Strange things while bleeding clutch

austin.schipper · 04-08-2012, 11:11 AM

So the clutch on my 91' 200 went out a while back. The master cylinder had been replaced recently so I assumed it was the slave. To make sure though I pumped the pedal a few times to make sure it was pushing fluid out of the line the feeds the slave. Yesterday I got a new slave cylinder installed and started working on bleeding it. I made a crappy little pressure bleeding setup which seemed to be working surprisingly well. It only holds pressure up to 5 psi so I wasn't worried about it damaging any seals.

So far I have spent about three hours and four pints of brake fluid bleeding. This seemed excessive but my pedal had pressure for about the last half of the throw by this point. Then I got a massive bubble coming out. At first I thought great this should be most of what is left in the system. But fluid just stopped coming out. When I went back and tried the pedal it sprung all the way down to the floor, no pressure at all. I tried for about another hour to get fluid through the system but neither my pressure bleeder or pumping the pedal is doing anything. It sounds like the master is empty when I move the pedal up and down.

The reservoir never went dry. I'm at a loss as to where all the air came from. Could the seals on my master have gone out? And if this is the case why isn't the pressure bleeder pushing fluid through anymore?

yodasfro · 04-08-2012, 10:44 PM

There is the possibility that when you installed the slave the end of the piston push rod didn't get seated in the dish on the throw out bearing lever. It does require quite a bit of force to get the slave installed correctly. This tends to happen more with aftermarket slave cylinders such as FTE brand because the push rod isn't held tight in the piston like on the sachs slave. So it tends to flop around making it harder to get things lined up. If it was easy or almost too easy to get the slave seated it's worth pulling it out to try again. You'll need to undo the hose though otherwise it will be near impossible to get it seated again.

RussB · 04-09-2012, 02:45 AM

I spent hours bleeding my clutch and eventually replaced both the slave and master cylinders, and still it wouldn't thoroughly bleed. Eventually I replaced the hose, and all bleed problems disappeared. YMMV.

Kneale Brownson · 04-09-2012, 04:48 AM

IF you can get someone to pump the clutch while you watch the hose, you may see it bulging or seeping.

austin.schipper · 04-09-2012, 06:47 PM

Cool thanks guys. WIth the amount of air I was getting out of the bleed valve I was starting to wonder about the lines being an issue. But this weekend when I have time Ill pull the slave out again. There definitely was some slop in the piston and I can see how it might have missed the dimple in the throw out bearing lever.

pureroundcircle · 06-12-2012, 10:15 PM

Bleed it backwords. Use a pressure oiler bottle like the $3 one harbor freight sells, open the bleeder on the slave and pump it in backwords through the bleeder screw. It works VERY well for the 5000's and the last 200 I've had.

Here is the bottle I'm talking about: http://www.harborfreight.com/8-oz-hi...ler-66350.html

they have an even cheaper version in the store.

88A5TQ · 06-14-2012, 04:54 AM

When I bled my 5000's clutch I had the same issues. I used a cheap brake bleeder and a nice amount of teflon tape on the bleed screw. Just do it the traditional way with a helper to work the pedal and you bleeding the system while closing screw before they pull the pedal back up. Bleed screw threads, even new, can suck air into the sytem. Good luck.

04-08-2012, 10:44 PM	#2
yodasfro AudiWorld Super User Garage is empty, add now Join Date: Mar 2005 Location: CT Posts: 2,392	There is the possibility that when you installed the slave the end of the piston push rod didn't get seated in the dish on the throw out bearing lever. It does require quite a bit of force to get the slave installed correctly. This tends to happen more with aftermarket slave cylinders such as FTE brand because the push rod isn't held tight in the piston like on the sachs slave. So it tends to flop around making it harder to get things lined up. If it was easy or almost too easy to get the slave seated it's worth pulling it out to try again. You'll need to undo the hose though otherwise it will be near impossible to get it seated again. __________________ Austin 92 urs4 91 200 20v 90 90q 20v 88 5ktq avant Last edited by yodasfro; 04-08-2012 at 10:47 PM.

04-09-2012, 02:45 AM	#3
RussB AudiWorld Super User Garage is empty, add now Join Date: Jan 2003 Location: Fort Lauderdale, Florida Posts: 2,643	I spent hours bleeding my clutch and eventually replaced both the slave and master cylinders, and still it wouldn't thoroughly bleed. Eventually I replaced the hose, and all bleed problems disappeared. YMMV. __________________ Russ Bellew 1988 5000CS Turbo Quattro My blog http://russbellew.com

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04-09-2012, 04:48 AM	#4
Kneale Brownson AudiWorld Super User Garage is empty, add now Join Date: Apr 2003 Location: Full-time Coloradoan now Posts: 3,341	IF you can get someone to pump the clutch while you watch the hose, you may see it bulging or seeping.

04-09-2012, 06:47 PM	#5
austin.schipper Audiworld Junior Member Garage is empty, add now Join Date: Nov 2007 Posts: 21	Cool thanks guys. WIth the amount of air I was getting out of the bleed valve I was starting to wonder about the lines being an issue. But this weekend when I have time Ill pull the slave out again. There definitely was some slop in the piston and I can see how it might have missed the dimple in the throw out bearing lever.

06-12-2012, 10:15 PM	#6
pureroundcircle AudiWorld Member Garage is empty, add now Join Date: Oct 2004 Posts: 535	Bleed it backwords. Use a pressure oiler bottle like the $3 one harbor freight sells, open the bleeder on the slave and pump it in backwords through the bleeder screw. It works VERY well for the 5000's and the last 200 I've had. Here is the bottle I'm talking about: http://www.harborfreight.com/8-oz-hi...ler-66350.html they have an even cheaper version in the store.

06-14-2012, 04:54 AM	#7
88A5TQ Audiworld Junior Member 1988 Audi 5000 Join Date: Sep 2009 Posts: 43	When I bled my 5000's clutch I had the same issues. I used a cheap brake bleeder and a nice amount of teflon tape on the bleed screw. Just do it the traditional way with a helper to work the pedal and you bleeding the system while closing screw before they pull the pedal back up. Bleed screw threads, even new, can suck air into the sytem. Good luck.