W124

I own a W124 1991. Does any one know proper way of bleeding brake system. I have pressurized the master tank to purge air from the bleeder port on the caliper. However, during test drive, after several
times of hard braking, I found that the 4 brakes were dragging. Before that, I have tried bleeding by pumping the bark pedal, but the pedal just stroked without pumping anything.
Hideki
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Brake bleeding is done by two way... One is manual bleeding which needs two people to do the job. The other one is pressurized method in which you attached a device to the master cylinder reservoir with extra brake fluids and pressurizer (there is also a vacuum method).
The first method is most common... One person would sit in the car... pump pedal a couple of times and then hold the pressure... while another person would crack open the bleeder while the inside person continue to press the pedal until it goes down. (Do NOT force pedal all the way down once it stop or otherwise master cylinder is damaged)... while pedal reached the bottom position, the outside guy close the bleeder valve and then inside person repump the pedal. and repeat. It takes a couple of times to get new fluid to come out per caliper. You must make sure you replenish brake fluid and keep cap tight during the process.
The pressurized or vacuum method is one person job. and you just have to make sure there is always plenty of brake fluid available.
Dragging brake is a sign of contamination in brake system which swells up the seals and/or the brake hoses. You either replace the caliper with a rebuilt one or a new one to fix this problem. In this situation, it is possible your brake lines are also damaged. Try bleeding brake again to see if this solves the problem.
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Tiger, perfect instructions. You did, however, omit that the second person should under no circumstances be your wife... :-\
cheers, guenter

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I didn't realize that was a universal problem! I tried having the wife help bleed brakes......ONCE! Steve
wrote:

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LOL... don't have a wife so I wouldn't know!
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Thank you very much for your advice. The master cylinder must be damaged 'cause my wife pumped. I was a second person at that time. I am goint to replace the sealkit in the cylinder.
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