hello,

i have a '93 300E stubborn brake problem that needs some peer review and advice. the history is as follows:

1) replaced REAR brake disks and pads, opened the brake calipers - my mistake! 2) attempted brake bleed using standard pedal pump with that resulted in spotty fluid discharge with apparent air stuck in the lines, 3) thought problem was master cylinder and rebuilt it accordingly, 4) still not able to pedal pump and bleed the brakes, 5) in frustration took the car to a local inde shop and they bled the brakes using shop vacuum bleed tool, 6) since then the brakes have been working fine except about a week later noticed pedal travels about half way down before braking especially during first start up of the day and as car is driven more the pedal pressure/travel acts normally. 7) yesterday i adjusted the parking brake shoes. while there i decided to try and bleed the REAR brakes again thinking there was still air trapped in the lines. this time i used a Mighty Vac tool. initially i started on the right rear wheel and had good fluid flow out of the line but then only air. moved over to the left rear wheel, started bleeding and only spotty burst of fluid and mostly air. the vacuum pressure is good. in fact i can hear gargling air suction coming from the master cylinder fluid reservoir. i find that puzzling how the brake line can be sucking air from a fully topped up reservoir.

i feel something is missing here, i'm doing something wrong, in the bleed procedure. trying to avoid another $100 expense if taking it back to the inde shop. by the way, i have successfully bled the front brakes with good fluid flow - no air.

appreciate your input on this problem!

mark

You have exhausted/emptied the fluid in the reservoir.

Unknowingly to you , the res has TWO containers with a wall between the two..one is for the front brakes and one for the rear..you have to fill the res all the way up for the fluid to go over the seperateing wall into the other container/cavity.

You do not see this other cavity from the outside.

This design is so that you have two brake systems and always have some brake when one side springs a leak..........dual circuit braking..as old as the hills

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A Dalton