Clutch Issue? Need advice!
Thread Starter
Drifting
Joined: May 2007
Posts: 1,426
Likes: 165
From: Motor City
Clutch Issue? Need advice!
Well it seems that the years of neglected maintenance on my dads 93 corvette is catching up. I recently did a water pump and plugs on it due to a leaking weep hole. Come to find out the plugs and wires have never been replaced and i imagine nothing else has either. The car has 76k.
I took it out to inspect the new water pump and make sure there are no leaks (everything looks good
) but when in neutral it and the clutch out with the engine running it is making an intermittent clunk type noise and goes away when the clutch is pressed in. Is this the throw out bearing going bad? It seems to shift fine and i made sure the fluid was topped in the trans.
This is the bad part. I read some stuff on zfdoc.com and found out that proper maintenance to the clutch is very necessary as i would assume. I pulled the brake fluid cap yesterday and realized the fluid is BLACK, like really black. I would not be surprised if it has never been changed.
So, my question is the noise the throw out bearing? Will new fluid possibly solve the problem?
I want to know what im getting into here. Thanks
I took it out to inspect the new water pump and make sure there are no leaks (everything looks good
) but when in neutral it and the clutch out with the engine running it is making an intermittent clunk type noise and goes away when the clutch is pressed in. Is this the throw out bearing going bad? It seems to shift fine and i made sure the fluid was topped in the trans. This is the bad part. I read some stuff on zfdoc.com and found out that proper maintenance to the clutch is very necessary as i would assume. I pulled the brake fluid cap yesterday and realized the fluid is BLACK, like really black. I would not be surprised if it has never been changed.
So, my question is the noise the throw out bearing? Will new fluid possibly solve the problem?
I want to know what im getting into here. Thanks
Racer
Joined: Aug 2009
Posts: 274
Likes: 0
From: lexington NC
It's hard to say, Ive never seen old fluid make any noise, but Ive never seen black fluid.
My advice. Check your slave cyl. make sure it is working right. try and adjust in some and see if that helps any. If it dont help, remove the slave cyl and get a flash light and see if you see any metal debris. It could be the throw out bearing.
now thats my "Im broke guess and check" This what you should do.
change the fluid!!, It cant hurt and it soulds like it needs done anyway. Replace the slave cyl with a new one. As slave cyls get old they start holding pressure on the throw out bearing, Or not hold enough. And leak fluid around the seals, regaurdless with the fluid so old its black, I would say its not in real good shape to begain with.
My advice. Check your slave cyl. make sure it is working right. try and adjust in some and see if that helps any. If it dont help, remove the slave cyl and get a flash light and see if you see any metal debris. It could be the throw out bearing.
now thats my "Im broke guess and check" This what you should do.
change the fluid!!, It cant hurt and it soulds like it needs done anyway. Replace the slave cyl with a new one. As slave cyls get old they start holding pressure on the throw out bearing, Or not hold enough. And leak fluid around the seals, regaurdless with the fluid so old its black, I would say its not in real good shape to begain with.
Thread Starter
Drifting
Joined: May 2007
Posts: 1,426
Likes: 165
From: Motor City
It's hard to say, Ive never seen old fluid make any noise, but Ive never seen black fluid.
My advice. Check your slave cyl. make sure it is working right. try and adjust in some and see if that helps any. If it dont help, remove the slave cyl and get a flash light and see if you see any metal debris. It could be the throw out bearing.
now thats my "Im broke guess and check" This what you should do.
change the fluid!!, It cant hurt and it soulds like it needs done anyway. Replace the slave cyl with a new one. As slave cyls get old they start holding pressure on the throw out bearing, Or not hold enough. And leak fluid around the seals, regaurdless with the fluid so old its black, I would say its not in real good shape to begain with.
