Thread: Defender Brake Problem

Booster.

Your vacuum pump may have failed, or you may have a split in the pipe from that to the diaphragm, or the diaphragm itself may have a split.

not weird if the booster is b******d

- Check above to see if you have vacuum TO the booster... then if the booster is holding the vacuum...

if its a petrol engine.....its probably the booster......

if its diesel.....it may also the vacuum pump on the back of the alternator.....


can you hear any hissing when the engine is running.....?
either inside the car or under the bonnet at the brake booster......?

Originally Posted by GyroLandy

I haev a '94 defender with discs front and rear. Out of the blue the brake pedal has become very hard and don't have a lot of travel and braking is very poor. I have started at the drivers side and bled all 4 wheels going anti-clockwise. Not a lot of air came out so not sure what the problem could be. Pads and disc still quite new.

Where else can the problem lie? Master cylinder? Perhaps the booster? With or without the engine running the brakes feel the same which is weird.

Thx

As above, Booster or Vacuum Pump.
Bleed from the furthest caliper from the Master cylinder first, i.e. P/R, D/R, P/F, D/F, Regards Frank.

Just to add a little more info on the booster. They are prone to cracking around change in profile where the master cylinder bolts on. Have someone hop in the car and press the brake pedal. Makes the cracks easier to see.

Steve

Yes likely to be cracked booster on the early non Td5 defenders, also to check vac pump output remove hose from booster with engine running and you should get at least 15 to 20 in/Hg vacuum without any noticeable 'chuff chuff' pulses, a good 300Tdi vac pump will be relatively smooth in its suction. If pulsing a lot it usually means a valve failure internally.
The vac lines can and do wear through near where they run out from the pump and under the airfilter bracket on the defender, so check that too.
Also, after switching engine off, there should still be vacuum inside the booster chamber for hours afterwards, or the booster or one way valve in the line is faulty.

JC

I say vacum pump,

Find TDC, remove the pump, drill out existing rivets and remove pump cover, overhaul and replace rivets with stainless fasteners, repair the seal or completely replace entire unit.

Should only take about three hours including smoko!

I had the same issue with the 130 about 6 months ago.

All fixed now with new brake pads, good as new!

Thanks to some very helpful threads.