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Advice on bleeding new slave cylinder...stepping on the clutch not working

(1994 F-150, 148K mi, 2WD, MT.)

Recently, I parked my pickup for roughly two weeks while I went on a working vacation. When I came back, I found I had a little friend (i.e. a field mouse) living in the glove compartment. Apparently, he had previously set up shop in the bellhousing of my MT, gnawing upon the slave cylinder as he got bored.

So, this meant I had to replace the [internal!] slave cylinder (and the clutch as I was at it). That’s all done…the problem that I’m having is that I can’t get it bled! 30-40 cycles of the clutch pedal later, and I still am not getting a firm enough pedal to return of its own accord.

How should I progress? I’ve read to vacuum bleed at the bleeder valve; I’ve also heard to reverse-bleed using pressure there. I’m feeling embarrassed 'cause bleeding (at least bleeding brakes) has always been straightforward for me.

If you are not getting any more air, all you have to do is push the clutch pedal all the way down and let your foot slide off of it, allowing it to spring up. Do this a few times and your clutch pedal should feel much better. It sounds stupid, but it works.

Mark’s suggestion is worth a try. I have had some success with that effort. Raising the front of the truck sometimes helps. Once the system is bled enough to drive, it will improve with time. The Peugeot clutch system is not very popular with shops in my neighborhood.

A good friend of mine just replaced the clutch in a 99 Ford Ranger with an after market clutch. The hub center was not the correct offset so the clutch would not disengage. He was sure he had air in the clutch system. You replaced the clutch too, could this have happened to you?

He could start the truck in gear with foot on the clutch and it would not move but if he moved his foot at all the truck would move forward. Also it would not go into gear at all once the truck was running.

Just a different thought since you say you changed the clutch but didn’t say stock type or any aftermarket upgrade type.

You did connect a short piece of snug fitting hose to the bleeder port and open the bleeder while pressing the pedal to initially bleed the system, I assume???

did you bench bleed the s/c? if not r&i and blled the cyl off the truck, then install and bleed at lines, etc.

I’ve never had a problem bleeding the slave clutch cylinder on my Corolla. Perhaps the F150 is more complicated. One thing to consider: It’s possible the master clutch cylinder is defective too. It may be allowing air to get in. A loose fitting of any of the hydraulic hoses could do it too. And there’s always the possibility the new slave is defective.

I bet @meaneyedcatz advice is what will make it work again. It is hard to get the air out of the system unless it has been bench bled.
You could try using a vacuum bleeder like a MityVac but there’s likely a huge slug of air in the system.

I implore you to try my suggestion of just letting the pedal snap itself up a few times before buying any more tools or removing the transmission again. Every internal slave cylinder I have replaced, including in my '98 F150 with the same transmission as yours, has required this procedure and nothing more. In fact, last time I had the clutch hydraulics apart in my F150, upon reassembly, all that was necessary was cracking the bleeder 3-4 times then sidestepping the clutch a half dozen times to make it good as new. It takes less than a minute and will probably solve your problem. Works for me every time, and I have never bench bled a slave cylinder.

Well there’s no way to bench bleed it now that it’s on the truck, removing it just to bleed it would be crazy. If you don’t have any way to vacuum bleed the system, mark9207 has the right idea. It will force any air bubbles back out the top through the master cylinder and back into the reservoir.

One time I had a front brake caliper on a late 70’s VW Rabbit that was giving me grief, hard to bleed and get all the air out using the “push on the brake pedal and open and close the bleeder valve”, you know, the usual technique to manually bleed brakes. So I got one of those hand held vacuum pumps and sucked the brake fluid out through the bleeder screw, and that worked. It’s worth a try if @mark9207 's method doesn’t strike pay dirt. It’s quite messy cleaning up the vacuum pump afterward is the main problem with this method.

On some problem child bleeding problems I use low air pressure. I’ve got an old firm rubber disc about 1/2" thick in which I’ve drilled a hole and glued a tire valve stem in place.
I turn the air down to about 2-3 PSI, hold the disc firmly on top of the fluid resevoir, and then pressure it up. This method will bleed them in seconds and wrestling with SAAB bleeding is what led to making this thing as they were notoriously finicky about the bleeding process.

It may be difficult to find a stiff piece of rubber to make one of these though. I would imagine something similar could be made out of an extra resevoir fluid cap or even a block of wood, etc.

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Yeah, that’s a great idea @ok4450 . Last time I replaced my brake master cylinder, I saved the lid off the old one in anticipation of trying this idea out. My plan is to use the tire stem just like you describe. Glad to hear you have had luck with this. I haven’t tried it yet though. On early 70’s Ford trucks with drum brakes all around, brake bleeding isn’t much of a problem the old fashioned way.

OK, to update:

I disconnected the snap fitting between the fluid line and the MT. With the line automatically closed off, I stepped on the clutch…and got no resistance. (It should be noted that, prior to the bleeding procedure, the pedal was COMPLETELY IMMOBILE with the line disconnected.)

From this, I’ve drawn two possible hypotheses. In order of perceived likelihood:

  1. The bleeding procedure exceeded the usual range-of-motion of the (presumably tired) master cylinder, causing failure.

  2. The large pocket of air in the slave somehow migrated to the master, un-priming the pump, so to speak.

So, my plan going forward is:

  1. Bleed/replace master cylinder, as neccessary, until immobile pedal returns with line detached.

  2. Pressure bleed slave cylinder until clear fluid comes out transmission side of connector.

  3. Connect line: there should be functionality, at the least.

  4. Should clutch remain non-functional, hand job off to a pro (as I lack sufficient reserves of patience to redo this job and maintain sanity!)

Thanks for everyone’s help!