no brakes

[steve_k]

as the title.

i was going to be taking my sport for it's first mot in 8yr's (!!) onlt to find when i backed off the drive that the brakes weren't working properly.

a bit of history about the brakes on my e30
front brakes are hi spec billet 4 calipers (4x42mm pistons) with 285x25mm discs, ferrodo ds3000 pads.
abs was removed about 10yrs ago due to it failing, brakes worked fine after it was removed.

rear brakes are 37mm single piston calipers from a 325i tourer,
e90 25.5mm MC & servo,
full braided steel lines with T piece for the front brakes,

one piece braided steel lines from the MC to each front caliper,

full braided steel lines to the adjustable bias valve (wilwood screw type) then one piece line to the rear T piece above the diff (it's a stainless steel AN fitting) then full one piece braided line to each caliper,

all four calipers have a set of stainless steel "speed bleeders" which are seated correctly.

i've bled the brakes several times using a pressure bleeder & someone else pressing the pedal.

each time i've done that i've tested them on the private road estate behind my house & they've worked fine.

came to take the car for mot this morning only to fine there's nothing there when i press the brake pedal, it's sinks to the floor.

going to get the car in the air again this morning & make sure there aint any leaks along the brakes lines or at the calipers.

anyone have any ideas on what could have caused this?

[steve_k]

forgot to add, when the engine is off the pedal is firm & only moves a few mm.

[steve_k]

well i've got the car in the air,

i've checked all the unions from the MC to all four calipers, no signs of any leaks, all look dry even after pumping the pedal quite a few times,

checked all along the lines & there's no kinks or twists, the reservoir is still at the max line,

makes no sense to me at all.

[flybynite]

makes no sense to me at all.

Sounds like a buggered Master Cylinder to me. 8 yrs standing not out of the bounds of possibility especially.

[steve_k]

makes no sense to me at all.

Sounds like a buggered Master Cylinder to me. 8 yrs standing not out of the bounds of possibility especially.

the MC was a refurbed one from an e90 which i fitted a couple of months ago.

[flybynite]

the MC was a refurbed one from an e90 which i fitted a couple of months ago.

Who 'refubed' it?, sounds even more like the reason to me.

[BenHar]

If the pedal is hard with the engine off but sinks to the floor with it running I would suspect something wrong with the servo.

Ben

[steve_k]

the MC was a refurbed one from an e90 which i fitted a couple of months ago.

Who 'refubed' it?, sounds even more like the reason to me.

i got it off a mate of mine who rebuilt it (new piston, seals, etc) as he was going to use it on his till he sold the car.

[steve_k]

If the pedal is hard with the engine off but sinks to the floor with it running I would suspect something wrong with the servo.

Ben

does seem starnge but that happens on my daily (mk5 jetta), pedal is hard till the engines running then works as normal, just seems strange how it's happened on the e30.

[steve_k]

well tomorrow i'm going to flush the whole system out, check the one wat valve on the servo (brand new), check all the lines & unions again & then bleed it all again but get my dad to pump the pedal & do it the old fashioned way.