My advice. Check your slave cyl. make sure it is working right. try and adjust in some and see if that helps any. If it dont help, remove the slave cyl and get a flash light and see if you see any metal debris. It could be the throw out bearing.
now thats my "Im broke guess and check" This what you should do.
change the fluid!!, It cant hurt and it soulds like it needs done anyway. Replace the slave cyl with a new one. As slave cyls get old they start holding pressure on the throw out bearing, Or not hold enough. And leak fluid around the seals, regaurdless with the fluid so old its black, I would say its not in real good shape to begain with.
Regarding the slave cyl....There is a leak under the car (about 4 drops a week) and I had assumed it was oil or trans fluid. Upon further inspection it doesn't seem that it is either of the two. Could this be the slave cyl leaking like you said?? it seems to be coming from around the bell housing area but i have not inspected deeply yet.
Clutch has never been replaced.
Melting Slicks
Joined: May 2001
Posts: 3,014
Likes: 18
From: Raleigh, NC
The noise is normal. Flush the fluid and call it good.
The leak is either the slave, or more likely the back of the intake. Is the fluid oil or brake fluid?
The leak is either the slave, or more likely the back of the intake. Is the fluid oil or brake fluid?
Last edited by neat; Aug 26, 2009 at 04:51 PM.
Thread Starter
Drifting
Joined: May 2007
Posts: 1,426
Likes: 165
From: Motor City
The fluid seems to be more like brake fluid than oil based on the smell and how slippery it is. It is really hard to tell but now that i know about the slave i can check that out for som more information.
Where does the slave usually leak...the rubber?
BTW, excuse my newness to C4's in the first post. I just realized that there is a separate reservoir for clutch hydraulic fluid and it does not share the brake fluid. I will have to check this too.
Melting Slicks
Joined: Dec 2004
Posts: 3,284
Likes: 51
From: Jacksonville, FL
St. Jude Donor '08 thru '26
Dual Mass flywheel
GM used a dual Mass flywheel on the zf6spd cars. The noise you hear at idle is the damper part of the D/M assembly. If it is fairly constant, like it's keeping a beat say of once every minute then it's fairly normal. Usually you hear it at very long intervals at idle almost like "what's that noise?" long.
If the motor has an ignition issue causing a miss, then the noise can almost sound like a diesel. Also, the damper springs do wear with time and can get to a point of not controlling the movement of the damper assembly. Usually around 100k I think is what GM said the life is, but I'm not too sure on that.
Mostly, because the zf6 has straight cut gears in 1,2,3,4...it would make a horrible rattling noise from the trans. The D/M flywheel "quiets" that noise by damping out the power pulses of the motor that would cause the gears to "rattle".
If the motor has an ignition issue causing a miss, then the noise can almost sound like a diesel. Also, the damper springs do wear with time and can get to a point of not controlling the movement of the damper assembly. Usually around 100k I think is what GM said the life is, but I'm not too sure on that.
Mostly, because the zf6 has straight cut gears in 1,2,3,4...it would make a horrible rattling noise from the trans. The D/M flywheel "quiets" that noise by damping out the power pulses of the motor that would cause the gears to "rattle".
Melting Slicks
Joined: Dec 2004
Posts: 3,284
Likes: 51
From: Jacksonville, FL
St. Jude Donor '08 thru '26
Sorry, I forgot this.
Yes the reservior for the clutch master cylinder is under the ECM. You have to losen the two nuts, 10mm, and flip the ECM over to get to the clutch M/C cap.
As a rule I change my clutch (and break fluid) fluid about every three yrs. I would say that follow the testing hints at zfdoc.com and see what you come up with. The first sign of the system not working correctly is a baulky gear shifter movement, especially doing from 2nd to 3rd, or trying to get reverse upon cold start up without going thru the pattern before trying to get reverse. There are other test suggestions Bill has also.
I would suck out the fluid from the clutch M/C resivior and add fresh stuff, repeat till you have clear fluid after a few days of driving. The only other way to do a fluid swap without removing the master and the slave is to use a pheonix gun to do a reverse bleed up from the slave to the master.
As a rule I change my clutch (and break fluid) fluid about every three yrs. I would say that follow the testing hints at zfdoc.com and see what you come up with. The first sign of the system not working correctly is a baulky gear shifter movement, especially doing from 2nd to 3rd, or trying to get reverse upon cold start up without going thru the pattern before trying to get reverse. There are other test suggestions Bill has also.
