Bench bleeding Master Cylinder?

[dubstar]

I have just got the golf on all fours and taken it for a test drive. When the engine is off, 2 pumps of the brake pedal leads to a solid pedal. With the engine running, the pedal sinks to the floor and I only get 'braking' at the very end of the pedal movement.

This probably shows I have air in the master cylinder still........

I am using my power bleeder and, on my 2 previous master cylinder changes, I never had to bench bleed the m/cyl. Any tricks to getting air out while in the car?

I have heard you can pressurise the system with the power bleeder, crack open a nipple and then depress the pedal a couple of times.......

For those, who haven't read my build thread, I have new brakes all round and a new booster/master.

[Brisben]

I have just got the golf on all fours and taken it for a test drive. When the engine is off, 2 pumps of the brake pedal leads to a solid pedal. With the engine running, the pedal sinks to the floor and I only get 'braking' at the very end of the pedal movement.

This probably shows I have air in the master cylinder still........

I am using my power bleeder and, on my 2 previous master cylinder changes, I never had to bench bleed the m/cyl. Any tricks to getting air out while in the car?

I have heard you can pressurise the system with the power bleeder, crack open a nipple and then depress the pedal a couple of times.......

For those, who haven't read my build thread, I have new brakes all round and a new booster/master.

I haven't read your build, but the brake booster vacuum would be my first bet.

[dubstar]

I would have thought that, as the pedal becomes easier to push with the car running, the booster would be fine? Am I wrong in that assumption?

[Peter Jones]

Sometimes the old ways are the best. Get a friend to pump and hold the pedal while you bleed at the brakes. I've found the power bleeder can't always force the air out of a system.