Brake disc replacement!!! GGrrrrr

Hi folks,


PADS NOT DISCS!!!!

bit of a problem! I have replaced my front pads tonight and have a problem!!! Went in no problem, calipers went back with some effort fine, plenty of fluid in the reservoir BUT pumping and pumping to pedal and I have NO BRAKES at all.

What have I/am I doing wrong?

Sorry to sound such a doughnut, i've replaced them before and they just pumped straight up tight. What could it be!!!????

My neighbour said I might have reversed the seal on the master cylinder. Is that possible and likely? How would I check?

it is entirely possible. i believe it happens when the piston is pushed back too fast. the only way i know of checking/ sorting it is to strip the master.

My neighbour has suggested I do a bleed anyway and see if that sorts it.

This is why I always open the bleed nipple on the caliper when pushing the pistons back.

A pressure bleed may help, but stripping the master cylinder to sort out the seal isn't difficult.

yer could well of done the master cylinder

tbh mate if you got nothing on the brakes the master probably a good place to start. you could try eazi bleed but if you have NOTHIN AT ALL then its not gunna be on the caliper even with a little air in the system the brakes will work after a couple of pumps.

andyb66 said:

This is why I always open the bleed nipple on the caliper when pushing the pistons back.

A pressure bleed may help, but stripping the master cylinder to sort out the seal isn't difficult.

Click to expand...

good advice!!!!!!!!!!!!!! forgot to mention that...

Is it likely that the seal can be replaced/repositioned? I have looked in the Haynes manual, I am thinking for 45 quid a new master cylinder might be easier!!!

I'd rather pop a seal in the workshop than on the road. If you disrupted a seal on the MC pushing the caliper back, the MC is overdue a change. They will flip due to the seal going stiff or the cylinder having corrosion on it.

Ok folks......the dilemma continues.

I have just tried to bleed the brakes and all I get is a little oil/air into the pipe on the push and it returns on the lift. Tried a one way valve and "old style" bleeding.

Does this sympton suggest Master cylinder is more likely??

please explain how you are doing the bleeding. is it your technique?

Using a one way valve on a tube, open nipple, pump brakes.

I then tried JUST tubing, open nipple push brakes, close nipple, release peddle, open nipple, push peddle, close nipple......and so on.

Both offered the same result.

Its as though something isn't allowing any pressure to be built up if you know what I mean!

Are all the brake lines completely tightened? Plenty of brake fluid in the reservoir? No kinked (solid) brake lines?

If so, then the only thing it could be is the master cylinder, since the fluid goes directly into it by gravity then is held in with the master cylinder's seals.

Thanks for the advice.

The reservoir is full to full, all lines are as they were before I did pads.

I reckon I pushed them back way too quickly and with the force of ten elephants!!!

I'll order as new MC in the morning. Local one for £55 sound about right for a '96 300tdi?