Slave cylinder leaking... again


J-Ri
05-28-2011, 11:14 PM
'04 Cavalier, manual transmission:

About a week ago I was driving and the clutch pedal started to get spongy and low. Thinking I was running out of fluid, I pulled into the next store that carried brake fluid. I checked the level, and it was full (to the very top). I was about 1/2 mile from work so I just kept going. The clutch pedal went to the floor and the clutch stayed engaged. I made it to work with the clutch stuck on.

I ordered a master cylinder and installed it at the end of my shift. I bled the system and the clutch then worked but the pedal was still low and spongy. I was in a hurry to get out of the shop before closing time, so I decided to drive it home like that. I made it a few blocks and the pedal went to the floor.

The next morning I tried bleeding it again, and vacuum bleeding did nothing, as it hadn't the night before. I was getting air out, but never got any fluid. I then tried manual bleeding (alone, relying on the double-spring mechanism to hold the pedal down while I opened the bleeder). I started to get a little bit of pedal, then heard what I soon learned was the sound of brake fluid runnig out from between the engine and transaxle.

So I ordered a slave cylinder. I installed it today, and vacuum bleeding did nothing, as it hadn't the week before. I was getting air out, but never got any fluid. I then tried manual bleeding (alone, relying on the double-spring mechanism to hold the pedal down while I opened the bleeder). I started to get a little bit of pedal (it actually got firm at the end of it's travel), then felt a slight pop in the pedal followed by the pedal going to the floor and the all too familiar sound of brake fluid splattering on the concrete.

What could be wrong? This doesn't make any sense to me. I'm an automotive technician (but we don't do intermal engine/transmission stuff where I work), and I don't know what could be wrong. I replaced the transaxle about a year ago (including swapping my slave cylinder/throwout bearing onto the salvaged transaxle). So I did the exact same thing I just did, only this time something went wrong.

As far as I could see, the clutch "springy finger dealeys" were good (once again, I don't do engine/trans/clutch work in a professional capacity, and have forgotten the name since school). None were broken/bent/missing and they were stiff enough that I could barely move one by hand. Prior to losing the clutch pedal, the clutch would hold up to a second gear burn-out with about 250 HP turning some grippy tires, so I doubt it's worn. The only time the clutch had ever slipped was when a friend bet me I couldn't spin the tires through all 5 gears on wet pavement (it started slipping as I dropped the clutch into 5th, and I let off the gas as soon as I saw the tach rise and the speedometer drop, maybe 1 second tops). It worked fine after that slippage and still held up to burnouts in second gear. I include that beacuse I remember reading that the clutch self-adjusts and at one point I was thinking maybe the slave cylinder had to travel too far and was pushing out of it's bore.

I'm installing a new engine next weekend or the week after, so I'd love an answer by then. Thanks in advance for any help!

EDIT: The slave cylinder I installed is a new AC Delco unit, I can get the part number if anyone thinks it's relevant, but I did compare the old and new ones side-by-side and they were visually identical

Blue Bowtie
05-30-2011, 11:43 AM
How does the pressure plate look? Throwout bearing? It's possible the slave is over-traveling, thereby admitting air. It's also possible that there is no air and the pressure plate is damaged.

J-Ri
05-31-2011, 04:37 AM
I'll have to pull the trans again to get a look at the pressure plate. All I looked at was the clutch diaphragm spring, and that was just poking at it while I was waiting for helpers to show up to help me lift the trans back into the car, not really inspecting it by any means. But nothing noticeably wrong there. I'm planning on trying to get it done tomorrow, but it's late (or early) now, probably wont get around to it until Wednesday. I work 2-10 PM, and I have 50 minutes of driving to get from home to where I'm working on my car and then I have to get a ride back to work and then home where my borrowed ride would be parked. :banghead:

The throwout bearing on these is part of the "clutch actuation cylinder" (which is what I referred to as the slave cylinder). The part contains both the throwout bearing and the slave cylinder. It is located around the trans input shaft, looks very much like this one from a Vauxhall, but the one for the Cavalier (Ecotec Getrag F23 anyway) has a plastic line built onto the back (part furthest away in image), which goes up and out through a hole in the bellhousing.
http://thumbs1.ebaystatic.com/m/moG4qGrev1UKEe9ee2uJ9hg/140.jpg

I was thinking there was air being pulled into the slave cylinder too, because the fluid was, if anything, higher than I would have filled it (definitely not low). I have seen brake calipers do that, so I assumed that's what happened here and I just replaced it without really looking at anything.

