2nd Pump on Brake Pedal - Virtually NO BRAKES!

[Fraz-ktf]

Hi.  I've had a scary issue with my brakes "Sometimes" having the feeling of "No Servo" almost - like you have to stand on the brakes to get any form of stopping power and even then, it's wholly inadequate.

I've recently narrowed it down to when it happens and I can now make it happen when I want.

If I'm driving along and I "Dab" the brake pedal, then immediately re-apply, that's when the "Failure" happens.  If I leave it a couple of seconds after the "Dab" then all is ok.  If I "Dab" then rev the engine then immediately brake, all is good.

any one got any ideas what the issue is?  I've just had the brakes bled to get rid of the issue but it still persists.

Thanks

[insanitybeard]

Sounds like a loss or reduction of vacuum supply to the servo- does the pedal go hard when the fault occurs? Servo vacuum pipe split near the terminations would be a favourite to check first, take a read back of this thread.

[Fraz-ktf]

Sounds like a loss or reduction of vacuum supply to the servo- does the pedal go hard when the fault occurs? Servo vacuum pipe split near the terminations would be a favourite to check first, take a read back of this thread.
[/uote]

Yes, the pedal is very hard, like when there's no servo (Morris Minor style ;-) )

I had a read back at my old thread, as you suggested (I didn't realise there had been further answers)

Has anyone got any photos of where / what the terminations of the vaccum pipe look like as I can't see them from the descriptions 

[SiC]

I've had this on a 2001 alhambra, as Insantybeard said check the servo. In my case a vac pipe had popped off.

[insanitybeard]

I've not got any pictures, but I believe number 1 on this parts diagram is the TDI vacuum (tandem) pump to servo pipe, the left hand termination goes into the servo (the hole to the lower right of the large circular drum shaped unit- number 3- in this diagram) and the right hand termination connects to the tandem pump (on the end of the cylinder head- number 1 here).

[Chrispb]

From my experience the connector on the back of the tandem pump is the most likely culprit also check the small vacuum connectors T'd to the large plastic pipe, one connector is usually blanked of with a cap which does perish the other is the vacuum supply to the boost valve's