Okay, gentlemen (and ladies?) I have a brake problem that has dumbfounded every mechanic that I have taken my car to. First off, it is an 87 325e coupe. A friend of mine gave it to me as a gift, so I don't mind dropping a little bit (I mean a little) of cash into it to make it a daily driver. I'm new to the bimmer business, but I'm experienced in american v-8's and the like. Anyhow lets see if I can explain it well enough, I would appreciate any expertise on the matter.
My friend told me the brakes worked great two weeks ago. He got the car as a parts car for his other one. He drove it about 100 miles and, as I said the brakes were perfect. He took the ABS block out to put on his other car and it didn't work, so he put it back into the said 325e and bled the brakes but couldn't make get any pressure to the rear calipers. I got it, I took all the brke lines loose and blew them out with air and found a few spots where it was stopped up in the back after the rubber hoses into the last metal pieces before the calipers. I blew everything out, connected them back up, and got full air pressure all the way to the rear calipers. I tried bleeding again, got drips at the rear. Took it into the mechanic (firestone) and had them power bleed it, still no luck, same problem. They looked up some kind of infoo and it said "Caution, do not air bleed the ABS box, it could cause damage." So then I figured I messed up the ABS box, so I replaced it, and the ABS computer just in case. Same problem. A BMW mechanic then told me that there was a special way to bleed the rear breaks because of the ABS box, you must depress the brake pedal 12 times before opening the zert fitting. Tried it, doesn't work. Thought it might be the proportional valve, but I was told that either it lets fluid by or it doesn't - but I get fluid to the rear, just no pressure. Any ideas? The front brakes work perfect. All calipers are in good shape. New ABS box, new ABS computer. Brakes were fine before removal and reinstallation of ABS box. Thinking of replacing the booster and master cylinder, but they are working, or the front brakes would be having same problem. Any suggestions? I appreciate it.
My friend told me the brakes worked great two weeks ago. He got the car as a parts car for his other one. He drove it about 100 miles and, as I said the brakes were perfect. He took the ABS block out to put on his other car and it didn't work, so he put it back into the said 325e and bled the brakes but couldn't make get any pressure to the rear calipers. I got it, I took all the brke lines loose and blew them out with air and found a few spots where it was stopped up in the back after the rubber hoses into the last metal pieces before the calipers. I blew everything out, connected them back up, and got full air pressure all the way to the rear calipers. I tried bleeding again, got drips at the rear. Took it into the mechanic (firestone) and had them power bleed it, still no luck, same problem. They looked up some kind of infoo and it said "Caution, do not air bleed the ABS box, it could cause damage." So then I figured I messed up the ABS box, so I replaced it, and the ABS computer just in case. Same problem. A BMW mechanic then told me that there was a special way to bleed the rear breaks because of the ABS box, you must depress the brake pedal 12 times before opening the zert fitting. Tried it, doesn't work. Thought it might be the proportional valve, but I was told that either it lets fluid by or it doesn't - but I get fluid to the rear, just no pressure. Any ideas? The front brakes work perfect. All calipers are in good shape. New ABS box, new ABS computer. Brakes were fine before removal and reinstallation of ABS box. Thinking of replacing the booster and master cylinder, but they are working, or the front brakes would be having same problem. Any suggestions? I appreciate it.