Can't bleed disc brake and starting to get suicidal !

[10 inch Terror]

Ok i'm trying to bleed a disc brake and i'm not getting anywhere. I can get fluid to squirt out of the bleed nipple but can't get the brake to work. Set up is Yamaha master with Nissin caliper and new Chiggy quality hose and fittings. Please help. Cheers Pete

[wack 63]

I think half the problem is the pistons are stuck in the caliper and just need a bit of pressure to get them moving.I have a pump oil can (with brake fluid)with a piece of pipe jubilee clipped on which I fit on the loosened bleed nipple and force fluid into the caliper to get the pistons moving or I use an air line.You can also reverse bleed the system this way(watch out for overflow) then bleed normally with fresh fluid. If it's an old caliper it may need a strip.

[ForemanBob]

I use a large syringe that you can put on the bleed nipple and vacuum out any air bubbles left trapped....

With the use of a fine needle you can also inject additional fluid through the small holes in the master cylinder to pressurise the system more...

I was at my wits end for days until I got this lot sorted from a friend who works in the NHS...

Worked a treat and got me sorted in 30mins after that

[cezeta]

if you take the lever off and pump the master piston in and out with the blunt ond of a pencil or a piece of dowel then you will get the bubbles to be pushed down rather than the fluid tricling past the air lock.

also tap the hose and pump the master and you will see the bubbles come to the top too and vent out into the master.

i learned this from a motorcycle mechanic after two hours of similar misery.

[paul213]

try pumping up the master cylinder to get pressure hold in the lever and release the bleed nipple then lock the nipple and repeat . sometimes doing it the normal way doesn't shift the air fast enough and it just drifts back to where it was

[10 inch Terror]

All sorted now. I had the master cylinder painted during the re-build and i can only think it got damaged in some way as i changed it for one i knew worked and the brake works a treat now. Thanks for any tips or advice given. Pete