Trying to bleed a hydraulic clutch slave cylinder?
 

I’m at wits end with a muscle car aftermarket hydraulic clutch bleed. This has a reservoir up on the firewall with a rubber hose to the clutch MC, which has a stainless hose down to a slave cylinder. The bleeder screw is on the slave cylinder.
Bleeding the normal way like on brakes gets nearly no fluid out b/c the piston barely budges from a full stroke of the pedal. I’ve removed the pushrod from the slave cylinder and pulled the piston well out into the bore, uncovering the bleeder screw, and added a c clamp to prevent pedal strokes from pushing the piston out the end. Even with that rig, and my pressure bleeder pushing fluid down from the reservoir, I have virtually no pedal even though I’m getting no air. I should have a completely hydro locked immovable pedal now and I don’t. I’ve pissed 2 quarts of brake fluid through the system while in denial that what I’m doing will dislodge an air bubble and work eventually.
Just stepping away from it to cool down and figured I’d post on pelican OT in the event that anyone has any Jedi mind tricks for these that I’m not thinking about.

I have this tool called the pheonix injector. I pushes fluid, from the bleeder , up to the reservoir . It works in 3-4 pumps every time .
Otherwise, bleeding by standard pedal method, can take forever , and maybe not even possible .
I try to fill and burp out any air bubbles on any slave I install, before I even connect the line .
Good luck, it can be frustrating

At least there's one good thing going for you.
Air will always rise to the top, unless it doesn't have an escape route.

+1, this has been the route to success for me... bench bleeding the MC and slave as much as possible.

What components were replaced before bleeding?

bench bleed it

Master Cylinder o-ring has a nick in it and has blow-by? replace M/C?

Hopefully , the slave is mounted outside of the bell. Unbolt the slave, open the bleeder, and tilt it in a way, that the bleeder is in the highest possible point. Hopefully, you can get it to drip Let it drip for a few minutes . If you do not have a pedal at all after this, close the bleeder, and just pump the mother 100 times . If you have to use your hand , to pull the pedal back up, do it that way . You may just start to get pressure this way . Once you have any sort of pedal, you are halfway home . Id finish up with a standard bleed, by try to not push the pedal all the way to the stop .
Good luck. I remember the frustration when I would get a tough one . You got brake fluid running down your armpits, and still cant get it to work
If its an internal slave, you can try to rig up a way to push fluid up through the system, or may even be able to force fluid down through it . Usually, there is a tiny breather hole in the cap of f the resevoir. You can use an shop air gun to slightly pressurize it, and hopefully force fluid down through .

can you bleed it on the bench first? its been decades, but i vaguely remember doing it in a vice on my bench. i ran the outlet hose up around back into the reservoir.

thinking back, this may have been a brake master cylinder. sorry

You said it all right there.
I unbolted the slave and did tilt up the bleeder side. Via that, and then having the motive pressure bleeder constantly pushing fluid through from up top, I would get some air out. Then I would push the piston back in, with the bleeder open, and get a little more out. Close the bleeder, Put the clamp back on, get back out and pump the pedal a bit to move the piston back out, and repeat. Do that about 15 times, which is practically a CrossFit workout with burpees when you think about how many times I’m going from the floor to in the car.
At the moment I reassembled to see where I am and I have a halfway pedal. I’m walking away again to think about whether I should try the standard push pedal open screw close bleeder lift pedal route from here to get a GOOD pedal, or if that will send me back to ground zero.

Now that you have some pedal, you should be good to go. When you come back from your little hissy fit ( I take them also ) , don't touch the bleeder, just sit in the car and pump the clutch pedal over and over till it feels normal again .
Once you get mostly normal pedal, Id just crack the bleeder and see if you get a bubble or two out.
Timely thread. I just finished up putting a clutch in a 2015 Mustang today.
There is NO Bleeder??? I was sitting there looking at it thinking , this should be fun . I filled the slave then bench bled it by submerging the line in fluid . Then I hooked the hose up loosely before I bolted the trans back to the motor, and when I pushed the trans back on the motor, it spit a bunch of fluid out .
I was surprised , that when I lowered it down, and tried it, it was already bled and h ad a perfect pedal . I was expecting to have to fk with it for a while to make it work
Hope yours pans out for you

what angle is the car at? I know you've talked about unmounting the slave and angling it up to have the bleeder at the top. What about the master cylinder angle?

longshot....

Also, I'm sure you've googled "brand XXX bleeding problems" Someone with the same setup has been there before.

Worst night of my automotive life was new years ever circa 2003. Wife had left, and I was outside in the dark at midnight in 20 degree weather doing the fluid running down the arm thing while trying to hold a flashlight/ etc. on my 951. Hands were freezing holding the cold parts. As the rest of the world started screaming when midnight hit, fluid shot all over my face.

I thought to myself "Self, I am really unhappy at this moment."

Out of all the clutches I have ever done, and that is a lot , I think 944's are one of the hardest to bleed. The way the hard line runs it has one section where the air gets trapped .
That is why I finally broke down and bought that tool .

https://media.tenor.com/images/40771...3c69/tenor.gif

***CLUTCH**** fluid!!!!
:D:D:D

Years ago I had a similar problem, pretty sure it was my 1984 533, if I remember right that clutch master cylinder had a small spring in it to return the master cyl piston back up, when that spring broke the pedal would get lower with every use until the clutch would not release. For a couple of days I attached a large syringe full of brake fluid so I could pressure the piston back up and drive the car while waiting for a part, real pain in traffic when I knew it would work for 10 uses before needing an injection. LOL