Servo / Steering is making a noise on the A6.

Hello,

I have an A6 with a 130PS PD engine.
If you move the steering wheel while stationary, something will make a noise coming from the engine compartment. (This also applies when maneuvering.)
Initially, I thought it was the servo pump, because it was making a pulsating grinding/screaming noise.
(I once had a faulty steering rack, and it would make a similar screeching sound consistently while I was turning).
But as soon as you give it gas (even when stationary without driving), it disappears. I'm not so sure about that anymore...

It seems like the timing belt is slipping, but not permanently, but rather for about 1/4 of a second, and then again for 1/4 of a second, etc....

Has anyone ever experienced something like this?

I had also suspected the tensioner, but the timing belt is not flapping during the noise, which is what it should be doing...

Hoping you can understand the error.


Thank you in advance for your help.

Hi,

That sounds very suspicious, possibly due to the alternator failing. They tend to break down frequently in these engines. Check it out, and you'll have peace and quiet again. Best regards, Lois

That's right! That's something I hadn't thought of...


can the free run actually be checked? I have simply been replacing them so far...

Have you checked the servo oil level?

okay, I have already checked it

(but it's true that sometimes you simply forget the simplest thing)

the question is only how to test the free run...


I suspect that the error is not located outside of the free-running/spanner/servo pump.

Hi,

Remove the belt at the alternator (I think you should be able to remove it by lifting it up there. To completely remove the belt, you will probably need to bring the front into service position).

I usually do it this way:

Manuell den Riemen im Bereich des Lichtmaschinenantriebs hochziehen und ablegen. Dann hast du das Riemenscheibenrad der Lichtmaschine (also den Freilauf) vor dir. Drehe die Riemenscheibe kräftig von Hand und stoppe sie abrupt. Im Inneren der Lichtmaschine befindet sich das metallene Lüfterrad der Lichtmaschine (das man gut durch das Gehäuse sehen kann). Du musst dieses Rad genau beobachten, während du die Riemenscheibe abrupt stoppst. Konkret: Das metallene Lüfterrad muss sich in eine Richtung so drehen, dass es sich synchron mit der Riemenscheibe dreht. In the opposite direction, the metal fan in the alternator MUST run approximately 1-1.5cm further!! If, in both directions, everything comes to a standstill at the same time during this test, then your free-wheel is broken, as it has then become completely seized, and it can no longer compensate for the vibrations of your engine. This is what causes these noises. I personally believe that this defect is 99% likely. Best regards,

Yes, it was the free-running. It went in no direction anymore, not even with force...

The owner has had the car for about six months, and the engine has always run poorly. Now, after replacing the clutch, the problem is gone!

Absolutely incredible what this can achieve...

Thank you for the tips!