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Dead Clutch Pedal After New MC, SC, Hoses, & Vacuum Bleed

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    Dead Clutch Pedal After New MC, SC, Hoses, & Vacuum Bleed

    Hi All,

    As the title indicates - clutch is completely dead after a master cylinder and slave cylinder swap. I also changed the hose between brake master cylinder and clutch master cylinder as well as gone the steel-braided clutch line route from the clutch mc to the clutch sc.

    I'll try to post a video of what's happening exactly but just in case I can't - If I touch the pedal with my index finger it falls straight to the stopper and if I touch the back of the pedal is springs right back up on its own. There is zero stiffness to the pedal.

    I have vacuum bled the piss out of this thing, probably passed a whole bottle through the reservoir and out of the slave cylinder. As soon as I kick on the vacuum I crack the bleeder and out comes zero bubble, clean, new brake fluid. Reservoir goes from max to low every time I do this and I've kept it full.

    Also dismantled the slave cylinder and, when I depress the clutch sc plunger/rod and hold it depressed while pumping the pedal, the clutch sc plunger/rod fights against my palm, rising about 1/4" with every pump of the clutch pedal. I should note that it's difficult to depress the rod after the bleed. It was easy to do before I installed the unit and bled the system.

    Didn't take any close up looks at it but I did peek and I do see the fork through clutch sc hole. It's still there. Clutch was fully operational but the old sc had a broken seal and I wanted to swap the rubber lines out so I figured why not go all new and refresh the clutch. Clutch MC is FTE and Clutch SC is Febi, both OEM.

    I have pumped the pedal about three thousand times! I've also double checked all steel line fitting connections and they are nice and seated. I have been told to reverse bleed it as opposed to vacuum bleed it but sounds like overkill. I also don't want to spend 200 bucks on a decent reverse bleeder.

    All the DIY videos and threads don't mention having to go that route. Very simple system and I am stumped so that makes me a bonafide idiot! Any advice or direction would be greatly appreciated!!
    Last edited by E30Bastard; 05-24-2019, 10:12 AM.
    "It wouldn't be there if it wasn't..." - Milton Berle

    1988 325iS - M20

    #2
    Gosh, was like 10kb too large. Here's a youtube link:

    https://youtu.be/nbmxPelO71k

    Sent from my Pixel 2 XL using Tapatalk
    "It wouldn't be there if it wasn't..." - Milton Berle

    1988 325iS - M20

    Comment


      #3
      So it looks like you have covered most of the basics on bleeding. I had a similar issue with a GM clutch years back. I was about to give up. And the clutch finally built up pressure. Don't give up.

      Do you by any chance tried pinching off the line and see if the pedal gets any feed back? I am wondering if its a bad slave or master cyl? Got the old parts still? Maybe swap in one that is good (assuming they are good) and see if that makes a difference?

      Comment


        #4
        I threw them out and garbage day was this morning for me BUT the master cylinder would depress and not pop back up and the slave cylinder seals were busted so that's why they immediately hit the trash bin.

        Funny how my clutch worked with two old, broken parts..[emoji23]

        Just arrived home from work. I guess I will try more bleeding and pumping. I studied the clutch and pedal diagrams from realoem today and am only further mystified by the simplicity of it all.

        Sent from my Pixel 2 XL using Tapatalk
        "It wouldn't be there if it wasn't..." - Milton Berle

        1988 325iS - M20

        Comment


          #5
          Dead Clutch Pedal After New MC, SC, Hoses, & Vacuum Bleed

          Ive found the e30 clutch to be an easy one to pressure bleed. The motive pressure bleeder, used with air only on fluid, makes quick work. I apply approx 10-15 psi on the motive, open bleed screw, tap parts to dislodge bubble, close screw. Pump clutch. Repeat. I do not do the two man pump/open/close.

          I replaced a master and dont recall bench bleeding it but it is usually the right thing to do.


          Sent from my iPhone using Tapatalk

          Comment


            #6
            Remove the slave cylinder and depress the pin of the slave (using the bell housing as leverage) about 20 times or until it starts to have build some pressure. If there is any air inside there, it will all be pushed to the top.

            If that doesn't work, your new master or slave cylinder likely has an internal leak. Just went through this with a brand new Febi unit a couple weeks ago.
            Autobahn Motorsport - Portland, Oregon
            @autobahnmotorsport
            '88 M5 | '88 325i | '88 325is | '88 330is | '91 325is | '91 M-Technic 325ic | '93 740il | '03 325it

            Comment


              #7
              Originally posted by r-mm View Post
              Ive found the e30 clutch to be an easy one to pressure bleed. The motive pressure bleeder, used with air only on fluid, makes quick work. I apply approx 10-15 psi on the motive, open bleed screw, tap parts to dislodge bubble, close screw. Pump clutch. Repeat. I do not do the two man pump/open/close.

              I replaced a master and dont recall bench bleeding it but it is usually the right thing to do.


              Sent from my iPhone using Tapatalk
              Appreciate all the feedback, Guys. As for the solution -

              I was able to get it to be satisfactory with a combo of vacuum and two man method of pump and bleed but r-mm is most definitely correct. Forked out some cash and bought myself a pressure bleeder. It took about five minutes with some pulse bleeding, a few full shots of brake fluid, and about 30 seconds of gravity bleeding to burp it. Closed up the bleed screw and the clutch was rock solid, no pumping needed.

              I bought the Phoenix reverse bleeder but anything of the same principle will do. Nice tool to have in the garage, too!
              "It wouldn't be there if it wasn't..." - Milton Berle

              1988 325iS - M20

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