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MG MGB Technical - M/C Bench Bleed

Replacing the brake master cylinder on my 1979 MGB. Poured fresh brake fluid into the reservoir and attemped to bench bleed the new cylinder prior to mounting it to the servo assy. I have not been able to get the cylinder to bleed. What am I doing wrong??

Cheers

Gary
gary hansen

Not that I've ever done it on either brake or clutch master replacements as it just seems too messy and pointless (other than to check the new master actually works!) but how are you doing it? The only way that makes any sense at all to me is where a pipe is run from the outlet (two for twin masters) and angled back into the reservoir through the filler hole to go below the fluid level. Successive pumps with this arrangement should expel all the air in the pipes as well as the cylinder. If the outlet pipe is open to atmosphere it will keep sucking in air on the back stroke of the piston.
Paul Hunt

OK. Left the M/C sit overnight with fluid in the reservoir. The fluid found its way through the cylinder. So I was able to mount the M/C to the vacuum booster servo and reconnect the lines. All seems to be working fine. I will check on the reservoir level tomorrow to ensure it remains full.

Thanx Paul for the respond

cheers

Gary
gary hansen

Having bench bled countless brake MCs I can easily describe how I did it. First you need nippled fittings that fit the MC outlet hole/holes then you need hose/hoses that fit tightly on the nipples and run up to the resovoirs. With the MC mounted in a vice, pump the MC until the bubbles stop. Leave the hoses attached
while you mount the MC,remove the fittings one at a time and quickly fit the brake lines.
Depending on the design of the MC this could save a lot of time or a little time. Ric
RIC LLOYD

RIC, Checked the M/C this AM and all seems well. Fluid is still at the top, pedal is still up. Will bleed entire system when a friend stops by over the w/e to lend a hand

Thanx for response

cheers

Gary
gary hansen

This thread was discussed between 16/11/2009 and 18/11/2009

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