Clutch Hydraulic problem
Thread Starter
Burning Brakes
Joined: May 1999
Posts: 1,189
Likes: 0
From: Lewisville Texas
Cruise-In II Veteran
Clutch Hydraulic problem
OK, I just blead this clutch (for the last 5 hours 
) and it's still not working. I took the slave off and bench blead it...didn't work. Opened the bleader valve and blead it the old fashioned way...still nothing. I can get it blead but when I put it all back together and step on the clutch there is very little pressure. After bleading everything if I pump the slave cylinder from the bottom it will bubble at the top. I've tried everything but this still bubbles when I'm done and won't move enough to disengage the clutch. The reason for this clutch blead is about 3 weeks ago I went to put the car in gear and it wouldn't go so I opened the resovouir and it was empty so now I'm fairly confidant that I have a parts failure...but which part? The slave or the master??? If anyone can think of something I'm missing before I throw money at this I'm open for suggestions. Otherwise, which part is more prone to fail or which one would you start with?
) and it's still not working. I took the slave off and bench blead it...didn't work. Opened the bleader valve and blead it the old fashioned way...still nothing. I can get it blead but when I put it all back together and step on the clutch there is very little pressure. After bleading everything if I pump the slave cylinder from the bottom it will bubble at the top. I've tried everything but this still bubbles when I'm done and won't move enough to disengage the clutch. The reason for this clutch blead is about 3 weeks ago I went to put the car in gear and it wouldn't go so I opened the resovouir and it was empty so now I'm fairly confidant that I have a parts failure...but which part? The slave or the master??? If anyone can think of something I'm missing before I throw money at this I'm open for suggestions. Otherwise, which part is more prone to fail or which one would you start with?
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
how old are the parts?
I know GM has had a big problem with slaves... more than masters.
I would start with trying a Pheonix tool. It will pump fluid up from the bottom. This way you know the system is bled.
If I had to guess? slave is done. It will blow it's seals internally, blowing pressure into the outside chamber... but if the outer seal is good, you will never see it.
I know GM has had a big problem with slaves... more than masters.
I would start with trying a Pheonix tool. It will pump fluid up from the bottom. This way you know the system is bled.
If I had to guess? slave is done. It will blow it's seals internally, blowing pressure into the outside chamber... but if the outer seal is good, you will never see it.
Team Owner
Joined: Aug 2000
Posts: 40,156
Likes: 45
From: San Pedro CA
Originally Posted by vetster86
Gm sells it as a package, master, slave & a bag of oil together for about $165.00 for LT1's not sure for the L98's 
Racer
Joined: May 2004
Posts: 476
Likes: 0
From: DFW TX
Originally Posted by bogus
you don't wanna do that... GM has been having issue with these kits for some time.
Team Owner
Joined: Dec 1999
Posts: 34,873
Likes: 487
From: Lacey WA RVN 68-69
NCM Sinkhole Donor
There's always a chance that some old GM units would be sitting on a shelf and you could get one of the old ones. There are rebuild kits but if the piston is scarred or pitted, the kits won't really do a lot of good.
I would replace the slave cylinder first (NAPA should have one that is cheaper than the GM unit), but you mentioned that the master reservoir was emptied at one point. That fluid had to go somewhere. Do you see any areas being wet with fluid? Is the hose dry?
Hoses will go bad and expand internally under pressure or even spring a leak. The hose is no longer available from GM and according to Scorp, the replacement hose in Ecklers doesn't really fit right without bending. Any good hydraulic hose shop can make another one using the original metal fittings.
Another possibility (but fairly remote) is a worn-out or broken stud that the throwout arm sits on or even a throwout bearing.
I would replace the slave cylinder first (NAPA should have one that is cheaper than the GM unit), but you mentioned that the master reservoir was emptied at one point. That fluid had to go somewhere. Do you see any areas being wet with fluid? Is the hose dry?
Hoses will go bad and expand internally under pressure or even spring a leak. The hose is no longer available from GM and according to Scorp, the replacement hose in Ecklers doesn't really fit right without bending. Any good hydraulic hose shop can make another one using the original metal fittings.
