Wasted a portion of my afternoon trying to bleed my New NAPA slave today. I tried it with the slave mounted on the bellhousing. It was still spitting air when I knocked off to eat dinner. Bleeder is on the bottom of the slave so I believe I have a air pocket in the slave. I have no pedal right now.

Put the wifee in the car pushing in the pedal and also tried a Mityvac. Neither was successful.

I am opening it up for tips and suggestions.

I used a mityvac, too, to draw the fluid down with. It took a couple of shots with fluid, then, be sure the bleed is tight and you should have pedal.

When I replaced my clutch Master cylinder and slave, I had my neighbor in the car and I was under and all came out well. Good hard pedal. I keep hearing it can;t be done but lucky I guess!

the ZF hyrdaulics are really tempermental. I think I got lucky the last time I did it...

I know zero about a ZF clutch, but I've used pressure bleeding on brake systems that are known to be a PITA and it makes them a breeze.

Example:

A phoenix tool would probably be the most surefire way.

How much room is in your engine bay? On my 85 I was able to bleed the system comfortably with the slave up next to the master, then snake it through with the line attached and install it.

Quote:

When it came to the bleeding part, me too, I guess. Here's my experience:

http://www.corvette-guru.com/modules/ ... id=112261#forumpost112261

If you don't want to read through the entire thread, here's the pertinent part:

"..As for bleeding, no problem there either. Didn't pre-bleed it before installing, just an initial gravity bleed, about ten minutes of me in the car on the lift pumping the clutch and the tech underneath working the bleeder valve (and occasionally getting on a step ladder to top off the reservoir) and the job was done..."

If you have a mighty vac, you can do it yourself. I've done 25 or more ZF hydraulic systems in this manner and never had an issue:

One hose on the mighty vac sucks, the other blows. Open the bleeder on the slave and attach the blowing hose to the bleeder. Stick the sucker end of the mighty vac in your brake/clutch fluid. Slowly pump the mighty vac.

You'll fill the system through the bleeder screw from the bottom up. The air wants to go to the top, trying to bleed it out the bottom makes no sense, why GM designed it that way is beyond me. It would be almost impossible to force an air bubble out the bottom of the slave.

If necessary, you can unbolt the slave and hold it in such a manner as to make the steel inlet tube the highest point. That way, as you pump fluid in the bleeder valve, all the air goes up and out the line.

Have someone watch the master so you don't over fill it and dump fluid all over everything. There's no need to pump the clutch to move the master or anything, the system will fill properly with no movement of the master cylinder.

Hopefully, that makes sense. If not, let me know and I'll try again.

Also, it might not be worth it to you, but taking the slave apart and checking a few things is a good idea. You can check to make sure the seal is installed the right way. If you've done any reading on the hydraulic issues we have, you know that a good portion of the slaves out there had the seal installed backwards.

I've lost track of how many slave/master/clutch jobs I've done on various ZF6 C4's in the last few years, but it's more than 20. Out of all those slave cylinders, not one of them was clean inside the bore. There was always crap laying in the bore, just waiting to damage the seal.

I like to check the seal orientation, and clean the bore when I get a new slave. For awhile I was installing 2 star washers to hold the boot in place, but I kinda quit doing that. I check the masters as well, but they are much less problematic. Some of them still have the dirty bore, but it's more like 40% as opposed to the 100% rate the slave cylinders have.

Chances are you'll be fine without doing any of that, but I thought I would throw it out there.

[quote]
Josh wrote:

If necessary, you can unbolt the slave and hold it in such a manner as to make the steel inlet tube the highest point. That way, as you pump fluid in the bleeder valve, all the air goes up and out the line.
quote]



I agree, you have to turn the thing upside down to get all the air out of it. Why didn't GM put the bleeder on the top?