Hi
I have a 1999 TD5 Defender 110.

I have had on going brake problems.
My brakes are going from having full travel on the pedal with little braking, to a rock hard pedal with very strong braking (and every variant in between).
Sometimes, when started, I have very little, and then gradually the braking comes back, or the opposite can happen.
The calipers are good and clean, the pistons are relatively new. The pads are good.
There is no loss of brake fluid from the reservoir, or any signs of leakage around the master cylinder.
It seems then that I have a servo issue???
Is this likely to be the servo unit which is directly behind the master cylinder, the servo pipe, or even the servo pump which I think connects to the alternator??
Is there a simple way of testing what is at fault??

Many Thanks.

servo can be checked by pressing brake pedal hard holding pedal and switching on engine vacuum should allow pedal to go further down , does fluid splash up in res when pedal pumped ,is there a black deposit on bttom of res , its quite poossible for m/c seals to intermittently leak without fluid loss ,likewise in the rest of system it can suck air in on pedal return but not leak noticeably on pressing , if a servo has or cant hold a vaccum pedal will be very hard braking effort poor

jamesmartin said:

servo can be checked by pressing brake pedal hard holding pedal and switching on engine vacuum should allow pedal to go further down , does fluid splash up in res when pedal pumped ,is there a black deposit on bttom of res , its quite poossible for m/c seals to intermittently leak without fluid loss ,likewise in the rest of system it can suck air in on pedal return but not leak noticeably on pressing , if a servo has or cant hold a vaccum pedal will be very hard braking effort poor

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Hi James
I have just tested my brakes as you mentioned above, and with the reservoir top off, and the brake pedal pumped with the engine on, there is a large splash. It looks like lava of a volcano erupting!!
What does this mean (air getting in I presume??).

Thanks for your help.

poor master cylinder seals is usual cause ,its not uncommon for them to go while bleeding braking system

jamesmartin said:

poor master cylinder seals is usual cause ,its not uncommon for them to go while bleeding braking system

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Thanks James

Can I buy the seals separately, or do I need a new master cylinder???

stc441 is m/c for non abs and sjc100420 for abs upto vin xa as far as i know no seperate seal kits are available, m/c isnt cheap double check you get the right one