Tech Support- Clutch slave bleed

I'm having a problem getting my (GF's Boxster) clutch to pump up after doing a trans out service (new PP, FW, fiber, TOB, pilot, arm, and pivot hardware). Never opened the hydraulic system at all. Slave had resistance/pressure when installed back into trans. Then no clutch, pedal to the floor. Ok, no problem, bleed it out. Pressure bleeder, pedal pushed to the floor (initially solo with a wedge, then GF held it to the floor later in the day). Can't get any pedal pressure. Put about a pint through it in 4-5 attempts. I've bled these systems before, without issue. I'm kinda perplexed. I'm thinking about reverse bleeding it tonight, pushing fluid from slave to master. Anyone have this issue that resolved it with some alternate technique? There has to be air in the system, probably master cylinder. Why won't it come out? Thanks in advance for any help, Mo

Sounds like you are doing it correctly. The only other thought is that the seals blew in the clutch master cylinder or in the slave cylinder. Sorry...not much help on this one.

Thanks. MC pooping out would be a huge coincidence, as it worked just fine before, and no leaking, but the thought has crossed my mind. I'm going to try upping the pressure before reverse bleeding. Been using 20 psi. I think max safe is 28 psi.

The google machine says 1.5 bar is 21.75 psi.

No more than 20 psi! https://www.renntech.org/forums/tuto...-instructions/

Yea, but I found this thread, http://986forum.com/forums/performan...tch-slave.html where BYprodriver runs 28 psi and gets out a bubble after similar condition. I also seem to remember reading a limit (bentley? or 101projects?) that reccomends 22 psi and a "not to exceed" of significantly higher (28 psi?). Sorry don't mean to be discounting at all, all advice appreciated! It's really frustrating when you gut your SO's car, then something seemingly so simple holds you up. I've been bleeding (knuckles included) for a long time, and it always seems so simple.

I had a similar issue when I had to bleed my clutch. It took me several times to get it to pressure. Here is what I did: 1. Use a pressure bleeder, max 20psi 2. Do not overfill the master cylinder 3. Use a bar or something and press the clutch down all the way, and hold it there 4. Bleed the clutch fluid out at the slave cylinder. Let it run for at least 30 seconds. 5. Close the bleeder valve 6. Release pressure on the pressure bleeder 7. Release the clutch. If clutch is not up to pressure, repeat this process. I had to do this 3 times before I got rid of the air bubble and it got up to pressure. I used 2 liters of fluid, the first one did a complete flush, and when I got to the second one I caught the fluid from the slave clutch into a clean container and re-used it in the pressure bleeder.

Thanks. Will be patient and try more standard bleeds. Have done 4-5 already. But I'll start with a clear head.

Try pumping the pedal, mine was the same , I had my farther inlaw on the pedal I would open the slave bleed nipple as he was applying downward pressure then close it when the pedal gets to the bottom then release the pedal back to the top and repeat a few times then when you can feel a bit of a pedal coming at the bottom just pump the clutch pedal like a madman for 20-30 times without any bleeding, on mine I could feel the pedal coming to me then, repeat the process if it doesn't sort it on the first go, sometimes this works better on the clutch than the pressure bleed for some reason, back to the old school !

Did fluid spill out between the transmission and engine? I�m not sure about boxsters but with 996 it�s common for the slave cylinder to be misaligned with the clutch release fork. The result is what you described - pressure and then nothing as the piston slips past and the slave cylinder explodes apart.

Quotes source post: 15298041

^^^^ this is my thoughts as well....

