the pedal gets stuck in the down position. Because of that and some other reasons the car is not drivable at the moment.

I tried heavy grease around the bleeder valve and tried vacuum bleeding again but I am getting very little fluid out.

 

When replacing the hydraulic line from the clutch mc to the clutch slave cylinder, was the hose from the brake master cylinder to the clutch mc moved, removed, wiggled, etc.?

Tne clutch hydraulic fluid supply nipple connection at the brake mc can develop a crack at the reservoir interface. There is no fluid leak but using the vacuum bleeder would create a vacuum to draw air thru the crack into the supply hose. I had this nipple crack open on my brake mc reservoir, race car.

 

Another trick is to push the clutch slave piston in and out manually.

If you are not getting any fluid out maybe the reservoir is low? The clutch feed is higher up on it. With the car not level it's easy to run too low on brake fluid and get air in the clutch line, had this problem myself.

 

As a final sanity check, you could try the reverse bleed up through the blue hose, with the blue hose disconnected from the reservoir. This would involve a creative assortment of caps for the various attachment points, but you could see if you have a problem with the hose itself.

Cheers

 

Interesting. It was not directly moved, but I did some work in that area. Any way to check?

 

You mean disconnect the blue hose and then push fluid from the slave up?

 

With all the parts in good condition, bleeding with a pressure bleeder (ie Motive) won't result in "pedal stays down"... maybe a soft pedal but not a total failure

I suspect some part(s) is no longer in good condition

 

@944tger : Correct, that is what I'm suggesting as a troubleshooting attempt, to see if there's any issue in either that line, or the slave cylinder.

Now that Dan has chimed in, it reminds me to ask if you inspected your clutch fork. Those can cause some heartache.

Cheers

 

When my fork was cracked, clutch didn't fully release... can't imagine how it would cause a pedal to stay down though.

Incorrectly installed spring on pedal... bad slave or master... leak in a line...

 

Thanks again for the new replies! Today I removed the master cylinder to inspect it. Seems to be older than the slave cylinder the the look of it, the blue hose was definitely due for a refresh.

After removal I put the blue hose in a container of brake fluid and did some pumping of the pedal arm(?). I could get a contestant flow/splash out of the outlet of the cylinder. Not sure if that says anything definite but I have a new one on order just in case.

I have one more question about installing the new one. I read here in a few threads that bench bleeding the new master is advisable. I checked a few YouTube videos on that, but all the master cylinders shown had their own reservoir. Logistically, how do you "bench" bleed the master cylinder of a 944 before installing it?

 

I made some progress today, but have not succeeded yet. I realised one mistake I did was not removing the plastic insert from the reservoir. The reservoir always looked full, but there was air pulled in on the inside into the blue hose. After I removed it all filled it up to the edge I was able to bleed the system all the way to the hard line that goes into the slave cylinder by using my vacuum bleeder. But as soon as I reconnect the hardline and try to bleed it through the bleed nipple of the slave cylinder I am getting a constant stream of air bubbles… where is this air coming from?? I put heavy grease on the bleed nipple already, from where can the slave pull air? Any ideas?

 

Now if the hose on the nipple is not tight you can pull air in and it looks like it is coming out of the cylinder. That is with the vacuum system, when I changed my clutch last year and put in a remanufactured slave cylinder with the Speed Bleeder and pumped the pedal about five times closed the bleeder and that was all it took. That way you are using pressure and not vacuum to bleed the system.

 

I guess you are right. I bought a pressure bleeder and tried bleeding again. Got a few more bubbles out of the slave and now the clutch is alive again! Should have gotten that one instead of the vacuum bleeder in the first place.

I am unsure about the clutch pedal adjustment, pedal feels about strange still but I guess I can only fully test when the car is running again.