View Full Version : Question Brake Servo Hissing when engine turned off - MK3 Golf TD

05-04-2009, 11:07 AM
Hi all
I've noticed a slight hissing noise coming from my brake servo area on my mk3 golf td (1994 - M reg) engine code 'aaz' when the engine has stopped running,is this normal ??
Thanks for reading.:beerchug:

05-04-2009, 12:34 PM
No not normally, sounds like you have a leak from it, the servo creates a vacuum. I have this on my old Polo once, it was actually the pipe, so i replaced it.
Does the car stall sometimes when applying the brakes?

05-04-2009, 05:28 PM
It won’t affect the engines running as it is a TDI and the servo is operated by an engine driven vacuum pump, not manifold vacuum. As Saunders says, check the servo feed pipe for splits after the check valve and I have seen Golf 3 servo’s rust through due to the battering they receive from debris thrown at them by the pulley/belt over the years. A new servo pipe is £19 from VW, part number 1H2 612 041 S.

05-04-2009, 07:32 PM
The car is the early TD version not a TDI.
Is the pipe plastic or metal & are they easy to fit ?
That is you don't need any special crimped jubilee clips at the ends ?
Would this pipe be visible in the haynes manual or does anyone have any pics of where it may
be situated in the car,as I wouldn't want to take off the wrong one.
Also,just out of interest could this leak make the brake pedal feel a bit spongy when braking ??
The cars had new fluid + discs + pads 1 month ago.
Thanks for the quick responses..

05-04-2009, 08:19 PM
....Also,just out of interest could this leak make the brake pedal feel a bit spongy when braking ??
The cars had new fluid + discs + pads 1 month ago...
You've probably answered your own question there. New pads and discs will take a few hundred miles to bed in, so, so long as the work was done properly, that is most likely what you are experiencing.

05-04-2009, 10:22 PM
Quite right, after all I own one; the I was a slip of the finger-your honour!

Anyway, it makes bugger all difference. The pipe is plastic, pushes into the servo (a smear of washing up liquid helps) and onto the pump it will have a crimp clamp or worm drive clip. It is about 1-cm in diameter and runs from the vacuum pump on the front of the engine where the distributor would be on an 8 valve petrol engine and all around to the back of the engine bay along to the servo which is the 9 inch diameter big black round thing directly in front of the brake pedal with the mater cylinder mounted on front of it. A leak on this pipe will make the brakes feel less responsive.