Master cylinder.

I've just fitted a new front brake master cylinder and tried to bleed the system but the fluid isn't flowing down the lines. I've tied to get it flowing with bleed valve/s open and closed and with the line disconnected at the reservoir but the fluid level doesn't change at all. Can any one tell me where I'm going wrong or what I haven't done?

Faighaigh.

 

Try pulling some vacuum on the bleeder valve while pumping the handle.

 

Buy a vacumn pump to bleed your brakes. You can pick one up at Autozone....

 

There's probably no Autozone in Spain :mrgreen:

 

oops....hope about a Kragen's then.....lol.....

Just bleed your brakes with a vacuum pump on the bleeder valve & squeezing the brake handle while toppin off with fluid as you go.....makes things a lot easier.......

 

I'm not sure if this is normal but...
I find that if I remove or completely open the bleed screws on the anti-dive, or the calliper if you don't have the anti-dive unit, that after 5 or 10 minutes the brake fluid flows through the whole system, at which point I can close them off and begin a normal bleed process per calliper.
I've done it twice now but in saying that I have not tested this behaviour against another MC.
Give it a shot. Keep the MC reservoir topped up, lid off and do one side at a time and then bleed normally.

 

Still no joy and I don't have a vacuum pump, but someone suggested it might be faulty seals on the pistons?

Faighaigh.

 

Try removing the outlet brake line and putting your finger over the hole. Fill the resovior with fluid and pump it with your finger over the hole. Your finger will act like a check valve and help get the fluid in the master cylinder. At first you will get little squirts of air , just keep going you will eventually get brake fluid through. Do this until the air is out of the master cylinder. Re connect the brake line then continue bleeding. Don't let the resovior go dry or you will have to start over.