Help please: Bleeding Clutch Slave, Pedal won't come back up
05-01-2004, 11:37 PM
#1
Intermediate
Thread Starter
Join Date: Jan 2004
Location: Houston
Posts: 37
Likes: 0
Received 0 Likes
on
0 Posts
Help please: Bleeding Clutch Slave, Pedal won't come back up
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.
Any ideas as to what is the problem here. I am pretty sure I didn't introduce any air into the system.
05-02-2004, 01:18 AM
#3
Passed On
Rennlist Member
Rennlist Member
Don't use the "buddy-press-and-hold" method of bleeding. Go out and buy a pressure bleeder. My guess; I know from personal experience this old-fashioned bleed method will destroy brake master cylinders, so figure it's not the best for clutches either.
05-24-2005, 08:43 AM
#4
Rennlist Member
I posted this to the 993 board, but I had the same problem with my 944s.
For the 944 we used to raise the tail so that air would rise to the back of the slave cylinder and out the bleed nipple. Look at the cylinder's position and if needed, raise the car so that the bleed nipple end is higher.
For whatever reason, the clutch bleed is always a pain. Perhaps a pressure bleeder would help. That pushes the fluid into the system whereas a vacuum pump tries to pull it. The vacuum also pulls air into the bleed nipple via the threads. That is why I prefer pressure systems, but be careful!
You can manually pump it, but it is a physical workout. Unlike the brake system there is no danger in hyper-extending the pedal since it normally goes the full travel. I usually bleed it until there is no sign of air. Then I close the valve. Tie a rope to the pedal and use that to pull the pedal back. I stroke the pedal, pulling it back manually, until it "pumps up" to the normal pressure. The more you use it the better it gets. I don't know why, but I assume there is air in there somewhere that doesn't get pumped out when you bleed it, but works its way up when you stroke it. I would assume the air is actually at the master cylinder end.
The problem with hyper-extending the brake is that deposits can form on the inside cylinder and abrade the rubber seal of the piston as it strokes over it. That may be more myth than truth today. I would believe that if it was your grandfather's Chevy, but modern cars probably get better care and feeding and the likelihood of crud in the brake fluid is lower. Also, the cylinder may not be honed well or as deep as the full stroke, but again, newer car master cylinders are probably better made these days since tooling and machines are of higher precision.
Anyone care to comment on that?
Marv
For the 944 we used to raise the tail so that air would rise to the back of the slave cylinder and out the bleed nipple. Look at the cylinder's position and if needed, raise the car so that the bleed nipple end is higher.
For whatever reason, the clutch bleed is always a pain. Perhaps a pressure bleeder would help. That pushes the fluid into the system whereas a vacuum pump tries to pull it. The vacuum also pulls air into the bleed nipple via the threads. That is why I prefer pressure systems, but be careful!
You can manually pump it, but it is a physical workout. Unlike the brake system there is no danger in hyper-extending the pedal since it normally goes the full travel. I usually bleed it until there is no sign of air. Then I close the valve. Tie a rope to the pedal and use that to pull the pedal back. I stroke the pedal, pulling it back manually, until it "pumps up" to the normal pressure. The more you use it the better it gets. I don't know why, but I assume there is air in there somewhere that doesn't get pumped out when you bleed it, but works its way up when you stroke it. I would assume the air is actually at the master cylinder end.
The problem with hyper-extending the brake is that deposits can form on the inside cylinder and abrade the rubber seal of the piston as it strokes over it. That may be more myth than truth today. I would believe that if it was your grandfather's Chevy, but modern cars probably get better care and feeding and the likelihood of crud in the brake fluid is lower. Also, the cylinder may not be honed well or as deep as the full stroke, but again, newer car master cylinders are probably better made these days since tooling and machines are of higher precision.
Anyone care to comment on that?
Marv
05-24-2005, 11:11 AM
#5
Guru
Lifetime Rennlist
Member
Rennlist Small
Business Sponsor
Lifetime Rennlist
Member
Rennlist Small
Business Sponsor
I just replied to another thread. "What happened was you bled the clutch to the point where it sucked-in air from the reservoir. The clutch circuit doesnt take brake fluid from the bottom of the reservoir like the brake circuits do. So fill that sucker up and bleed your clutch again. Make sure you keep the fluid level in the reservoir really high to avoid sucking-in any more air. No worries!!"
Not positive the 944 has the same reservoir configuration, but since this is safety related, I wouldnt be surprised..
Not positive the 944 has the same reservoir configuration, but since this is safety related, I wouldnt be surprised..
