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?

[dghii]

yes. you need to check connections and re-bleed before jumping to any conclusions.

[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 until the bubble you see in the line had passed..




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.

[pilot4fn]

Sounds like your clutch fork is being misaligned from the other end (bellhousing end). If this is the case, you need to take the transmission out to get the clutch fork back in to it's correct place.

[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 used my borescope to check in the hole and the clutch fork is there and doesn't seem to be flopping around.

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?

[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]

Originally Posted by pilot4fn

Sounds like your clutch fork is being misaligned from the other end (bellhousing end). If this is the case, you need to take the transmission out to get the clutch fork back in to it's correct place.

Yeah, that's what I'm suspecting.

[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 making sure to keep the fluid above the "add" mark in the reservoir.



I'm not seeing any leaks. The master cylinder is dry, as is the area up by the reservoir. I'm keeping the fluid above the "add" mark when bleeding. 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?

[pilot4fn]

Sometimes while doing the vacuum bleeding process, the bleed nipple threads leak a bit of air to the bleeding hose - visibly shows that there is air in the system.
I prefer pressure bleeder or other person sitting in the car pressing the clutch pedal for that reason.

[clueless1]

Curious, what is the indication to change hydraulics?

[jluetjen]

Originally Posted by pilot4fn

Sometimes while doing the vacuum bleeding process, the bleed nipple threads leak a bit of air to the bleeding hose - visibly shows that there is air in the system.
I prefer pressure bleeder or other person sitting in the car pressing the clutch pedal for that reason.

True. I'd periodically check for that by applying a vacuum with the bleeder nipple closed. No bubbles. So that kind of eliminates that. Also, when I'd complete the bleed and try the clutch, it wouldn't work.