Replaced Clutch Hydraulics -- Now I don't seem to have full pedal travel

[jluetjen]

I just replaced my clutch hydraulics (master cylinder, the 2 hoses to the reservoir, and the slave cylinder), and got everything bled (with the pedal all the way down to the floor). But now I seemed to have lost some pedal travel at the bottom of it's travel (i.e. when my leg would be fully extended). I also can't put the car into gear, so the clutch is certainly not activating.

I'm thinking I'm going to need to bleed the system again.

Any ideas?

[Ronpor]

That would be a good idea.

[CarGuyNeil]

Bleeding the system again couldn't hurt.

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[jluetjen]

Figuring that I might have not bled the master cylinder successfully, I used the previous feed hose (which I had cut to remove) and made a hose to go back into the reservoir. It seemed to work fine, but I needed to use some pliers to pinch it off when returning the pedal to the top of it's travel.




Then I went back and re-blead the slave cylinder. Something didn't seem right, and then I noticed brake fluid dripping onto the floor. Long story short, the push-rod pushed out of the cylinder. Why did that happen? I'm not completely sure but when I put my finger into the hole in the bell-housing, I don't seem to be feeling anything but pressure plate. I would expect to feel the clutch release arm in there.

Did the release arm fall out of position or break? I'm not sure, but my borescope is recharging. I'll post what I find. But I suspect that I'll need another slave cylinder now.

[jluetjen]

I installed this slave cylinder on my car, and the piston blew-out while bleeding the system. I had bled the system a few times with the pedal fully depressed (including bleeding the master cylinder separately), but still the clutch wouldn't work. The best that I could get is that the pedal would go 4/5 of the way to the floor, but never disengage the clutch. Finally I noticed fluid leaking from the slave cylinder, and when I removed it, the piston had blown out. I've attached a picture of the slave cylinder that I removed from the car, and the piece that I bought (which I'm pointing to). They look identical to me. The part that I took off of the car was labeled Sachs, and had a VW part number 8E0-721-257. I don't see any identification on the 8E0-721-257-M-M38 that I received from our host, but the PN seems to be the same.
Can I just put the piston back iin the cylinder and try again, or is the product ruined now that the piston has been pushed out?

PS: I also looked in the hole with my borescope and the clutch fork seems to be there and not flopping around or anything.

Also, If the piston has pushed out of the slave cylinder, can I just put it back in? Or is the slave cylinder trash at that point?

[Matt at Pelican Parts]

If the piston popped out it could mean that it is not aligned with the clutch fork. Your slave cylinder may be compromised but its tough to say without knowing if a seal broke when that happened.
We have a pretty good tutorial on a 986 overhaul of the hydraulic system. You may have already done everything listed but I figured it's worth including just in case:
https://www.pelicanparts.com/techarticles/Boxster_Tech/45-TRANS-Clutch_Hydraulics/45-TRANS-Clutch_Hydraulics.htm

[mistertate]

Yes, sometimes you can get lucky and push the piston back in and never have a problem again. Maybe find a way to test it before you commit

[jluetjen]

OK. I just replaced the slave cylinder again through the good graces of our host.

I put everything carefully back together, I lubed the tip, rebled the master and then the slave.

Still the pedal didn't seem like it was getting full travel, but I would hear motion from the back of the car (the engine was off).

I started the car on jack-stands, and I couldn't put the car in gear. On the third or fourth pump, the pedal went to the floor, and it once again it blew the hydraulic line out of the slave cylinder.

My guess is that something mechanical in the throw-out mechanism has failed. Anyone else ever run into this? Any thoughts or experience based observations?

[jluetjen]

I sent it into a shop since I didn't have the bandwidth to pull the transmission myself right now (my 911's transmission is still on my workbench). They said that I was down to the rivets on the clutch, so they replaced the whole thing: Clutch, dual-mass flywheel, fork, post, slave cylinder (again) etc. I got it back, and took my wife out to dinner in it. It worked great! When we got back, I couldn't get the car into first gear.

It seemed like there may have been some air in the hydraulics. So I figured that I'd bleed it and be good to go. So I took out my vacuum bleeder, put the pedal to the floor and lo and behold, bubbles came out of the slave cylinder. And more bubbles. And more bubbles. I've since run about 3 liters of hydraulic fluid through the system, and I'm still getting tons of bubbles.



I'm not seeing any leaks. The master cylinder is dry, as is the area up by the reservoir. When I close the bleeder valve I'm not getting any bubbles, so it's not like the bubbles are leaking past the bleeder nipple.

Any ideas?

[jluetjen]

...And now as Paul Harvey used to say ..."The rest of the story."

I took they car back to the shop and they tracked the problem back to the master cylinder. A word from the wise folks at "The Little Foreign Car Garage" in Waltham, MA -- Always put a block of wood under the clutch pedal when bleeding the clutch hydraulics. When I was bleeding the system (with the pedal pressed by a piece of wood wedged between the clutch pedal and the driver's seat), as soon as I opened the bleeder, the clutch would be pulled to the floor by the helper spring. Do that enough times and you'll blow out the seals at the bottom of the master cylinder as the pedal bottoms out.

They were very gracious about fixing an owner inflicted problem on the car, and shared the piece of wisdom for future reference.

[CarGuyNeil]

Very interesting. Thanks for sharing. Good information.

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[Matt at Pelican Parts]

Oh wow the master cylinder. Interesting. Thanks for passing on the info. Good to hear you're back up and running!

[GrayM]

Sounds like you have a good garage there!