Brake bleeding problem

Ok, have just replaced my brake lines with a set of braided ones and I'm having a problem bleeding them. Everything went together fine, no problems at all, but then I can't bleed them.

I'm going for the old fashioned, few pumps on the brake lever, hold lever in, undo bleed nipple, wait a second, tighten bleed nipple, release brake lever, repeat. It's worked fine in the past.

I'm getting plenty of fluid through when I undo the bleed nipple, and as far as I can tell it seems to be bubble free, but I'm not getting anything more than minor pressure on the brake lever. I have tied it back and will leave it overnight to see if that helps, but I don't know if it will.

The only thing I could see that might be a problem (I haven't got a clue) is a tiny split in the part circled in the image below:



It's the rubber membrane that the brake lever presses on, no idea if a split in that would prevent the brakes from being bled or not. If it would, can anybody give me the part number for a replacement, I've had a brief look on google but can't find it.

Thanks.

have you changed the levers too?? if so refit OEM ones to bleed them. they have a longer stroke to pump fluid into the system. hope this helps.

Should have said, not my picture. Still have the OEM brake lever on mine.

Not meaning to sound pushy, but I really need to get this fixed tomorrow so would appreciate any help anybody can give, mainly whether a small split in the part that I've pointed out would cause a problem in bleeding the brakes, and if it would then what the hell the part is so I can buy a new one!

[Paul the 6th]

have you checked all round the calipers, brake lines, master cylinder etc. for any leaking brake fluid?

As far as I could tell there was nothing leaking from anywhere, although when I tied the lever back I dried everything and will check it in about 2 hours to make sure it's still dry.

[DJ123]

Your location would be handy, incase anyone is local to give a hand.

If you have the standard levers on, what number is the dial set to? Set it to number 1, it is the furthest 'out' position for the lever. See if this makes a difference when bleeding the brakes.
have you got the cap off the master cylinder and the diaphragm out? is there plenty of fluid in the master cylinder?

Have you tried bleeding the brakes with the top off the MC? This will make fluid squirt all over the shop but encourages any air in the top half of the lines to travel upwards. As air stuck in the lines can compress enough to give slight pressure on the lever but not get pushed through to the bleed nipple on the calliper.

have you tried reverse bleeding. remove res cap, then use a fluid filled syringe and feed it in through the bleed nipple, with the use of a hose, pushing air out as it rises through the system.

I always bleed my brakes with the cap off the MC and the diaphragm out, making sure to keep the fluid well topped up, will give reverse bleeding it a go see if that helps.

Still nobody got an idea what the part that is damaged is?