Hi, I have a 2001 passat diesel 100bhp. The brakes in the car are really bad, the pedal is hard but the car slows down at a bad rate, also the car is very slow as the turbo is not working. I have been told in the past by a mechanic its down to my dual brake servo or dual cylinder ( i cant remember which one),…
Get a different mechanic!
If the brake pedal is firm but not stopping the car then the problem more then likely is the brake servo (booster) and when these fail it is often the fault of the brake master cylinder. But you have a turbo charger and both problems may be related. Such as a bad check valve or failed hose between the intake manifold and the brake booster.
Now the reason I suggest you get a different mechanic is this- parts warranties do not cover a booster when the master cylinder (dual cylinder) is not replaced. So if he just replaces the booster the odds are that you will be back in the shop in less then a year needing the master cylinder too along with another brake booster. It only takes a few more minutes to do both and labor to do the master cylinder includes taking the booster out.
I hate it when a mechanic goes for a half way fix just to drive labor costs up!
Old Man Dirt is almost correct – I agree that the two problems can be related. Only thing is that there is no connection from the intake manifold to the brake booster in a diesel car. It could be your vacuum pump that has failed, causing the turbo’s vanes to remain in one position and the brake booster to fail.
Easy test for the brake booster – turn the engine off, pump the brakes until the pedal goes hard, and keep it in. Now start the car – if the booster is OK, the pedal will feel softer and drop the rest of the way down.
So, in other words… check for vacuum leaks first, then check whether there is actually vacuum in the vacuum system pipes when the engine is running.
2001 Vw Passat Turbo