Fixing Loose Clutch Pedal

I will say from the beginning that I believe the issue is the clutch master cylinder. However, I would just like some reassurance from y'all before I begin this dreaded fix.

About a week ago, I noticed my clutch pedal was very loose, nearly touching the floor and barely generating any pressure. Fortunately, I was able to shift into 1st and 2nd so that I could drive home. I had to push my car into its parking spot though because I was unable to shift into reverse. My first troubleshooting approach was to bleed the clutch. I had never bled the clutch on this car, but my partner and I did the pump and hold method, and I drastically overfilled the reservoir to ensure the clutch was being fed fluid. I noticed there was definitely air being bled out. With each bleed the reservoir was slowly moving down. I also noticed while bleeding, that despite building a lot of pressure in the clutch, when releasing the bleed screw sometimes the dot 3 fluid would just dribble out rather than a full "squirt" that you would expect.
I am unsure if I bled the clutch correctly but I believe I did, if there is a better procedure for bleeding please let me know.

After this initial bleed, the clutch pedal had more pressure and was able to push its self back into position(in line with the accelerator and brake). However, I wasn't confident and drove the car around for about 10 minutes, and sure enough the clutch lost pressure and was back to the original conditions(stuck on the floor, can't shift). I parked the car and returned in the morning to continue diagnosing. To my surprise the clutch was back with pressure and fully extended. I drove the car to work, (1-2 minutes from my house). The clutch pedal was fine before entering work. After work, I had lost all pressure in the clutch again.

I have looked around the clutch pedal on the inside of the car and don't notice any fluid leaking through the firewall. I am not terribly knowledgable about slave/master clutch cylinders so any help would be appreciated.

I may just be bleeding the clutch incorrectly, but the erratic behavior of the clutch working and not working without any intervention on my part is a little baffling. I should also note that the loss in clutch pedal pressure was not some spontaneous "blow out,", but happened over night while the car was unused.

I also have this part lying around from several year back, and I believe it is a clutch master cylinder for the ms6 but can't recall. If this is the correct part, please let me know.

 

@phate thoughts?

It does sound like the slave cylinder has gone bad but these cars can be a bitch to get everything bled correctly. Are you able to use a power bleeder?

 

My speed 6 first time I rebuilt it, and used a higher clamping pressure plate and clutch. I inspected the pedal mount for cracks (happens on these)
I had removed slave and upon reinstall followed typical one person process: vacuum setup on slave cylinder bleeder used over a quart of brake fluid and still could not remove a air bubble somewhere in system. Had some of same pedal feel questions.
So bought lots more brake fluid and a pressure style of bleeder that attaches to top of brake reservoir that then pushes fluid. This worked but still it takes patience, lots of fluid, luck and finally got it working correctly. Sorry I have no short cuts to get it done easier. Hopefully others will have more help.

 

When the slave goes bad, it will leak fluid. I think the slave is OK in this case.


The master, though, I think you're headed in the right direction @syzygy. I've had several go "bad" where the internal O-ring on the piston gets chewed up over time and fluid gets past. It's all internal to the master, so you never see the leak, but the behavior is as-described. I carry master rebuild kits with me in the race trailer because it's happened to me so many times.

 

Okay thank you. I think I will start with the master as I can see no visible leaking from the slave, and it does seem to be an internal issue. If you don't mind, does the master cylinder look like the image I attached in the original post?

 

Yep

 

Thank you. I will work on the install some time this week and report back my findings.

 

Any tips for removing the bottom hose? Struggling to get a wrench around the fitting.


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Nevermind I’m just a moron, and was trying to loosen the wrong thing.


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