touay001

Hi All.
I checked my timing belt tension last weekend on my S4 Auto. The belt was slightly on the lose side. After I adjusted the belt tension and reconnected the battery, When I started the engine I could hear an odd noise coming from the transmission. In reverse the engine sounds a bit rough, and the transmission produces a buzzing noise (simmaler to the fuel pump). It is normal in all other gears. The car drives very well in all gears. Has any one experienced some thing like that before?

touay001

Hi folks,
Have any one got any idea of what the buzzing noise is coming from?
Would it be related to cable adjustment?
I'll check the pinch collar bolts (front, and rear) this weekend.

murarie

Hi touay001,

I have a 87S4 with the same noise.

I think it must be half shafts or the Reverse Gear itself.

Murarie.

touay001

Hi murarie,
I toke the car to an auto specialist and he suggested it is coming from the pump. So I'll wait for a while before I drop the box.

Vlocity

This is more of an observation and may not apply since you seem pretty sure that the sound is coming from the underside of the car and the transmission....I did have a backup light relay which failed and would BUZZZZ
everytime I put the car in reverse. It took a little searching to locate that it was actually the relay.

My two cents worth....

Ken

murarie

Hi touay001,

Do you hear the sound when in reverse and the car held on brakes or when it is moving?

I hear the noise if i move the car in reverse.

Murarie.

tresamore

I have had non Porsche transmissions do that and it has been the pump on all of 3 them.

Barry Johnson

Mine does that in 1st gear, and goes away when I shift to 2nd. It seems to change in pitch when stopped in 1st too. Very well could be the pump with over 160k on it...
In thinking about it, I bet its that damn front pump that we always see leaking out of the o-ring.

touay001

Murarie,
The noise is there when the car is stopped and my foot is on the brake. The auto specialist said to me that it will go like this for a while before it gets any worse. I don't want to remove the transmission just for the pump. If I remove it, I'll do a full overhall.

M. Requin

I'm resurrecting this thread just to add that this is exactly what caused this phenomenon in my 928- replaced relay, buzz gone. NB: the auto relay is not the same as the manual trans relay, fortunately, the auto (for my year at least) is a 53. Search really is your friend around here!