replaced clutch master/slave and can't get air out of line...help!

[veleno]

Car is a '90 S2

So I've replaced the clutch master, slave, blue hose, and hard like between master/slave. I used a Motive brake bleeder, raised the rear and bled the system with very little success.

I then raised the rear even higher, tried again, made sure the reservoir never got empty, and put between 5-10 lbs. of pressure on the reservoir and still no luck. Tried it with the pedal, got some pressure back to the pedal but still no luck.

The pedal continues to stay on the floor.

I can shift fine if I "eagle claw" the pedal up with my toes but damn that's not the way I want to drive around!

Any ideas what I can do to get the air out? I'm about to turn it in to the mechanic so he can give it a try...

[John_AZ]

You may have an air pocket in the clutch hose you replaced (on your 88 944).

At the connector on the fire wall, pack cloths around the hose connector and with light pressure on the Motive brake bleeder, open the connection until fluid comes out.

OR, unbolt the slave from the bell housing, hose still attached --pull out slightly and try to bleed again with the Motive ---bolt up slave and test.

GL
J_AZ

[veleno]

Hi John,

Sorry, I forgot to mention that this is on my '90 S2 cab.

Which specific connector are you referring to at the fire wall? Are you talking about the blue hose that connects to the clutch master, or are you talking about the hard line that connects to the front of the clutch master? Are you saying I might have air in the clutch master?

As for unbolting the slave from the bell housing and bleeding it, what exactly does this do and how is it different from leaving it bolted and bleeding it (like I've been doing)?

Sorry for the questions, I'm still learning

Thanks for the help.

[John_AZ]

Look at figure 21 on the Tech article to see the connector:

Pelican Technical Article: Porsche 944 Clutch Master and Slave Cylinder Replacement

Removing the clutch slave from the bell housing because there may be pressure on the slave piston to the clutch fork causing an air bubble.

Just ideas.

J_AZ

[veleno]

Thanks John. I'll try the connector (it's in a different location on my S2) and see how that goes as that's the easiest to do.

[mikepellegrini]

If there's air left in the master cylinder, you'd wanna raise the front of the car.

Plus, watch that you're not sucking air in the intake line from the reservoir. It's awfully high up on the reservoir.

[Capt Squid]

Another method is to attach a piece of vinyl tubing to the left front caliper bleed screw and to the clutch slave bleeder screw. Wrap a rag around both and start pumping the brake pedal. Works like a champ to push the air bubbles up to the reservoir.

[Gawernator]

+1

[veleno]

Originally Posted by Capt Squid

Another method is to attach a piece of vinyl tubing to the left front caliper bleed screw and to the clutch slave bleeder screw. Wrap a rag around both and start pumping the brake pedal. Works like a champ to push the air bubbles up to the reservoir.

Sounds like a good plan, but I'd have to bleed the brakes first as I used better fluid and want to get the old one out first.

[flash968]

since you replaced the parts with all new parts (not rebuilt or DIY rebuilt) i would tend to say that these are not the issues.

since they share the same reservoir, and any contaminates there would make their way to the reservoir, bleed and flush the brakes first.

try 10lbs of pressure, with fluid in the motive as instructed. work from the right rear wheel first, then to the left rear, then the front right, then the left right.

then move on to the slave.

[rhett]

Originally Posted by Capt Squid

Another method is to attach a piece of vinyl tubing to the left front caliper bleed screw and to the clutch slave bleeder screw. Wrap a rag around both and start pumping the brake pedal. Works like a champ to push the air bubbles up to the reservoir.

That's why I like this forum - I would not have thought of that technique! The only thing I would do is ensure the caliper I was using had been bleed (to get the crud out) as I would not want to push that into the clutch hydraulics. Otherwise...

[88Silver924S]

I had the same problem & I rigged up the pressure port of my Mighty Vac to a cup of brake fluid to "push" brake fluid from the slave up to the reservoir. It was a time consuming pain but it did get the last little bubble out. The thinking is that the air bubble wants to go up and out, not down and out.

[DSDoug]

The passageway from the main master reservoir to the clutch section of the reservoir is very small. Fast bleeding can lower it's level allowing air to enter the clutch master. Try raising passenger side to force better flow. But really, pressure bleeding from the slave sounds like the best idea....wish I had thought of that!