sdparks

I was bleeding the brakes on my 944 NA. Decided to bleed the clutch slave at the same time. Every time I depress the clutch pedal, I am getting some clean fluid out of the bleed valve. But the clutch pedal won't come back up.
Any ideas as to what is the problem here. I am pretty sure I didn't introduce any air into the system.

Bhj0887

If there is no air in the system the pedal would rise, if there's fluid coming out but no pressure at the pedal it sounds like the master cylinder. Looks like you need some new hydraulics.

But you can try the motive power bleeder first. Or if you don't want to buy it, rent it, steal it or use it, then you can jack up the passenger rear of the car and try bleeding it like that.

I'm assuming you have just the front end raised? Wrong way to do it, the fluid stays to the back of the resevoir away from the nipple thats goes to the master cylinder. Jacking up the rear passenger side will allow the fluid to flow to the master cylinder. I made the same mistake and so do most of the people who replace their master and slave cylinders.

Dave in Chicago

As stated, it's easy to catch a bit of air in the clutch hydraulics.

Here is a cure that has worked for me in the past...

Fill brake fluid reservoir
Place pan or reservoir below clutch slave
Open bleed valve until it just starts to drip (without a power bleeder)
Go and read the Sunday paper for about 30 minutes (no less)
Come back and close bleed screw (not much fluid will have come out)
Top off reservoir
If you have power bleeder, try it again here
If not, have an assistant help you with the conventional pedal bleed
Only open bleed DURING the downstroke of the pedal
Close screw at full pedal depth
Pull pedal back up if needed
Repeat until pedal returns.

If the hydraulics are in order, this usually allows the trapped air to find it's way out. Be patient with the gravity bleed process, it really is worse than watching paint dry.

Hope this helps. Has worked for me in the past.

Danno

The design of the fluid resevoir is truly stupid. There's a bulge at the front that traps an air-bubble when you have the resevoir topped of full of fluid. Then the hose for the clutch sucks in fluid near the top of the resevoir and it only takes 2-3 pumps before it sucks in that air-bubble. So you gotta raise the right-rear of the car by about 1-foot in the air so that you can get that air-bubble out. Then you can really top off the resevoir with fluid.

Then you'll need two people to bleed the clutch. One person opens the bleeder, the other steps on the pedal. Then the bleeder screw is closed, and the pedal is let up to suck in more fluid. Then you open the bleeder, pump the pedal, close the bleeder, up pedal, fill resevoir, etc. It also helps if the person pushing on the pedal does it quickly to get the air-bubbles out before they can rise up to the top again.

Bhj0887

You can do it with one person the conventional way. Jack the rear passenger side up, stick the end of the hose in a bottle 1/4 full of brake fluid, open the bleeder valve, depress the pedal, pull it up, keep doing it until it feels firm. I know for me it didn't return but you could feel the firmness. Close the valve, pump the pedal a couple more times and it will start to firm up and come off the floor, it will get firmer.

I did it this way and I have an excellent firm pedal feel.

houston944

We have tried everything suggested here, except for the power bleeder method. That's what we are going to try today.

In our first attempt, we did jack up the rear end of the car.

After reading through the replies, we tried gravity bleeding, followed by the two person bleeding. But the pedal still sinks to the floor. It is strange as to how we start getting all fluid out of the bleed valve and then all of a sudden we would get a bunch of air bubbles.

So we are going to try to find a power bleeder today and see if that makes any difference.

If that doesn't do it, how would we be able to tell, if it is the Slave cyclinder or the master cyclinder that has failed?

Scott at Team Harco

The obvious ways to tell will be fluid leaking around the boots of either the master or the slave. It sounds like you have clutch master problem if you have followed the slave cylinder bleed procedure as outlined above. Take a look up under the dash where the pushrod enters the clutch master. I'll bet it is wet.

Dave in Chicago

That's a drag. I did use the power bleeder after gravity bleed to solve my problem. Also, the power bleeder helps to understand if the system is maintaining pressure.

Dave (otherwise out of ideas) Swanson

Bhj0887

If it turns out you need a new master cylinder, buy the slave to or vice versa. The other one will crap out not too if you don't. If you do it yourself, you'll spend less thqan $150