Where to purcahse a power steering pump on the way out.

What makes you think that it is the power steering pump?

It is not exactly "behind the dash" and if on the way out it normally is noisy continuously (as it is running all the time anyway).

If you can pls take a video/soundfile of what you hear. Behind the dash is e.g. the windscreen wiper linkage which has a motor attached that can make noises (variable pressure for driver side wiper) and the flaps motor within the dashboard also sometimes seem to have a noisy life of their own.

If you´re already low on Pentosin due to it leaking then it might indeed be a noise coming from the p/s pump (air bubbles leading to noisy cavitation). This does not necessarily imply it being on the way out but rather indicates a low oil condition which should be fixed sooner than later. I´d have the leak fixed, topped up Pentosin properly (pls inform your workshop how this is done, they´ll likely overfill and you will have more Pentosin dripping...) and check again.

Cheers
Reinhard

Hard to hear

Just to make sure I understood this correctly: upon switching off the engine it starts right away, meaning the engine is OFF and then the noise appears?
If yes, then the steering pump can definitely be excluded as it is belt driven and will only work with the enigine running.
Further from there I´d assume it is a flap motor (there are a few underneath the dash). (Air) Flaps get a signal to shut when car is turned off IIRC.
Those flaps are rather difficult to get to and from memory some may require the dashboard to be taken out to get to them.

Cheers
Reinhard

Wow

That sounds pretty nasty indeed. Will this also happen with the car idling in standstill or does it require the car to be moved?

If it requires a moving car pls get a 2nd person to turn off the engine and you listen from outside with the hood open whether it comes from the base of the driver side wiper and is thus transferred to the interior.

Here is a scheme of what I am thinking about:

8er.org/forum/index.php?attachment/22216/

Motor #10 sits underneath the driver´s side wiper axle and is used to increase blade pressure to the windscreen the faster you go. Methinks that this motor does make a "calibration run" of sorts after starting the engine and will return to a base setting when turning off the engine. This is guessing though - one of ours has a 2 second "motor running" noise, not that nasty but exactly where yours seems to emanate from about a minute into driving and this will also return upon switching the engine off. I do not recall whether any of the other cars does this but never thought about it much anyway because it sounds a lot healthier than yours

Keep us posted!
Cheers
Reinhard

I don't think this sound comes from the wiper pressure control. I see no reason why it should do a calibration run or something like that every time the engine is started. Anyway, this is very easy to test: Between the fresh air cowl and the water valves assembly is a large round connector. Disconnect it to disable the wiper system completely. If the noise is still present after doing so, you can safely rule out the wipers.

Thx for chiming in... I never went to the length to really check for that source of "noise". It is in a car which I rarely use and hear it after more or less 100 m of driving - have been hearing it for so long to not be bothered at all.
I also seem to remember it appearing once the engine has been turned off. It is in a very similar location though to the one Richard describes only on the other side of the car as his car is RHD! Hence I am tempted to point towards the only thing I know is right in front of the drivers dash in LHD and RHD cars and somehow mechanically linked to be able to transport such noise into the cabin. Nevertheless it may just as well be a flap motor - there is enough reason to believe that the IHKA opens flaps after some driving and shuts them when the car has been turned off.

It´s Richard´s turn now

Reinhard

+1 with above comments about listening under the hood.

It sounds like a seventy’s ford escort cranking over. Could something be catching, like a fan blade?

Soz pushed infront of Richard:~)

Sounds just like when the magnets came loose inside my Aux fan

Wez

Richard.H: Did you test disconnecting the wipers like I described above? Even though I don't think the noise is coming from the wipers, as long as you cannot pinpoint the exact source location, you'll have to eliminate components by deactivating them.

If the noise is not coming from the wipers, remove fuse F21 in the front power distribution box and repeat the test. This removes runtime power to the IHKA module and should disable the air flap stepper motors.

Update: The above is not relevant anymore because Richard updated his post and managed to locate the source of the noise to the E-box (fan).

I was thinking about the E-box fan as well, but discarded that thought when you wrote "when the engine is switched off the noise is activated almost immediately starts for 7 seconds then stops". Why would the fan start after switching off the engine? In fact, when you switch off the engine you immediately cut power to the fuel pump relay(s) which on its turn cut power to the e-box fan. Or could it be a fan spin-down sound you hear when you switch off the engine (and spin-up sound 60 seconds after starting off)?

Anyway, the E-box fan is definitely something to investigate. Here's a good post by 8Tech on how to get access to the fan: ECU / DME Fan replacement procedure?! (RHD).

I´d be surprised. The E-box fan is but a wimpy computer type fan.
Pls follow Revtor´s advice to disable anything related to the wipers and then IHKA.
My money is still on the pressure adjusting motor underneath the driver side linkage ... and very close to the E-box in RHD cars

Keeping my fingers crossed that you manage to nail it down quickly...
Reinhard

Richard, for our RHD cars its the big round connector (like the diag connector) right next to the Batt+ jump point....

Oops just remembered you have the V8.... the v8 jump post is on the other side....

the wiper connector its here:

8er.org/forum/index.php?attachment/22311/