Clutch Slave Cylinder DIY problem – Help please.

[BoxsterBob - CA]

I had noticed brake fluid loss (warning light and topped off twice), but haven’t seen any drips, and the clutch pedal is occasionally sticking half way back on the return, requiring me to pull it back with my toe. I replaced the Clutch Master Cylinder and bled the clutch, but the sticky pedal still occurred. Yesterday, I removed the slave and noticed leaking fluid, so that appears to be the problem. I ordered and installed a new slave cylinder, with the pedal at the floor, using my Motive bleeder, I bled until no more bubbles, tightened the bleeder tip, pulled the pedal up and gave a few pumps. I released pressure on the Motive, but when I went to start the car, the pedal would not go the last inch or so to engage the clutch/starter sensor. When I pushed harder, the pedal went to the floor and I heard a “pop” and fluid leaking at the tranny. I removed the slave and found the guts in pieces. (see below)

I read that not aligning the slave plunger with the clutch fork can cause this catastrophic failure, so today a bought a new slave, installed it as straight into the hole as possible with the hydro line disconnected and the bleeder valve open. I tightened the mounting bolt, re attached the fluid line, and closed the bleeder valve. With the pedal on the floor, I pumped the Motive up to 22 psi, and bled the valve until no more bubbles. I pulled the pedal up and gave it a few pumps.

I removed the Motive, but the pedal WILL NOT extend the last inch to the floor to engage the started sensor. I don’t want to force it and blow the new slave. What am I doing wrong?

Today, I removed the slave and got my cell cam in position to show the mounting hole and clutch lever (fork). (Below) The indentation in the fork ensures the plunger tip really has nowhere to go but into the divot. I tried to insert my finger to see if I could depress the lever, but the contortion required to get my finger in, eliminates any leverage I have to depress the lever. I don't know if a human finger should be able to depress it. Everything appears to be where it should be, I just don't know it the fork is somehow frozen.

1999 Boxster, 5 Speed, 140,000 well enjoyed miles. The part was purchased from Pelican Parts.
Brand: Sachs, 1999 Porsche Boxster Convertible
Part #: 8E0-721-257-M-M38

Clutch slave cylinder mounting hole - top left side of the transaxle, showing the clutch fork.



I added a dab of lube to the fork indent and the plunger tip and reinstalled the slave... again, connected the fluid line and bled successfully with the pedal at the floor. When I lift the pedal and pump a few times, the pedal will not hit the floor, it stops about 1 inch from the firewall. It feels like the fork is not depressing. Since the clutch pedal will not hit the floor, the sensor will not let me start the car. I did start the car when the cylinder was removed and the pedal was on the floor before reinstalling, but that made no difference.

Any suggestions?

Here are a few shots of the carnage from yesterday’s attempt.

[arthrodriver]

First, I do not own a Boxster. Have you ever replaced the to brg or clutch? How has clutch been working prior to incident? Is "fractured looking " part steel or rubber?

[Meir]

some missing information.
1. did you replaced the clutch before, or just working on slave and master?

you wrote: "With the pedal on the floor, I pumped the Motive up to 22 psi, and bled the valve until no more bubbles. I pulled the pedal up and gave it a few pumps.

I removed the Motive, but the pedal WILL NOT extend the last inch to the floor to engage the started sensor. I don’t want to force it and blow the new slave. What am I doing wrong?

why did you pump the pedal with the motive bleeder still connected?
not saying that's your problem, but you are suppose to disconnect the bleeder and put back the cup before pumping the pedal.

[BoxsterBob - CA]

Thanks for the replies. No, I did not replace the clutch. It has 140k miles on it, but has been working fine. It was the fluid loss and the sticking pedal that prompted the Master Cylinder, then the Slave Cylinder R&R.

I did remove the Motive prior to pumping, that was a mis statement. With the pedal to the floor, I connect and pressurize the Motive, open the bleeder valve, once bubbles have stopped, close the valve, disconnect the Motive and pull the pedal off the floor, give it a few pumps.

It is at this point that it will not return all the way to the floor.

The fractured part is plastic.

[Meir]

in that case it is very strange.
you are doing everything right and the fork is right where it should be.
i came across a failing slave cylinder when the fork has broken, and the cylinder travel was longer then it should be.



in your case, it looks like the fork is not reaching its full travel.
assuming you are using the correct part (and it looks like it), it looks like something is wrong with the fork and throw out bearing. i know it doesn't make sens as it use to work fine before the slave cylinder failed, but maybe the hydraulic fluid in the trans case, cause the bearing to seize on the Guide Sleeve.
if it was me, i would probably drop the transmission to see what going on in there, and give it a good clean. it might be the time for a new clutch.
at 140 you should be at your second clutch replacement.
however, i'm not a pro, so maybe you should wait for one of them to chime in.

