Thread: D1 TDI Hard Brake Pedal

Originally Posted by JamesP

Hi all, my D1 TDI non ABS, has developed a brake problem where it has a hard brake pedal but takes both feet standing on the brake pedal to stop it. I doubt the brakes would lock up.
The wheel bearings are fine, no leaks and all hoses connected correctly. I performed the brake booster test and the result was when I started the engine the pedal did not go down at all. But there is no air sucking noise, all quiet.
Does this still mean the booster has failed ?
Any assistance on diagnoses and repair options appreciated.
thanks
James

Have you checked the stupid vacuum pump? Or the various hoses associated with it? Sounds like the pump to me, but many folk here will have other ideas.

300TDI Vacuum Pump stuffed

I agree it sounds like the pump is worn out.
I can assist you in replacing it if you can get to my place in crestmead, fairly sure I have a 2nd hand pump sitting in the shed to get you out of trouble.

Thanks for the offer jboot. With the engine running I did have some vacuum when removing the hose/ fitting from the booster. But maybe just not enough.
Will have a closer look at the pump.
regards

I just replaced mine. Roverload got a new one to me in Bundy overnight at the right price.

Paid for it Sunday night, despatched Monday, arrived Tuesday morning.

Another possibility is that if the master cylinder is dying and you are adding fluid all the time, the booster can become half full or more with brake fluid.

I had this on my 91 RRC and sucked out lots with a syringe.

Regards Philip A

Good, no ABS.

Vacuum pumps are pretty robust despite oil leaks and loose welch plugs. Contains several one way valves. If a valve goes in vacuum pump you may hear it rattling around, but more likely its in lots of small bits, and the unit will need replacing. The piston can detach from the push rod driven by the engine cam. The nut securing the piston to the rod can rattle around, but more like be put like a bullet through the cap - replace unit. You may have an effective vacuum pump, but lots of internal rattling - the guide for the push rod is secured by two secret grub screw, that can unwind - unwinding screws are no longer secret and can be seen when the unit is off the vehicle, and can be re-tightened. Otherwise, oil leaks around the head and through welch plugs should not stop it creating sufficient vacuum.

As already said, check for cracked hose between pump and power assist unit. Check the grommet adapter that connects vacuum hose to assist casing.

Start the vehicle to create vacuum. Turn off. Put head in drivers footwell and see if you can hear a 'hiss', this will be air filling your vacuum in the assist unit, ie a leak. Of course if leak is really bad then you may not get vacuum at all and no hiss by the time you get the head into the footwell.

Meat on the pads?

Less likely, but most of your calipre pistons are seizing through long term rust of chrome coating, muck build up. Temps around your 4 hubs uniform?

Others may be able to say, but do faulty proportioning valves cause brake hardness?