Fwd: <E30> Replaced clutch master cylinder

[Pearson-Franks Family <pearsonf@xxxxxxxxxxxxxxx>]

Michael:

Ah, ye of little faith!  Of *course* people read this, but
most are very selective; either model bigots ("M3 or Die!")
or lazy . . . ;~)

Cool story about the Ford; bummer.

Lots of observations, since I am neither of the characters
described above:

- - I don't think you are done.  Yes, the hydralics in these
   guys are regular maintenance items; common to replace in
   100K+ vehicles.  So your dealer certainly stocks them.
- - But, I guarantee she/he stocks more slave cylinders.  Hmm.
- - The symptoms you describe are often highly temperature
   sensitive.  Cold = shrunken seals in the cylinders which
   = leakage.  You might want to consider this variable.
- - The plugged bleed screw on the slave cylinder belies one
   of your assertions; that you don't need to bleed this
   system unless it has 'debris' in it.  Yours seems to!  ;~)
- - You can try to clear the valve; but you really ought to
   replace the slave cylinder entire.
- - Your test technique of having a partner depress the pedal
   with the slave unmounted is risky.  Many the DIYer has written
   to the Digests in chagrin, that in so doing, they propelled the
   contents of the slave cylinder across their garage.  :(
- - In addition, your reasoning is good as far as detecting
   leakage goes, but it does not distinguish between the slave
   and the master leaking.  Op cit. above.
- - Lastly, the cruise control cut-out switch is adjustable; if
   the pedal is not coming up firmly (and I have had the same
   experience with the assist spring) it leads me to further
   suspect the slave cylinder.
- - And *really* lastly, can you tell my morning caffeine is
   pretty on-line?!?

Have fun; having fun:  Larry F.

>Date: Thu, 06 Apr 2000 23:05:50 -0400
>From: Michiel van Wessem <jmvw@domain.elided>
>Subject: <E30> Replaced clutch master cylinder
>
>Hi.
>
>Tuesday, on my way home, the clutch started to engage while I had the pedal
>down. Also, the clutch pedal wouldn't come up much anymore. At first, I
>could lift the pedal up by putting my foot under the pedal and the clutch
>would disengage long enough to shift quickly if I pressed it down quickly,
>but I had to be quick because the clutch would engage all by itself while I
>had the pedal down. Soon enough, it became so bad, I couldn't shift anymore.
><snip>
>I had my wife hold down the clutch pedal while I removed the slave cylinder
>from the transmission. I wanted to see if I could push the piston in. I'm
>kind of smug about this: if it would push in, no matter how slowly, the
>master cylinder had to be faulty. Because I hadn't seen brake fluid, the
>fluid had to be leaking back up towards the brake fluid reservoir.
>
>Indeed I could slowly push in the piston. The next day I bought a new
>master cylinder (fortunately, a dealer had this in stock; the dealer was
>expensive, but renting a car was more expensive).
>
>I installed the new cylinder the same evening and that fixed it!!
><snip>
>- - I broke the pedal's "compression spring", but even without that thing the
>clutch works fine. It's just that sometimes the cruise control switches off
>because the pedal isn't pushing against the clutch switch hard enough. I'll
>replace it when I get a new one in a few days.
>
>- - This problem was not in the clutch troubleshooting table at
>http://www.bmwe30.net/, but the fact that the dealer had that master
>cylinder in stock might indicate that it's a common problem.
>
>- - I wanted to bleed the clutch, but the bleeder opening on the clutch slave
>cylinder didn't let anything through. Still, the clutch works fine. My
>conclusion is that it doesn't matter at all if there's some air in the
>clutch hydraulic system - the forces aren't anywhere near that of brakes.
>The only reason I see for bleeding the clutch every now and then is to get
>any possible debris out of the lines.
>
>Anybody really read this? Well, thank you!
>
>Michiel (325es <http://www.monmouth.com/~jmvw/cars/BMW> )
>- ----------------
>From Jackson, NJ
>
>   e-mail at night: jmvw@domain.elided
>  e-mail while day: jmvw@domain.elided

- -- 
Larry Franks
Issaquah, Washington
'95 540i/6
'95 M3

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