I would suck out the fluid from the clutch M/C resivior and add fresh stuff, repeat till you have clear fluid after a few days of driving. The only other way to do a fluid swap without removing the master and the slave is to use a pheonix gun to do a reverse bleed up from the slave to the master.
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Heel & Toe
Joined: Aug 2009
Posts: 18
Likes: 0
From: Fort Hood TX
My 1990 6 speed makes this exact same sound, disengaging the clutch also makes it stop. While driving next to buildings I've noticed that I can also hear the noise while in gear, so its not just one of those "sitting in the driveway in neutral" noises. No idea on last fluid changes here either. 127,000 miles
Thread Starter
Drifting
Joined: May 2007
Posts: 1,426
Likes: 165
From: Motor City
Thanks alot for the information TomTom. I guess i will plan to change both fluids and do the leak down test that i read about on zfdoc.
As far as changing the fluid in the clutch reservoir i just need to suck out the old fluid and keep topping the reservoir with fresh fluid? So basically after the driving the car the fluids will mix and eventually i will come out with new fluid?
Thanks for all the tips guys i am learning alot of good stuff that i never knew.
My dad bought this car when i was 10 (i am now 22) and i have fallen in love with it over the years. He doenst have time to work on it so i have pretty much taken over. Did the waterpump, plugs and wires last week with no problems
I have a turbo subaru that i have done alot of work to but i love corvettes. Hopefully one day it will be mine!
As far as changing the fluid in the clutch reservoir i just need to suck out the old fluid and keep topping the reservoir with fresh fluid? So basically after the driving the car the fluids will mix and eventually i will come out with new fluid?
Thanks for all the tips guys i am learning alot of good stuff that i never knew.
My dad bought this car when i was 10 (i am now 22) and i have fallen in love with it over the years. He doenst have time to work on it so i have pretty much taken over. Did the waterpump, plugs and wires last week with no problems
I have a turbo subaru that i have done alot of work to but i love corvettes. Hopefully one day it will be mine!
Thread Starter
Drifting
Joined: May 2007
Posts: 1,426
Likes: 165
From: Motor City
Update:
I checked the level in the slave and it was a bit low i believe. It's hard to tell with the moisture cap inside. Are you supposed to check it when the moisture cap is out? It seems if i were to add to the full line and then put the cap inside it would overflow??
Anyways, it doesn't look to be leaking at all as there are no noticeable wet areas near the slave.
So im thinking the leak under the car may be the infamous rear intake gasket leak
I checked the level in the slave and it was a bit low i believe. It's hard to tell with the moisture cap inside. Are you supposed to check it when the moisture cap is out? It seems if i were to add to the full line and then put the cap inside it would overflow??
Anyways, it doesn't look to be leaking at all as there are no noticeable wet areas near the slave.
So im thinking the leak under the car may be the infamous rear intake gasket leak
Melting Slicks
Joined: Dec 2004
Posts: 3,284
Likes: 51
From: Jacksonville, FL
St. Jude Donor '08 thru '26
checking fluid level
No problem on the info....we all need to help each other out!
Ya know it's been so long since I had a clutch M/C with the "top hat", yes remove it and I believe that the proper level should be between the "full" and "add" lines.
Yes again, I use a turkey baster to suck the fluid out of the M/C and just refill with fresh fluid. Over at Bill's site he gives the accepted replacement fluid if you can't get the GM fluid, P/N 12345347 is the GM #. Bill also has an alternative.
You also may want to use this link to look around at the info on our site as a bit of the normal work on a C4 is common to all C4's so our info crosses over very well.
http://www.zr1netregistry.com/
Also, to Silvur, there was a recall on the 90's for a noise similar to what you describe. The recall involved the pilot bearing...alot of 90's had a needle bearing type pilot which made a racket w/ the trans in neutral and the pedal up. GM's answer was to replace the bearing type pilot with the traditional bushing type pilot. I can find the TSB on that as we have it over at our members side at our site.
