Brake pedal sinking on 2.0 TDi - BKD

[Jay Townley]

Hi guys, this is my first thread on here so, hello to you all. I'm not new to repairing cars as I have been restoring a messing about with aircooled VW's for the past 25+ years, and I'm an engineer so, I know how to turn a spanner and do basic maintenance .

I've got an issue with my brake pedal sinking to the floor, then after pumping, they work but go hard. If I rev the engine, the brakes come back and work fine. This has led me to think there's an air leak or vacuum problem so, I've replaced the vacuum pipes form the tandem pump to the servo and checked all other pipes for leaks, all of which appear to be ok.

Then I'm thinking a leaking brake pipe but, there's no evidence of fluid anywhere and certainly no drop in fluid from the reservoir.

If I pump the brakes with the ignition off 10/12 times, then wait for 10 seconds, the pedal drops significantly down so, now I thinking that air is getting in from somewhere.

It feels like when you bleed brakes, you apply pressure and your mate opens the bleed nipple, that kind of sinking if you know what I mean!!!

Has anyone on here heard of anything like this?

Thanks in advance


Jay

[RichardSEL]

Try a brake fluid flush and refill. With VW spec brake fluid (not DOT4) you have to change every two years irrespective of mileage.
Fluid must be to spec. VW 501 14-B 000 750 and marked as such on the can. Bleeding should include ABS unit

[martin1810]

Have the pads been replaced recently? This sometimes happens when someone changes the pads and pushes the pistons back without opening a bleed nipple.

[Crasher]

Has the hydraulic circuit been opened for anything recently?