Pumping the brakes with Ebrake on or off should not make any difference, the wheel cylinder has to travel to the same point in either case.
worn rear brakes:
If your rear brakes are very worn (think metal to metal) then the wheel cylinder may travel so far that the seal hits a corroded ridge at edge of cylinder and leaks, but usually the piston falls out at the same time and you loose brakes. If your year brakes are way out of adjustment, you may not be able to get a good brake pedal as it takes full master cylinder stroke to move the shoes out to drum so the pedal goes down to floor before there is any brake pressure - symptoms of out of adjustment back brakes: low pedal, ebrake lever comes up all the way, pedal not as low if pushed when ebrake is on. As Wlydman noted, self adjusting VW drums work pretty well. Rear drum shoes that do not comform to drum radius will bend under pressure and give a spongy pedal.
Worn front brakes won't affect pedal, but the level in the front MC resevoir will drop over time as pads wear. (same applies to rear disk)
Brake bleeding:
Air gets into the system 2 ways:
-we let it in when we open up the hydraulics to service them or when
something fails
-the fluid gets low and the MC sucks air. A leaky cylinder will not usually let in air, it just lets out fluid.
(I guess a 3rd source of vapour in the system is if there is water in the system, you will loose brakes when the water gets hot enough to turn to steam)
Getting the air out is actually easy, but there is lots of what I consider miss-information out there, usually around buying/making tools to do the job. Gravity bleeding will do 95% of brake jobs including MC and line replacement. Keep the MC full and cap off, open bleeder and let it drip. When you dont see any bubbles, close bleeder, pump brake pedal to dislodge bubbles, then open bleeder again. Wiggling rubber brake hose will also help dislodge bubbles. Repeat until you get a good solid pedal. The other 5% of the time you need some pressure to push bubbles out, for this you need a helper putting a bit of pressure on pedal while you crack a bleeder, you must close bleeder before pedal is let up. If you want to flush system or you think there is air far upstream, hold a finger loosely on end of bleeder with bleeder cracked open while helper slowly pumps brakes -finger acts like a check valve to stop air from getting in.
Never push pedal to floor with an old MC: crud accumulates at the ends of the bores and you can damage the seals by forcing them into it.
If you are having trouble getting a pedal, use a hose shut off clamp (vice grips will work) to CAREFULLY squish each rubber brake line closed, it wont take much clamping pressure to seal the line. If you still dont have a pedal = air in lines or MC. If you have a nice rock hard pedal, remove clamps one hose at a time until you find the one with air on the other side.
My guess from your description is that you didnt get all the air out on the first bleeding....hope this helps.
*** These procedures have worked for me on hundreds of brake jobs, but lives depend on your brakes, YOU must ensure they are working properly before driving, if you can't be sure, take it to a professional ***
Topic: letting your emergency brake on while bleeding your brakes (Read 17518 times)