If the pressure plate were damaged, wouldn't the clutch slip? I drove about 100 miles slip-shifting and starting the engine in first gear since the clutch pedal went out (just to get home, then to where I was working on it, then back home because I planned on everything being good and didn't have any other way to get home). I didn't notice any slip then, but I went out just to test the clutch, and I could break the tires loose in second gear.

MT-2500
05-31-2011, 07:33 PM
I'll have to pull the trans again to get a look at the pressure plate. All I looked at was the clutch diaphragm spring, and that was just poking at it while I was waiting for helpers to show up to help me lift the trans back into the car, not really inspecting it by any means. But nothing noticeably wrong there. I'm planning on trying to get it done tomorrow, but it's late (or early) now, probably wont get around to it until Wednesday. I work 2-10 PM, and I have 50 minutes of driving to get from home to where I'm working on my car and then I have to get a ride back to work and then home where my borrowed ride would be parked. :banghead:

The throwout bearing on these is part of the "clutch actuation cylinder" (which is what I referred to as the slave cylinder). The part contains both the throwout bearing and the slave cylinder. It is located around the trans input shaft, looks very much like this one from a Vauxhall, but the one for the Cavalier (Ecotec Getrag F23 anyway) has a plastic line built onto the back (part furthest away in image), which goes up and out through a hole in the bellhousing.
http://thumbs1.ebaystatic.com/m/moG4qGrev1UKEe9ee2uJ9hg/140.jpg

I was thinking there was air being pulled into the slave cylinder too, because the fluid was, if anything, higher than I would have filled it (definitely not low). I have seen brake calipers do that, so I assumed that's what happened here and I just replaced it without really looking at anything.

If the pressure plate were damaged, wouldn't the clutch slip? I drove about 100 miles slip-shifting and starting the engine in first gear since the clutch pedal went out (just to get home, then to where I was working on it, then back home because I planned on everything being good and didn't have any other way to get home). I didn't notice any slip then, but I went out just to test the clutch, and I could break the tires loose in second gear.

Some they are just a pain to bleed out.

I always use a gravity bleed take top off master cylinder and crack open slay cylinder bleeder and just keep master cylinder full while it bleeds itself.

Also on some cars and trucks you have to unbolt master cylinder and tip it so the rear of master cyliner is below front.

Or jack up end of vechicle to get rear of cylinder below front.

J-Ri
06-01-2011, 01:22 AM
You're right, and this one is particularly difficult (probably in part because the end of the bleeder screw faces down). I did get it bled to where I had some pedal (and had done it twice before, once just to change the fluid, the other after replacing the transaxle), then fluid started gushing out from between the engine and trans. The clutch actuation cylinder is the only hydraulic part that is actually inside the bellhousing, so it is leaking, I just need to figure out why.

J-Ri
06-11-2011, 09:12 PM
The solution, if anyone else runs into this:

I finally got around to pulling the transaxle again, and found the problem. The clutch diaphragm spring was bent slightly (about 1/16" shorter than the new Exedy one). The clutch disc was just about flush with the rivets (as far as I know, it had 123,331 miles on it). The flywheel had 3 heat marks evenly spaced around the friction surface, I didn't measure them, but they seemed to make a nearly perfect equilateral triangle, the friction surface had a slight ridge where the clutch disc contacted it. So all in all, I'd say there was probably about 1/8" to 3/16" of wear that was allowing the slave cylinder to overextend. I replaced the flywheel, clutch disc, clutch cover, and slave cylinder. It drives like a new car, takes much less effort to change gears. It never seemed excessive, but now it just falls into every gear. I think the clutch diaphragm spring being bent was causing the clutch to not fully disengage.

MT-2500
06-12-2011, 05:55 AM
The solution, if anyone else runs into this:

I finally got around to pulling the transaxle again, and found the problem. The clutch diaphragm spring was bent slightly (about 1/16" shorter than the new Exedy one). The clutch disc was just about flush with the rivets (as far as I know, it had 123,331 miles on it). The flywheel had 3 heat marks evenly spaced around the friction surface, I didn't measure them, but they seemed to make a nearly perfect equilateral triangle, the friction surface had a slight ridge where the clutch disc contacted it. So all in all, I'd say there was probably about 1/8" to 3/16" of wear that was allowing the slave cylinder to overextend. I replaced the flywheel, clutch disc, clutch cover, and slave cylinder. It drives like a new car, takes much less effort to change gears. It never seemed excessive, but now it just falls into every gear. I think the clutch diaphragm spring being bent was causing the clutch to not fully disengage.

Thanks for posting back how it went.
Glad you got it fixed.
Good luck.

hoging
10-31-2011, 12:39 PM
hey i'm experiencing the same problem on my '02 cavalier. Did you buy a clutch kit with a slave cylinder or did you buy every part seperately ?

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