[BoxsterBob - CA]

Thanks Meir, I was pretty sure I'd done it right, I was just wondering if I missed something. My next step is to flatbed to my mechanic and replace the 140k mile original clutch and upgrade the IMS bearing and add DOF.

[Steve Tinker]

Before flatbedding, why not try manually bleeding the system? There seems to be a problem only with the last inch or so of pedal movement, no?

Its a pain to get a helper to press the clutch pedal after manually loosening the slave bleed nipple with the clear line attached, but you should have no air in the system now and if you are under the slave when your helper depresses the clutch, you can see its travel.
I'll bet once your helper has pushed the clutch down a couple of times with the nipple open, then holds it down while you tighten the nipple, you should have a functioning clutch.
But I have been known to be wrong before....

[BoxsterBob - CA]

That is a good suggestion, Steve. I have tried bleeding a second time AFTER the pedal has been pulled back off the floor and pumping. I used a 2x4 pressed against the pedal (1 inch from the floor). Reconnected the Motive and pressurized to 22 psi, as soon open the bleeder, the pedal hits the floor and the 2x4 falls. I close the bleeder, disconnect the Motive, pull the pedal off the floor and pump, still not traveling to the floor.

I will try the manual process tomorrow.

[arthrodriver]

Most slave systems are similar. (Remember I do not own a Boxster) If your slave is higher than the master you could try gravity . Judge it and then if necessary raise the front of the car so it is slightly higher than the slave . Open the bleed nipple with a clear plastic tube to see if flow begins. You probably know not to let your master reservoir go dry (or even get low). I have done this and then applied a vacuum gun to the bleed nipple, even alternating with a full depression of the pedal. Usually the pedal will come up in steps...quarter , then half then full hard.

But the resistance off the floor is troublesome. I did not want to mention it but someone already has suggested trouble in the stack-up...fork-to brg... and once I had disc disintegrate and a piece jam open the pressure plate. Hope this is not your case. (Do you drag race?)

[BoxsterBob - CA]

I will try the manual bleed today. The clutch was working fine (for 140k miles) and I don't drag race, however the odds that some fluid has got in the bell housing could have tipped it over the edge. All the bleeding so far has been by the book, the fork is in the right position, it just appears to be frozen.

Is there a way to bypass the clutch sensor to start the car? I thought I might try starting the car in gear with the wheels in the air just to see if it gets the clutch bits moving inside.

[Steve Tinker]

If you are talking about the clutch cutout switch, even pushing the clutch pedal halfway down should disconnect the micro switch.
If that doesn't work, just pull off the 2 wires going to the switch connector and jumper them together with a paperclip or short piece of wire.
Just be careful not to push the pedal down to the floor as you may get the same slave cylinder breakage as you had originally....

[BoxsterBob - CA]

Latest on the Slave Cylinder Saga... I had my wife depress the clutch while I opened the bleeder. I did see a few bubbles. Once the pedal hit the floor, I closed the valve, had her pull the pedal back to the normal position and repeated this about a dozen times. No more bubbles were present.

The clutch pedal continues to stop just short of the floor and the car won't start due to the sensor not triggering. I put the wheel back on, removed the jack stands and rolled down of the single ramp supporting the passenger side wheel.

My driveway has a slight slope, and at this point, I noticed when the car was in gear, the tranny held the car in place. If I depressed the clutch as far as it will go, the car will roll, release the clutch and the tranny engages and the car stops. I'm wondering if I may have mucked up the sensor??

Tomorrow I will try bypassing the sensor and see how the clutch operates.

[arthrodriver]

The switch is probably a simple make/break. If you can see the +12v and return terminals remove the wires and use a little lite, your DMV beep function or volt setting and observe when working the switch. I had a switch with an adjustment arm...serrated so it could be set for the pedal deflection. Lay on your back and take a look. I had apparently accidentally hit that arm while replacing the slave master.

[BoxsterBob - CA]

I was able to bypass the clutch starter switch with a simple male/male jumper and zip tied the wires under the dash. The car starts and while the shifting is a not as smooth as I'd like, as I'm sure the clutch is not fully engaged, the car is drivable!

Everything is back together, including the undercarriage engine skid plate that was not easy to manipulate back in position. So far so good, now I can drive to my mechanic for his input.

Thanks to all for the suggestions!

Bob

[Meir]

good luck Bob, and keep us posted.
just for future reference, the Reinforcement Plate will be easier to remove/install if you use a ratchet strap between the two sides supports that holds the plate.
part # 3 in the diagram:

[BoxsterBob - CA]

I'll consider the strap next time. I was able to use the floor jack to adjust the height of the vehicle and amount of weight on the suspension until I got the bolts to align with the holes in the plate.