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Air or Blown Cylinders?

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    Air or Blown Cylinders?

    So, two days ago I was getting a soft pedal while I was driving; I was like "WTH?!" so I pumped my clutch pedal while driving out of panic, and it got hard again. I was cruising in 5th at around 80MPH heading home, when the exact same thing happened again when I got off my offramp; pumped it again about 20 times before it got hard again at the traffic light. Barely got it home;

    Yesterday, I was getting grinding in my gears; I know it's not the transmission or the oil because I just put in new fluid and my swap is fairly new. Would only grind during hard shifts into 2nd/3rd, but it only happens when my clutch is soft; if my pedal is hard, no grinding. So I thought it might have just been my brake reservoir being low on fluid. so I looked inside my res and saw brown fluid. I didnt think much of it and topped it off.

    Today, I got in the car and same thing; soft clutch, but goes away after I pump it. I was driving on th me freeway to my class when the clutch pedal lost all pressure and the engine bogged at the same time. It took an abnormally long time of pumping to get pressure back in again, and it seemed like my brake pedal was getting way kore pressure than it should have.

    I was thinking it's either air in my system; because once there is pressure, it's fine until it just sits (like if I'm cruising or the car is parked). Either that, or it's a blown CMS/CSS because I'm losing pressure. However, there are no leaks and all my lines are dry and new from recently being replaced because of my 5-speed swap.

    The only thing I would think is that my CMS gets blown maybe because I don't have the giant clutch spring behind my clutch? There are two springs and I only have the smaller one connected as I only attached my clutch pedal to my automatic pedal box and the auto box doesn't have the bracket to connect the large spring. Would the lack of backpressure cause my CMS to blow?

    Also, when I pump my clutch while it's parked, I kinda hear a pop when it's fully pressed. I'm pretty sure this is from my CSS, as it is coming from outside/under the car.

    Officially confused about this is the first time I've ever encountered this, besides blowing the plastic nipple on my CMS before.

    #2
    My brother had a similar problem with his e30. Ended up being the slave cylinder leaking. Pop it out and check to see if your losing fluid down there
    sigpic

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      #3
      Well.. I've been running like this for three days now because I havent had time to fix it; if I was losing fluid, wouldn't I have noticed by now? The reservoir is at the same level I filled it at yesterday... I'm going to bleed it tonight and see if anything changes.

      I'll replace my CMS and CSS tomorrow; it's like $50 for the pair at Autozone and I have a lifetime warranty on my CSS which means I'll pretty much get a new one free

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        #4
        That sounds most like a bad clutch master cylinder.
        The car makes it possible, but the driver makes it happen.
        Jim Levie, Huntsville, AL

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          #5
          Originally posted by jlevie View Post
          That sounds most like a bad clutch master cylinder.
          +1. Id swap the master and slave and they can leak internally.
          Seat Shocks....I have passed the baton to John Christy from Ninestitch. Email John or Garrett at ninestitch1@gmail.com

          https://www.r3vlimited.com/board/sho...86#post4944786
          Alice the Time Capsule
          http://www.r3vlimited.com/board/showthread.php?t=360504
          87 Zinno Cabrio barn find 98k and still smells like a barn. Build thread http://www.r3vlimited.com/board/show...20#post3455220

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            #6
            Hmm.. Do you think the lack of backpressure from not having the large spring on my pedal box is the cause of it? This has happened before with my CMS, but that was because the plastic nipple broke and was leaking from that.

            Leaking internally however? I'm not quite sure what you mean by that

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              #7
              Master would be my best guess. Had a similar problem and that was the cause. Possibly the slave but I doubt it.

              The Build:
              http://www.r3vlimited.com/board/showthread.php?t=191125

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                #8
                Okay, now that we've established my Master Cylinder is the probable cause, does anyone know the answer to the question stated before?

                This will be the second master cylinder I've blown in the passed 2 months, so I'd really like to know. Essentially, I'm assuming that's what's blowing my cylinders, so I'll probably replace it regardless, but I would just like to know and hear it from the horses mouth.

                Thanks to everyone who've replied so far

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                  #9
                  It's such a fine line between a horse's mouth and its a@@...lol..but here goes...

                  I cant think of anything that could cause a master to "blow" other than normal wear & tear or a mfg defect (which happens often with all kinds of parts). Depending on where you bought the last one, I'd make a warranty claim & replace the slave as well for good measure.

                  All of this assumes your pivot parts are as they should be.

                  Just my 2c...well actually my horse's :)
                  Seat Shocks....I have passed the baton to John Christy from Ninestitch. Email John or Garrett at ninestitch1@gmail.com

                  https://www.r3vlimited.com/board/sho...86#post4944786
                  Alice the Time Capsule
                  http://www.r3vlimited.com/board/showthread.php?t=360504
                  87 Zinno Cabrio barn find 98k and still smells like a barn. Build thread http://www.r3vlimited.com/board/show...20#post3455220

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                    #10
                    Were the replacement master cylinders BMW parts or generic? If the latter, the quality is suspect.
                    The car makes it possible, but the driver makes it happen.
                    Jim Levie, Huntsville, AL

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                      #11
                      Well, they are both OEM parts; both clutch master cylinders I had were. That rules out the quality issue.

                      However; the trend is evident. When I replaced the first one, it was a month after my 5-speed swap. That's when I got my new CMC; a month later, I blow another one. Obviously there's something wrong with my current setup

                      I highly suspect the lack of backpressure in my system from lack of clutch springs since my pivots are perfectly aligned and my system is correctly bled. That rules out any other possiblity really because that is the only thing I do not have to BMW specs on my current setup. Either that, or it's high coincidence.. Either way, I can't afford to take my chances again, so I'd rather do everything to make it back to factory specs

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                        #12
                        I hate to ask the obvious but since you seem certain its the missing spring, why don't you replace it ?
                        Seat Shocks....I have passed the baton to John Christy from Ninestitch. Email John or Garrett at ninestitch1@gmail.com

                        https://www.r3vlimited.com/board/sho...86#post4944786
                        Alice the Time Capsule
                        http://www.r3vlimited.com/board/showthread.php?t=360504
                        87 Zinno Cabrio barn find 98k and still smells like a barn. Build thread http://www.r3vlimited.com/board/show...20#post3455220

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