[s-cars] Bleeding hydraulic clutch line - possible mistake? (long)

Dave Ellis UrS4 at sympatico.ca
Sat Nov 5 18:15:05 EST 2005

So I decided to bleed the brake fluid on all four corners as well as the 
hydraulic clutch lines on both my Audis today.  It's been two years 
since I last did the A4 and this was the first time for my '93 S4.

So I pull out my Motive bleeder and three litres of Pentosin, and go at 
it.  The A4 went smoothly (even bleeding the clutch line is easy on it), 
and then I moved on to the S4.

I've owned the S4 for two years, and just did the brakes last month. 
The original owner had the brakes done at the local Audi dealer just 
before I purchased it, and so I figured the brake fluid would have been 
flushed at the same time.  Apparently I was very wrong in this supposition.

The rear passenger and front driver's side lines yielded dark brown 
fluid with a worrying amount of small particulate matter.  The other two 
callipers/lines were not too bad, though the brake fluid was noticeably 
dark.  When it came to bleeding the clutch line, I ran into problems.

First off, I'd just like to say what a @$%&^&! pain in the a$$ it is to 
bleed the hydraulic clutch line on the UrS4.  Getting a wrench up to the 
bleed nipple and then finding room to manouver it is quite a challenge. 
  The A4 crowd keep complaining about how hard it is to bleed the clutch 
line on that car, but it's dead easy compared to the S4!

When I did finally manage to get a line over the bleed nipple for the 
clutch from below and loosen the screw, no fluid at all flowed.  So with 
my wife helping from above, she raised the pressure first from 5psi to 
10psi, and then finally to 15psi on the Motive bleeder.  Still no fluid 
flowed.  Loosened the bleed nipple more (there went some more skin from 
my knuckles), but still no fluid.  Hmmm...

I ask my wife to press the clutch pedal, and I hear a loud *snap*.  Uh 
oh.  My wife tells me the clutch pedal was stuck, and when she pressed 
harder it suddenly dropped to the floor.  But at least now fluid is 
flowing out of the bleed nipple.

I don't think from the look of the fluid that came out the clutch line 
had ever been bled.  What came out was black sludge full of mud and 
other unsavoury goo that had little resemblance to any brake fluid I'd 
every seen before.  As I watched the mess make it's way down the drain 
tube I couldn't help but think I should have noticed some problem with 
the clutch pedal feel with fluid in this condition, but never did.

Eventually once the fluid was running clear I closed everything back up 
and went to move the car off the ramps I had it up on.  I get into the 
car and find the clutch pedal on the floor.  Not good.

I raised the pedal back up by hand against some resistance, and was then 
able to pump it up and down a few times until it felt "normal" again.  A 
quick drive around the block and everything seems good.  Brake feel is 
nice and solid (better than before), and clutch engagement is now *much* 
improved (and very different) than I ever recall it being before (go 

So to end this saga with a question, have I damaged either of the clutch 
cylinders?  Is it normal for no fluid to flow until the clutch pedal is 
depressed when bleeding the clutch line?  Any comments or insight is 

Slightly worried,

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