Tips for bleeding hydraulic clutch?
 

I am putting a 460 with ZF 5-speed in my F150 and one of the things I am running up against is bleeding the hydraulic clutch. This has the external slave cylinder. On the previous setup, with the internal slave, you just gravity bled it a bit and you were good to go. Not so on this one, the fluid barely comes out, like 1 drip every 10 minutes. I have tried bleeding it like you do brakes, with one person pumping the pedal and then releasing the bleeder, this did make it better, but it still has quite a bit of free travel at the top.

I looked up the procedure in my Ford manual and it says to disassemble the whole apparatus and then fill the slave with fluid and reassemble. What the heck is the bleeder screw for, then?

Anyone done this successfully? I have never had to pressure bleed a hydraulic clutch before, they usually just gravity bleed. Should I use a vacuum pump? TIA for any help.

I would say go buy one of of those hand bleeders from the lps. I used one and it worked like a dream and it's good for other applications

https://www.ford-trucks.com/forums/5...-a-clutch.html Some ideas for you in this thread.

Thanks, Lazy K, I admit I did not do a search first before posting. I think I have enough clutch to drive it, I guess I will try the bumpy road approach first since that is pretty easy.

my truck sat for a while and the clutch would en-gauge so i ask my dads buddy who owned a garage in his younger days and he said pump it 50 times with one leg and another 50 times with the other and it should work so i tried it and it did....

For my mazda transmission, I used a vacuum pump with a cup inline of the suction line. Vacuum pumps can be pretty handy to have around, I use mine for stubborn brake lines that I just can't get the air out of with a gravity bleed and it works pretty well.

If you have air in the master cylinder, with the bleeder closed, if you pump the clutch pedal up it should help get air out. You may have to do this for a while. In my experience with automotive hydraulic systems, when there is no fluid coming out of the bleeder there is probably a large amount of air in the system. As you get the bulk of the air out, the fluid should flow pretty steadily when the bleeder is open.

I have read that the easiest way to bleed the external slave is to take it off of the engine, hold it with the hose-end up and move the slave piston by hand through the full stroke a few times.

That's what the Ford manual says but getting that little roll pin out so you can release the line is a PITA. I can't see how taking the thing apart is not going to introduce more air to the system, tho.

When you push the clutch in, the bleeder should be open, when you let it out, it should be closed. it should take two people to do it.

Leave the hydraulic line connected during the process. Like you said, it really won't do any good if you have to open the system again after bleeding.

I just bled my 96 zf5 clutch. I simply loosened the bleed screw on the slave and had someone else press the clutch slowly, closed the valve, and repeated several times. This was all done with the master and slave installed on the truck. I used a torx t25 to loosen the bleed screw, although I'm pretty sure it's actually an Allen. The clutch went from completely non-functional to working properly in 15 minutes. If some slaves do not have bleed screws, I don't know what to do then, lol.

After draining clean fluid through the system, close the bleed screw, jack up the front of the truck and pump the pedal up and down as fast as you can by hand. The clutch master must be tilted slightly up to bleed correctly. You might have to pump the pedal 40 or 50 times. Push the pedal down and pull it up quickly over and over.

You are correct, I am the OP on this thread and I have found the most effective method is to park the truck on a steep hill on my property and pump the pedal about 20 times, let it sit for a few hours, do it again, and repeat as needed. This has worked every time so far.