Quotes source post: 15298041

Been there, done that on my M3. Definitely didn't shoot the rod out. Actually would be very hard to misalign this set up. Pumped the pedal like a 16 yo with a hustler magazine. Couldn't get even a tiny bit of pedal...ever. Pressure bled over a gallon of fluid through it. Reverse bled, pushed and pulled. I've tried every method I've ever heard of. All I can come up with is that the MC failed somehow/randomly while it was apart.. I think my only option before I get out some explosives is to replace the clutch MC and slave so I know all components are good. What a bummer. It was a great job and I had fun doing the work on this car. Motor seems to run great now (vario cam pads, plug tubes, plugs, cam tensioners, IMSB seal removal, and cover seal, rms). All went smooth and fast relatively. I've probably got 5 hours into a 1/2 hour bleed job. Sheesh.

Quotes source post: 15297523

^^ This^^ When I did my engine/tranny out and replaced my clutch I had a similar experience. It seemed to take forever to get the air out (I didn't use a pressure bleeder) but eventually the pressure came up and it's been fine ever since (about a year and a half now)... Good luck

:Yea, I wish it would've just taken a long time. I bled this thing for 5 hrs and I think I refilled my qt of brake fluid 5 times. For the record, the Bentley says 1.5-2 bar of pressure. Not to exceed 29 psi. I wish there was a magic button to make this problem go away. Ordered new slave and mc this morning. Porschetech3 have you ever had a random failure occur like this? When I pumped the pedal furiously, I could hear a bit of squish coming from the mc. Like it was dry, and maybe air coming past the seal. I'll update if I find something out.

Were there bubbles coming out the bleeder valve while you bleed?

Not even the first time Ahsai. I fully expected to lift the pedal up and have full pressure. 30+ times and 5 methods later, still nothing.. Ordered parts, that's all I know how to do at this point. No leaks, baffling.

Have you tried removing the slave cylinder and make sure there's still pressure on it when you try to reinstall it?

Quotes source post: 15299472

There was pressure/resistance when I initially installed it. Had to push it in place pretty hard to get the bolt in place (and the bolt flange into the recess). Because of that, I didn't think I would even need to bleed it. Haven't removed it since. Might be worth a try. But at this point if I have to remove the mc (or slave again) I'll just replace them. MC looks like it's going to make me suffer a bit.

Quotes source post: 15297523

When I was bleeding my clutch slave cylinder, I didn't do step 3, and it seemed to work fine: clear fluid came out, then some air bubbles came out, and finally only clear fluid came out. Can someone explain the reason for step 3? If the clutch master cylinder is anything like the brake master cylinder, depressing the pedal cuts off the reservoir from the hydraulic circuit, so the pressure bleeder cannot force fluid down to the slave cylinder. Or am I missing something? thanks

Quotes source post: 15299133

Nope. Every time I have seen these symptoms after slave cylinder R&R it has been due to the push rod missing the indentation of the release fork. I have seen the push rod cocked in there in a way that it didn't blow the piston and seal out of it though. It usually blows the retaining clip , piston and seal out from repeated pumping. Are you sure you have installed all compatible components? A failure of the slave or master cylinder at the exact moment you put it back together is highly unlikely, but there is a first time for every thing.

Yes, I have high confidence that the slave is installed correctly. The clutch arm was right there shiny new (OEM) in the opening. I had the trans and motor lowered and was on a lift at eye level when installed. It looked like it would be hard to miss the indent with the rod. When I missed with my M3, it made a noise, pedal had pressure, then went to the floor, then fluid on the ground. My gut is telling me the mc isn't pushing. I'll know when I replace it, and slave if I'm going crazy or not.

Quotes source post: 15299810

+1

I agree as well.

In my case the rod and entire assembly came out of the slave cylinder while the transmission was out (clutch was pressed by my kid). Big mess on the floor, lots of fluid loss and air in the clutch line. It took me a long time to get that air out, I thought there was something wrong/broken but it finally did work after I repeated those steps several times. I did see a lot of air bubble coming out, but some of that was leaking by the bleeder valve vs. coming out from the line. I found it to be about 1/8 of a turn between being open enough to bleed and too much to let air back into the bleeder screw.

Other thing to try is between steps 5 and 6, depress the clutch several times, and then re-bleed. Might release some of the trapped air.