Another possibility (but fairly remote) is a worn-out or broken stud that the throwout arm sits on or even a throwout bearing.
Racer
Joined: May 2004
Posts: 476
Likes: 0
From: DFW TX
Originally Posted by c4cruiser
There's always a chance that some old GM units would be sitting on a shelf and you could get one of the old ones. There are rebuild kits but if the piston is scarred or pitted, the kits won't really do a lot of good.
I would replace the slave cylinder first (NAPA should have one that is cheaper than the GM unit), but you mentioned that the master reservoir was emptied at one point. That fluid had to go somewhere. Do you see any areas being wet with fluid? Is the hose dry?
Hoses will go bad and expand internally under pressure or even spring a leak. The hose is no longer available from GM and according to Scorp, the replacement hose in Ecklers doesn't really fit right without bending. Any good hydraulic hose shop can make another one using the original metal fittings.
Another possibility (but fairly remote) is a worn-out or broken stud that the throwout arm sits on or even a throwout bearing.
I would replace the slave cylinder first (NAPA should have one that is cheaper than the GM unit), but you mentioned that the master reservoir was emptied at one point. That fluid had to go somewhere. Do you see any areas being wet with fluid? Is the hose dry?
Hoses will go bad and expand internally under pressure or even spring a leak. The hose is no longer available from GM and according to Scorp, the replacement hose in Ecklers doesn't really fit right without bending. Any good hydraulic hose shop can make another one using the original metal fittings.
Another possibility (but fairly remote) is a worn-out or broken stud that the throwout arm sits on or even a throwout bearing.
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Melting Slicks
Joined: May 2002
Posts: 2,670
Likes: 4
From: Severna Park MD
My clutch hydraulics has had a slow leak for the last year. It became a gusher last month, leaving a puddle on the garage floor. Just yesterday I had to add fluid to get the car out of my garage.
Three years and 30000 miles ago I had both master and slave replaced, hoping to be done with the problem. I'm sure it's the slave this time as that's where the puddle is forming.
So the real question is, do I try the GM part again or do I buy the part elsewhere? Would it make any difference in trying to get a replacement part that is not from the bad batch?
One important thing here, after I fill my reservoir and pump the pedal a few times the clutch acts normally. Until it gets low again. In your case, since you can't get any hydraulic pressure after filling the problem might be in the master cylinder.
Three years and 30000 miles ago I had both master and slave replaced, hoping to be done with the problem. I'm sure it's the slave this time as that's where the puddle is forming.
So the real question is, do I try the GM part again or do I buy the part elsewhere? Would it make any difference in trying to get a replacement part that is not from the bad batch?
One important thing here, after I fill my reservoir and pump the pedal a few times the clutch acts normally. Until it gets low again. In your case, since you can't get any hydraulic pressure after filling the problem might be in the master cylinder.
Last edited by FELNGR8; Jan 16, 2005 at 11:09 AM.
Thread Starter
Burning Brakes
Joined: May 1999
Posts: 1,189
Likes: 0
From: Lewisville Texas
Cruise-In II Veteran
For $165 it might be worth it to replace both. Doing a quick search online and the best I can find them for is $109 each. If it's teh hose I might have to try the junkyard since they don't make them anymore, but I will replace the other parts first to see if that answers the question.
Also someone asked if I had seen any puddles, No I haven't. Since the fluid does have to go somewhere that has me a little worried in case it drained into the clutch housing, but I don't know if that would be a major problem.
Also someone asked if I had seen any puddles, No I haven't. Since the fluid does have to go somewhere that has me a little worried in case it drained into the clutch housing, but I don't know if that would be a major problem.
Safety Car
Joined: Feb 2001
Posts: 4,397
Likes: 0
From: Looks like I picked the wrong week to stop sniffin glue Orlando
First and foremost, make sure you actually have a leak. If you filled the reservoir and bleed the system correctly than that fluid has to be going somewhere. Either down the inside or outside of the firewall, the hydraulic line itself, or at the slave cylinder.
If you cant find any wet spots than you don’t have a leak.
As for bleeding the clutch system. It’s even simpler than the brakes.