Tom
Ya know it's been so long since I had a clutch M/C with the "top hat", yes remove it and I believe that the proper level should be between the "full" and "add" lines.
Yes again, I use a turkey baster to suck the fluid out of the M/C and just refill with fresh fluid. Over at Bill's site he gives the accepted replacement fluid if you can't get the GM fluid, P/N 12345347 is the GM #. Bill also has an alternative.
You also may want to use this link to look around at the info on our site as a bit of the normal work on a C4 is common to all C4's so our info crosses over very well.
http://www.zr1netregistry.com/
Also, to Silvur, there was a recall on the 90's for a noise similar to what you describe. The recall involved the pilot bearing...alot of 90's had a needle bearing type pilot which made a racket w/ the trans in neutral and the pedal up. GM's answer was to replace the bearing type pilot with the traditional bushing type pilot. I can find the TSB on that as we have it over at our members side at our site.
Tom
Thread Starter
Drifting
Joined: May 2007
Posts: 1,426
Likes: 165
From: Motor City
No problem on the info....we all need to help each other out!
Ya know it's been so long since I had a clutch M/C with the "top hat", yes remove it and I believe that the proper level should be between the "full" and "add" lines.
Yes again, I use a turkey baster to suck the fluid out of the M/C and just refill with fresh fluid. Over at Bill's site he gives the accepted replacement fluid if you can't get the GM fluid, P/N 12345347 is the GM #. Bill also has an alternative.
You also may want to use this link to look around at the info on our site as a bit of the normal work on a C4 is common to all C4's so our info crosses over very well.
http://www.zr1netregistry.com/
Also, to Silvur, there was a recall on the 90's for a noise similar to what you describe. The recall involved the pilot bearing...alot of 90's had a needle bearing type pilot which made a racket w/ the trans in neutral and the pedal up. GM's answer was to replace the bearing type pilot with the traditional bushing type pilot. I can find the TSB on that as we have it over at our members side at our site.
Tom
Ya know it's been so long since I had a clutch M/C with the "top hat", yes remove it and I believe that the proper level should be between the "full" and "add" lines.
Yes again, I use a turkey baster to suck the fluid out of the M/C and just refill with fresh fluid. Over at Bill's site he gives the accepted replacement fluid if you can't get the GM fluid, P/N 12345347 is the GM #. Bill also has an alternative.
You also may want to use this link to look around at the info on our site as a bit of the normal work on a C4 is common to all C4's so our info crosses over very well.
http://www.zr1netregistry.com/
Also, to Silvur, there was a recall on the 90's for a noise similar to what you describe. The recall involved the pilot bearing...alot of 90's had a needle bearing type pilot which made a racket w/ the trans in neutral and the pedal up. GM's answer was to replace the bearing type pilot with the traditional bushing type pilot. I can find the TSB on that as we have it over at our members side at our site.
Tom
Thanks Tom. I sucked some of the fluid out last night of the mater and refilled it with some new fluid. I will continue to do the same after each time i drive it.
Racer
Joined: Aug 2009
Posts: 274
Likes: 0
From: lexington NC
I keep hearing people talk about the dual mass flawheel and im unsure what that realy means, do you know of a link that does a break down of the zf6? Or can you explain the dual mass set up? I assumed that the ZF6 was very similar to the tremec T-56 used in the 93-97 Fbody and the borg warnner used in the 98-02 ls1 f-body.
thanks
thanks
Drifting
Joined: Oct 2006
Posts: 1,554
Likes: 13
From: Romeoville IL
I keep hearing people talk about the dual mass flawheel and im unsure what that realy means, do you know of a link that does a break down of the zf6? Or can you explain the dual mass set up? I assumed that the ZF6 was very similar to the tremec T-56 used in the 93-97 Fbody and the borg warnner used in the 98-02 ls1 f-body.
thanks
thanks
I would also throw in that while you are doing you maintenance, change out the trans fluid.
