Discovery brakes

Hi all ever since I've owned my 97 discovery tdi its had pretty sad breaking performance i push the brake hard and it just takes longer than it should to stop. Eventually i got around to bleeding the brakes not much better after that bleeding them again still no luck so I just replaced the master cylinder and bleeding them again still no big difference. The weird thing is when I push the brakes the first time they have pretty good stopping force but if I push the pedal again straight afterwards the brakes are as useless as before. Any suggestions? Buggered vacuum pump/ vacuum leak? Maybe glazed up brake pads. Any help would be greatly appreciated.

Also when I push it the second time the pedal doesn't go as far goes hard but poor stopping performance.

That all points to poor vacuum, so could be pump or a vacuum leak somewhere including the
Possibility of the servo itself leaking,

A + for the vacuum issue.
I had similar issues, and found the one way valve was sticking, thats the valve at the end of vac hose where it enters the servo, (2 valves one at each end of the vac hose on a petrol engine).
So just just pull the valve out from the grommet after undoing the clip and removing the hose, and clean the valve or replace the valve as they can ware out I believe, also if the grommet looks a bit iffy replace that as well.

Iirc the tdi discos had a small pipe that Teed off the main servo vac pipe, this pipe was soft rubber and would perish then fall off and you would have a vac leak and poor brakes.
Again from memory it is in the engine bay and on the firewall?

Yes this small rubber pipe went through the firewall to the heater unit, it operated the valve to block fresh air
Coming into the cabin, definitely worth checking,

Just checked a few pipes around there and I had 3 leaks in the cruise control lines and 1 in the main hose from pump to servo will se what happens when I drive home tonight from work probably may as well put the smoke machine on to. Right on that small plastic t piece.

Tunatime123 said:

Just checked a few pipes around there and I had 3 leaks in the cruise control lines and 1 in the main hose from pump to servo will se what happens when I drive home tonight from work probably may as well put the smoke machine on to. Right on that small plastic t piece.

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Just use both feet on the middle pedal!!!