Rock hard brake pedal

[Mustlust]

Just before Xmas I had a prob with the brakes on my 109 tray back. The brakes have recently been overhauled and they worked perfectly for a few months until 2 days before Xmas I went for a drive in the paddock and whoa! First the pedal travelled to the floor, then I pumped it a few times and it went rock hard with not travel at all. The car rolls OK and the brakes aren't binding, it's just that the pedal has next to no travel. I have taken all the drums off and all looks OK. Brakes seem to function OK and car is driveable. When I released a bleed screw the fluid was under quite a bit if pressure, once released the pedal was OK but went hard as soon as it was depressed once more.
Could it be a prob with the master cylinder? and how would I check this out?
Would really appreciate a little advice as this is driving me a little crazy.

[army2a]

hey mate, i had the same issue with my truck. i replaced the whole brake system when i first got my 2a, and had pressure build up in a brandnew master cylinder. the more i used the the brakes the harder the peal got until there was no pedal left! the master cylinder valve was faulty. After replacing the mc the brakes have been fine. you could try pulling the cylinder apart and making sure there is nothing blocking the holes. brakes are a pain in the ###.

[geodon]

Check the pushrod that goes into the back of the master cylinder.

I'm not sure what the Landy system is but the cars I'm used to have had pushrods with adjustable length.

I've had this problem when the pushrod is too long (eg adjustment unwound itself) and then it does not come all the way back home.

One is supposed to set the length so they come all the way back with a tiny bit of end play

[JDNSW]

The most likely cause of the problem is incorrect adjustment of the pushrod on the master cylinder, probably because the locknut came loose and allowed the adjustment to change, although could be something restricting pedal movement. Another possibility is that contaminated brake fluid has caused the seals in the M/C to swell and make the piston stick. Could be as simple as handling the parts with slightly oily hands.

John