Trouble Bleeding Brakes

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bimmerjoe
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Trouble Bleeding Brakes

Post by bimmerjoe »

Just replaced the 2 front calipers on the 82 633csi I have been working on. Have had trouble bleeding the brakes. I have a steady stream of fluid from the right side, top bleeder, but no matter how long I have my wife pumping the brake, I cant get any fluid out of the 2 lower bleeders. Could it be just that I have too much air in the lines and I just need to keep going? I have similar calipers on my '70 1600 and have changed calipers, hoses, and lines and have never experienced this. Any ideas?

Thanks,

Joe
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hornhospital
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Re: Trouble Bleeding Brakes

Post by hornhospital »

Are you sure the lower bleeders are actually open? I don't mean turned ccw to open, but the passageway may be blocked, either in the bleed screw or within the caliper body.
Ken Kanne
'84 633CSi "Sylvia"; '85 635CSi "Katja";'85 325e "Hazel Ann"; '95 M3 "Ashlyn"
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olympia57
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Re: Trouble Bleeding Brakes

Post by olympia57 »

/\ /\ /\ Plus one on the possible blocked bleed nipples .
When I rebuild my calipers I found a surprising amount of crud in the galleries when they were blown out .Several nipples were blocked too.
Is this a four piston caliper ,early twin pipe system ?
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1981 635 series 1
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bimmerjoe
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Re: Trouble Bleeding Brakes

Post by bimmerjoe »

Yes, it is the 4 piston twin line setup. I will check the bleeder screws and see if that is the culprit. Thanks for the info and I will keep you posted on my progress.
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bimmerjoe
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Re: Trouble Bleeding Brakes

Post by bimmerjoe »

So, I checked the bleeders, clear, checked the steel lines from the hoses to the caliper, clear. Tried the tool that sucks the brake fluid through the lines; no luck. Traced the offending line back to the master cylinder & unhooked, while pushing the brake pedal in with the line off the MC, no fluid came out of the hole, reservoir was full and not emptying out as the pedal was depressed several times. A buddy who was helping me said he thought it could be the MC. I plan on changing the rubber hose on that line as well. Any suggestions? Should I be looking to change the MC or should I be looking at somethin else? Thank again for the help!

Joe
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olympia57
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Re: Trouble Bleeding Brakes

Post by olympia57 »

I was waiting to see how you got on.....

If you have no fluid being pumped from any of the ports on the MC when the reservoir is still connected ,then it's at fault.
I had a problem when bleeding my brakes in that I couldn't expel all the air in the system after a complete rebuild and after it nearly drove me suicidal I rebuilt the MC and that ( eventually ) fixed the problem.
New MC's are very expensive but they are easily removed and dismantled . I'd do that and if the bore is unscored rebuild it with an easily available kit.
I bought a couple at circa £10 each ( $12.5 ) , here's a German supplier ,
http://www.ebay.co.uk/itm/Brake-Master- ... SwCypWmK6A
Check that your MC ID is the same as mine at 22.2 mm (Ate ) because there are several diameters . Use your VIN on Real OEM and it will confirm or otherwise.
If you can afford to I'd renew the flexibles when the system is dismantled because be warned that once disrupted the early twin pipe / servo system can be a real PITA to bleed . I use a pressure bleeder and even then had to go round the car many times to get it right .
Good luck
Don
1981 635 series 1
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bimmerjoe
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Re: Trouble Bleeding Brakes

Post by bimmerjoe »

Thanks for the info Don! I think I am going to buy a new MC, my mechanical abilities are questionable at best so it would probably be better for me to just have to worry about changing the MC and not getting into the rebuild. I also plan on changing all 4 front flex hoses. I have quite a bit of experience in this area with my 1600. Had to pretty much replace all of the hoses, lines, calipers from the MC out to the front wheels. This system for the 633 reminds me a lot of the setup on my 1600. I went round and round changing things like the caliper, then a hose, then another hose, then a line, Took me a while to get it sorted out but when I did it was night & day. I guess that's where I am with the 633 now so I am just going to go ahead & do the lines & hoses as well as the MC. Thanks again for the help. I really appreciate it!

Cheers,

Joe
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