Bleeding the Brakes
This component is part of Brake System.
Brake Bleeding Tools
http://www.bmw-m.net/TechProc/bleeder.htm
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Would like to bleed my brakes and wanted to know if the brake booster has one or more bleed nipples. Also, can anyone explain the order in which I should bleed each brake cylinder?
I bleed my brakes starting with the farthest wheel cylinder from the master cylinder, which is the passenger side rear brake. Since I don't own an "Easy Bleed" system I have my wife pump while I open and close the bleed screw. The trick is to continually top up the reservoir so air does not get into the system. I use only Castrol brake fluid which is available in larger size containers. The first cylinder takes the longest to do, but you'll see all kinds of dark crud come through. It's a wonderful thing to watch. Get a clear plastic hose from the hardware store just large enough to fit snuggly over the bleed screw and put the other end in a large jar to collect the old fluid. After the first cylinder runs completely clear, move to the driver's side rear, then the passenger side front, and finally the driver's side front.
Pete Lesler: Start at the furthest brake from the master cylinder and work towards the brake cylinder. i.e. first the right rear, then the left rear, then the right front, then the left front. Do the clutch slave as well. I use a system that pressurizes the system with tire air pressure, so it becomes a one man job. No pumping is necessary. I usually go over the sequence three times untill I see no more bubbles and the pedal is very firm.
The MB factory manual that I have actually mentions that one should even flush the system with methylated spirits at regular intervals. (I forgot what intervals but it is part of some service routine). They insist using this alcohol and nothing else because it dissolves brake fluid but does not affect any rubber parts and hoses. I have done this on all my vehicles and it was as simple as draining the brake fluid by opening a bleed screw and pumping it out. Then I filled the reservoir with methylated sprits and pumped it through and bled it through all the bleed screws. I kept doing this till the spirits comes out clean. You won’t believe all the black crumbs and bits that come out sometimes. I then reverse the process, drain the spirits and fill up with new fluid. I pump that through till the fluid comes out and no more spirits. The rest is a matter of bleeding the system.
Brake fluid may not be good enough to clean off the dirt on the calipers. You can clean the calipers with any strong cleaner and even gasoline if the dirt is very stubborn. Just don't soak it in the stuff because there is a internal rubber ring that connects the 2 caliper halves together. We do not want that to swell up. Flush it off properly and then remove the residues with something like Benzine, thinners or spirits. The objective is to get the parts clean of dirt and then clean of any solvent or fat residue that might react with any rubber parts and swell or deteriorate.
I just replaced my master cylinder, front calipers, rotors, rear wheel cylinders, pads, ect. The master cylinder was the last thing I replaced. I purchased an eez-bleed pressure bleeding system and bled the brakes 3 times (RR, LR, RF, LF) X 3, fluid ran nice and clear, no bubbles, but still can't get any pedal (it goes right to the floor). Brake booster is working, I've also replaced the flexible brake lines. What the heck is going on? It is kind of annoying trying to drive the car using only the hand brake... Do I have to tilt the car funny (like jack up the ass end), bleed the master cylinder, maybe just set fire to the car. I've spent two days crawling around under the car trying to get the brakes working. I'm considering Sepuku (Hara Kiri) at this point. Please send help.
Bernt Damm: have you tried the old fashioned way of pumping the pedal while bleeding? Does fluid come out the bleeders nicely when you push the pedal down? Did you replace the brake hoses? They swell closed with age and vacuum bleed wont pull fluid through them very well if at all. If you can't pump any fluid with the pedal on front and rear wheels, then you probably have a faulty or incorrect master cylinder. It might not be in contact with the pin in the booster. It may even be stuck. Remove it again and pump the rear end with a screwdriver to see that it does pump fluid through. Mind any paint in the vicinity!! You should be able to hear it working when pumping.
All of the brake hoses are new. I got the new Master Cylinder from Star Quality and it matched exactly with the old one. I hope to get someone to help me pump the brakes this weekend, and I can check to see if the MC is pumping fluid. I'm pretty tired of being covered in brake fluid. I didn't pre-bleed the master cylinder unfortunately.
Bernt again: No reason to be covered in brake fluid. I is normally quite clean process. Assuming all hoses and stuff are new: If the pedal does actually push the cylinder and no fluid is pumped through, then it is the master cylinder that is either stuck or faulty. My guess is stuck. I had that once. Else, the easy bleed didn't do the job and you simply have to bleed the system properly. This does not take more than about 2-3 minutes per wheel without the eazibleed thingy but you need a wife/friend or someone to push down the brake while the bleed is open and then to release it while the bleed it closed. you need a clear PVC hose to fit the nipple and an bottle to catch the fluid.
The only two things I can think of are the master cylinder seals are dried out and allowing the fluid to seep forth, or the push pin inside the booster is not inserted into the actuator rod for the master cylinder. Two questions: engine off have someone push the pedal while you listen to the booster/ master cylinder(listen for scraping sounds or squishing sounds). Either one will tell you need to seperate the master cylinder from the booster. Also observe the lever arm connected between the booster holding assembly and the firewall-does this lever move when someone pumps the pedal? Could have slipped off or has broken. Hope this helps and no need to do a seppuku, as it's not your failure.
I agree with Bernt, bleed the brakes properly with an assistant to pump the pedal for you. EZ-bleed systems allow air to be sucked back into the lines past the bleed nipple threads.
I use this routine, with my well-trained wife in the drivers seat: open the bleed nipple, and say "down". Wife depresses pedal and holds it down, she says "down" at that point. Close the nipple, not too tight but enough to seal. You then say "up", wife allows pedal up, when it's up she says "up, one". Repeat, but this time at the end she says "up, two", thereby counting the number of pedal strokes. At five I check the reservoir, again at 10, 15 etc until more fluid is needed.
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