nothing I do changes it, other than turning the engine off.
Turning the ventilation off makes no difference (it stays there) and it's not on if you turn the key, until the engine has actually started.

I'm running the ventilation in "econ" mode (no aircon) anyway until I get round to clearing the "orange" drains; at first I thought that might be related, but changing anything & everything on the ventilation makes no difference at all.

It sounds like a fan with a "slightly dodgy" bearing or with some dirt caught in it. Whether it started today or just got a bit louder I can't really say.
At speeds above about 40/50mph it's not noticeable (depending on the road surface noise).

Any thoughts anyone?

[IT]

Aux hot water pump. It is used for the resting heater and fails with remarkable success. It will create an awful bearing-like scratching sound like your engine just ate a spark plug.

It lives under the passenger side of the air intake.

I think I've documented it on here before.

It will spin up a second or so after putting the ignition on, and stays on.

The real test is to run the resting heater, which will also put it on. That should be pretty conclusive.

Not too expensive, couple of hours to change as its easiest done from the passenger side of the bulkhead with the glovebox etc removed.

A8parts are well aware of the fault and should have a replacement handy

[HPsauce]

Originally Posted by IT

The real test is to run the resting heater, which will also put it on. That should be pretty conclusive.

Thanks for the info. It was.

So what are the implications of not doing it immediately? Or can it be bypassed or turned off - I've NEVER used the resting heater until just now.

It's not a job I'd do myself either; is it something I could get a competent motor mechanic to do, or would I need a Audi specialist?

[IT]

Its just the bearings on the motor. We've known people just unplug the motor to stop the noise (quite easy to reach the cables from the engine bay side) and the only thing that seems affected is the resting heater.... The pump runs continously, but the heating doesnt seem harmed by not having it running.

I guess either specialist would do.

The motor is screwed on using two screws from memory, but these cant be accessed from the engine bay as the blower assembly is in the way.

By removing the glovebox, and then pulling back the carpet and acoustic foam insulation, you reveal the large square plastic cover which is held on by 4 hex nuts. Remove these nuts, remove that cover, and then my memory goes a little hazy, but remove what ever is under there to get reasonable access to the pump. undo the screws, remove it, stick another one in.

[HPsauce]

Originally Posted by IT

We've known people just unplug the motor to stop the noise (quite easy to reach the cables from the engine bay side) and the only thing that seems affected is the resting heater.... The pump runs continously, but the heating doesnt seem harmed by not having it running.

In the short term I think that's what I may well do.

Thanks for the info on access; I may well see how much a replacement is and get one in (from A8parts obviously) to add to the collection of "bits" that need fitting and minor things that need fettling "when the spring comes".

[HPsauce]

Originally Posted by IT

quite easy to reach the cables from the engine bay side

I'd say "extremely" easy.

Bonnet up this morning, turned on "rest" and it was immediately obvious where all the plumbing etc was, just to the nearside of the air intake.
There are 2 connectors right there, a "yellowish" one to the front and a "purplish" one by the windscreen, both just held by clips.

No tools needed, took maybe 30 seconds. Disconnecting the purple one stopped the pump.

I'll go back when it's a bit warmer (let's say above freezing) and tape up the exposed contacts. Then I'll give it a day or so and see if any codes show up on Vagcom/VCDS.

(note to self, sort out my paid-for Vagcom and get it properly transferred to VCDS on my Windows 7 laptop)

A8parts currently seem to have the full unit of pump, plumbing, valves etc. on sale but that's a bit pricey; will have to see if they just have the pump (assuming it's feasible to just swap that). Might even pop in to Amersham Audi and see what price they would charge for a new one.

[IT]

Give a8parts a call direct, there is a limit as to what they can can list on Ebay, but almost anything is possible if you have a chat with Carl

[HPsauce]

Originally Posted by IT

Give a8parts a call direct

Will do, I've sent emails in the past and had very helpful responses.

Now I know what it is it's gone onto my (rather too long) "to do" list so will have to wait a while.

Thanks very much for your help; where else could you get a car problem diagnosed (free!) on a Sunday evening after 9pm?

[ainarssems]

It looks like the part number is 4D0 959 617 C. Dealer price £859.72 inc VAT, ouch...

[HPsauce]

Ouch indeed.
That is the whole unit with valves and plumbing though.
There's a used one on eBay for £99 as it happens, quite near me.