I’ve never bench bleed anything and have always got it right the first time.
Assemble the system and fill the reservoir with fluid. Leave the slave detached from the bell housing, hold the slave in such a manner that the hydraulic hose is at the highest point.
Actuate the slave plunger with your thumb. The first few strokes will just pull in fluid to fill the empty void of the slave.
Now here’s the key. When you depress the plunger and the air bubbles rise up into the reservoir hold the slave plunger in the depressed state for at least 30 seconds.
This allows the air bubbles to rise and escape from the reservoir.
If you just depress the plunger and then let it go without waiting it will pull the air bubbles right back into the slave.
I can do this job sitting next to the front tire reaching under the car, and still be able to look into the clutch master reservoir to see the bubbles.
If you cant find any wet spots than you don’t have a leak.
As for bleeding the clutch system. It’s even simpler than the brakes.
I’ve never bench bleed anything and have always got it right the first time.
Assemble the system and fill the reservoir with fluid. Leave the slave detached from the bell housing, hold the slave in such a manner that the hydraulic hose is at the highest point.
Actuate the slave plunger with your thumb. The first few strokes will just pull in fluid to fill the empty void of the slave.
Now here’s the key. When you depress the plunger and the air bubbles rise up into the reservoir hold the slave plunger in the depressed state for at least 30 seconds.
This allows the air bubbles to rise and escape from the reservoir.
If you just depress the plunger and then let it go without waiting it will pull the air bubbles right back into the slave.
I can do this job sitting next to the front tire reaching under the car, and still be able to look into the clutch master reservoir to see the bubbles.
Le Mans Master
Joined: Feb 2000
Posts: 9,600
Likes: 88
From: Springfield PA
Philly 'Burbs Events Coordinator
GM's issue with the slaves was due to poor tolerances from their vendor. The vendor has been replaced, all old stock was supossed to be removed. If you a new GM slave it should have no white or yellow marks on the slave itself. Marks indicate the vendor who had tolerance problems. I just put #4 in today.
Intermediate
Joined: Mar 2005
Posts: 47
Likes: 0
Im getting ready to replace the master cylinder either tuesday or wednesday. I have fluid on the inside of the fire wall. My question is will I have to bleed the system at the slave or can I do it somewhere else. And also is the slave on the outside of the bell housing. I have a 96 LT-4 with the ZF if that makes any difference. Thanks for any extra help before I do this.
Le Mans Master
Joined: Feb 2000
Posts: 9,600
Likes: 88
From: Springfield PA
Philly 'Burbs Events Coordinator
Originally Posted by Rane LT4
Im getting ready to replace the master cylinder either tuesday or wednesday. I have fluid on the inside of the fire wall. My question is will I have to bleed the system at the slave or can I do it somewhere else. And also is the slave on the outside of the bell housing. I have a 96 LT-4 with the ZF if that makes any difference. Thanks for any extra help before I do this.
Race Director
Joined: Aug 2002
Posts: 16,024
Likes: 0
From: Stratford Ontario
If your slave is in good working order it will self bleed. You do not need to remove it or mess with the bleeder valve.
Once you get the master changed, fill it up and with the car on level ground slowly depress the clutch pedal and you will see bubbles rising from the line. Do this until you have a firm pedal and no bubbles.
The hardest part about this job will be contorting yourself to disconnect the retainer clip on the clutch pedal. The rest is very straight forward.
Once you get the master changed, fill it up and with the car on level ground slowly depress the clutch pedal and you will see bubbles rising from the line. Do this until you have a firm pedal and no bubbles.
The hardest part about this job will be contorting yourself to disconnect the retainer clip on the clutch pedal. The rest is very straight forward.
Instructor
Joined: Feb 2000
Posts: 195
Likes: 0
From: Woodbridge VA
The first time I changed my clutch I had the same problem (i.e., no pressure at the pedal). We kept bleeding at the slave, but it never changed. A GM tech told me to bleed it at master cylinder from the hose line with it all in the car. After bleeding at the master about 5 times, the clutch finally came in. Sounds like this could be your problem; still too much air at the master.
ZZZASY
'96 LT4
ZZZASY
'96 LT4
