Sticking Clutch Pedal

[RonnieH]

Awhile back, I had an issue with the clutch pedal sticking. I replaced the fluid, cleaned the master cylinder and flushed new fluid thru the system 4/5 times and the problem seemed to disappear. However, it has happened again and seems to be triggered by cold weather (25 degrees or lower). I can start the car in the garage and shift into 1st. After accelerating and trying to go to 2nd, the clutch won't engage - only a little clutch pedal. I can idle thru the subdivision pumping the clutch as I go and lifting the clutch pedal manually. I can turn off the key and w/o the motor running, shift into 2nd. When I hit the key, be ready to go as the clutch is only partially disengaged. Once I repeat this a couple of times, the clutch will function normally and and all is well until the car is returned to the garage and sits there a couple of days. One odd thing is I can pump the clutch several times prior to starting the car the first time and all is well. The clutch only malfunctions once the clutch is engaged the first time after starting the car. There is no fluid leakage and I have bled the master cylinder several times using various techniques.

I'm thinking of replacing the master cylinder. Just guessing, since the problem only occurs when it is very cold, maybe some of the seals in the master cylinder have gotten old and brittle causing a lot of friction and therefore not operating normally. At this point, if the slave cylinder were to be bad, I would have to let the dealer replace it as I don't have a lift in the garage.

Any thoughts/ideas would be greatly appreciated. If I replace the master cylinder, I would think it should be a fairly straightforward process, but I am hoping someone may have a good link for replacement of the master cylinder. Someone who has done it before is always a good resource to eliminate potential problems and make the process go smoother. Looking on the web, I was not able to find any good articles.

Thanks in advance for any help/ideas. If anyone has a good article they could send via e-mail, let me know and I will provide my e-mail address.

 

[Toms007]

I was hoping that the flushing of the system was going to fix the problem, Ronnie. Hopefully one of the experts will jump in here to help you out.:ugh

 

[RonnieH]

More Issues

Took the car out today to get in a ride before tomorrow's snow. My normal procedure for engaging/disengaging the clutch didn't work. Left the car in the driveway and went back in the garage and to my surprise I saw hydraulic fluid on the floor - had eaten thru the epoxy floor. Checked the master cylinder and it was low. Added fluid and clutch came back to life.

Now makes me think a hydraulic line from the master cylinder is leaking or worse - the slave cylinder may be bad and leaking. I will and troubleshoot the master cylinder and if it is not leaking, will probably have to take it to the dealer to check out the slave cylinder.

 

[dadaroo]

Double check the connection to the master cylinder. Hope it is not the slave.

When you said you flushed the system, did you actually do that? Bleeding is the ONLY way to flush the system. The "Ranger" method is not a flush.

 

[RonnieH]

Flushing

When I "flushed" the system,removed the old fluid, cleaned the reservoir, put in new fluid and pumped the clutch about 20-30 times, removed the contaminated fluid and pumped again to displace the old fluid from the slave cylinder. Repeated this process 4 times until no more "old" fluid came back to the reservoir. I "bled" the master cylinder a couple of times using various quick/easy methods. Not having access to a lift, I did not bleed the slave as it requires dropping the exhaust and removing the drive line tunnel cover.

I am hoping the leak is with the master cylinder - space and access is tight to replace it, but taking my time, it can be done. Replacing the slave will be a job I'll have to farm out to the dealer.

I'm still trying to locate any procedures for replacing the master cylinder. Hoping someone will respond with a link. Even Froggy on You Tube does not have a video for this. Prices online range from $60-$230 (Mid-America). Beginning in 2003, GM started installing a heavy-duty system,same as ZO6. Most jobbers online supply this "heavy duty" master cylinder. If it solves the problem, fantastic. If not, I'm only out about $60-$70 and some time/frustration, but it would beat leaving at the dealer for several days. I'm in a rural area, so travelling back/forth to the dealer is an issue since someone would have to travel and pick me up and take me back. It's about 70 miles each way.

 

[dadaroo]

Reaching the clutch slave bleeder from the engine compartment:

I found this from the Forum, not my writeup. From others it will work.

“One way that I have found is to pull the intake manifold for the C5 and C6 Corvettes. We have ported hundreds of manifolds so we have become proficient at pulling intake manifolds. (Total time to clean head ports and put it back on about 45min.) This will allow one to lay in and across the engine bay. With your head right at the firewall with a 9mm combination wrench and a light just barely have enough room to see the port, pop off the rubber cap (leave it off) and open it while someone else is depressing the clutch pedal. Bleed it just like a brake system, one person (A) holds pedal, the other (B) opens the port till fluid pours out and then closes, (A) pumps pedal till firm again and then repeat till fluid is clear, 3-12 cycles. Remember to check the reservoir! Refill it so you do not get any air in the line."


Some info on MC removal.

Changing trans master cylinder! - Corvette Forum : DigitalCorvettes.com Corvette Forums


About 3/4 way in this one they discuss disconnecting the slave line from the MC.

C5 & C6 Corvette Clutch Installation | CC Tech - Corvette Blog, Restoration and Repair

 

[RonnieH]

Thanks for the link

The link for the MC removal/replacement is exactly what I need. The write up makes it seem like a lot of work. Will check the MC out tomorrow and use the write up to do a "dry run". Probably will remove the windshield washer reservoir to see if I can feel any leakage around the master cylinder or MC hydraulic line before diving in and doing a replacement.

Thanks so much for your help.

 

[dadaroo]

Let me know if you run into any problems.

 

[Gdad45]

M/C replacement

Let me know if you run into any problems.

I just replaced the master cylinder on mine this week. Relatively simple. With the Inspection cover part of the fender liner off all is revealed.

I unclipped the reservoir from the bracket and pulled it down and out with the master cylinder (empty it first). That allows the master cylinder to be rotated in order to work out the roll pin. Now you get to bleed it. Various methods mentioned. I have the bottom out of mine so I can get to the bleed valve.

 

[RonnieH]

MC Replacement Question

Gdad45,

When you replaced the master cylinder, did you have trouble removing/replacing hydraulic line? I thought I remembered reading somewhere it took a special tool to remove the hydraulic line. I'm still trying to determine for sure whether mine is the master or slave cylinder - as of now, I haven't pinpointed the exact cause of my problem.

When you say you had the bottom out of yours and you bled it, were you referring to the exhaust and driveline pan and bleeding the slave cylinder?

Thanks for your response.

 

[Gdad45]

There is a metal tube coming from the slave cylinder.

There is a flex line coming from the master cylinder.

The special tool is used to separate the hard tube from the flex line.
Leave that alone. Push out the roll pin at the end of the master cylinder to take of the flex line.

Yes, the exhaust and pan are off.