New Clutch Slave, Pedal Stays On Floor

[OK-944]

Rebuilt engine with fresh Sachs clutch kit installed in car, but gearshift not yet connected to trans (have not yet started car).

Before I re-installed my engine, I replaced the clutch slave and, as I held the slave just below the level of the brake fluid reservoir…I bled the system by feeding brake fluid through the slave’s bleeder valve until the fluid level came up in the reservoir. Only noticed a few bubbles during this process…not nearly what I’d expected.

With my engine back in the car, and the clutch slave installed…the clutch pedal now goes to floor and stays there - but I only have to lift the pedal slightly before it springs back up (indicating that clutch return spring is fine).

My assumption is that my efforts at bleeding the slave cylinder created a bubble in the master cylinder - and that I need to re-bleed, and possibly re-think my bleeding process. Sound about right? Any suggestions? Thanks!

[944 Ecology]

Re bleed. Again and Again. Have extra fluid on hand.

[9FF]

Correct, you still have air in the system for the pedal to remain floored. I find the best was is using a dry motive to apply pressure while bleeding the system old school with someone pressing and releasing the pedal while you crank open and close the bleed screw.

[peteb]

Hello,

Maybe I can offer some reassurance.

My 944's slave cylinder failed overnight in my garage. It was fine when I parked the car. The next morning I pushed on the clutch pedal, it went to the floor and stayed there. There was a puddle of brake fluid under the slave cylinder.

The the 944's power spring (the spring attached to the pedal inside the car) will account the pedal on the floor. If there is no brake fluid, or brake fluid and air mixed, the clutch's spring will not be able push back on the power spring and the clutch pedal stays on the floor.

I just needed to replace the slave and bleed the system to fix this issue. I used my brake power bleeder. It took a while and a fair amount of fluid. It may help to lift the car level or slightly unmount the slave cylinder such that the air bubbles will travel to the back of the cylinder and the bleed valve. This could be an issue if the front of the car is lifted front more than the back.

Your clutch install is most likely good.

Peter

[OK-944]

Seeing as how my clutch pedal will stay down if pushed...should I leave it in this "down" position as I attempt to bleed the system?

Or maybe have someone inside the car intermittently lifting and pressing the clutch pedal...until it hopefully starts to spring back on its own?

Or just leave the clutch pedal alone?

Then again...now that the slave is actually installed, I'm thinking that the technique of feeding the system fluid through the slave's bleeder valve might work better than when I'd been holding the slave up high (prior to installing the engine)...so I might try giving this another go first, and hopefully enlist my dear wife to watch for bubbles up in the reservoir. Comments?

[jjeffries]

I'd leave the pedal in the up/natural position and keep bleeding it from the slave cylinder's nipple. It will work eventually.

John

[djnolan]

https://youtu.be/wdf--suwqw0?t=195

[Rasta Monsta]

Did you verify the rod is seated in the fork?

[OK-944]

Pretty sure the rod is in the fork...but I will remove the slave to verify this.

...and DJ - that video is the one I used as a basis for my original slave bleeding. But I'm thinking that it might work better with the slave in its installed position, instead of how I did this with the slave held up high.

I think I'll check the rod placement first, then see if I can bleed "conventionally" with Motive pressure on top...and if this does not work, I'll re-try feeding fluid through the bleeder valve.

[onZedge]

I recently replaced all the clutch hydraulics in my 924S. After looking at a lot of different procedures in these forums, I consolidated and developed this procedure that worked for me the first time I tried it (your results may vary):

This procedure assumes you have replaced one, or all, of the hydraulic components in the clutch system:
a) clutch slave cylinder
b) clutch master cylinder
c) clutch pressure hose
d) clutch reservoir hose.
This procedure also assumes the clutch mechanical components are in good working order, the clutch power spring has been adjusted to the correct length, and the master cylinder extension rod has 3mm of free play.

• Removing the starter is optional but improves access to the clutch slave bleed nipple.
• Raise the rear of the car to get the clutch slave at least level or higher.
• Pre-bleed by using either a syringe to pump brake fluid into the clutch slave cylinder from below, or by using a motive power bleeder to pump brake fluid in from above.
• Close the clutch slave bleed nipple.
• Make sure the brake fluid reservoir is full.
• Find the clutch inspection hole in the bell housing where you see the clutch slave extension rod contacting the clutch fork.
• Insert the flat blade of your tool (large screwdriver or small prybar) in front of the fork.
• Pry the fork back to push the clutch slave extension rod into the clutch slave body.
• Sweep this motion several times, while keeping pressure on your tool to limit the speed that the slave piston returns each time.
• Make sure the brake fluid reservoir remains full.
• While kneeling with the driver’s door open, grasp the clutch pedal firmly.
• Manually push pedal to floor and pull it up about an inch or two. Repeat this motion about 10 times.
• After 10 pumps or so, slowly pull the pedal all the way up and then repeat the short travel 10 pumps or so again, and finish by slowly pulling the pedal all the way up.
• Top off the brake fluid reservoir.
• Now manually pump 5-10 full strokes.
• Sit in the seat to assess the clutch pedal feel.

[OK-944]

Finally got some sense into my head...after having spent way too much time pumping air down and out through the slave - to fill the Motive with brake fluid! After this it worked like a charm!

Yup...I'd been using the Motive dry - which works fine for brakes as long as the reservoir level is frequently checked. My thinking had also been that using the Motive dry would somehow keep it "fresher." Jeesh....no more - I'm always going to run it wet from now on! Just a little rinse with Alcohol afterwards and it good to go.

Oh...and that O2 sensor? After having been filled with dread from so many videos laying out all sorts of horror stories...the thing basically just came out! Sawed it off and used a breaker with a 22mm multi-point...a bit of PB blaster, and while it did take a bit of working back and forth, it eventually came out without heat.

Two out of three ain't bad...as my luck ended when I cracked that plastic cup-bushing as I was prying it off of the ball at the bottom of my gearshift - probably a blessing in disguise as I shouldn't trust such a highly stressed, 35 year old piece of plastic.

[Mike Goebel]

Originally Posted by OK-944

Finally got some sense into my head...after having spent way too much time pumping air down and out through the slave - to fill the Motive with brake fluid! After this it worked like a charm!

That's GOLD right there man!!! It always cracks me up when people have so much advice but the answer is so simple in the end. Don't worry it has happened to me on many occasions.

Mike G.