Lost clutch pedal, but clutch fluid still all there??

[TheBrightSide]

As the title states, I started randomly loosing my clutch pedal today. Started gradually feeling dead pedal all the way at the top, with it flopping down, all the way until it only had like about 1 or 2 inches left to disengage at the absolute bottom; and it would engage like bare millimeters off the ground it felt like.

I checked to see if anything was leaking, as I have a GTO separate clutch fluid/master cylinder reservoir in the engine bay; and nothing was leaking. In fact, the clutch line was clean and the fluid was as full as it ever was. I started pumping the pedal with the reservoir cap off and it gained enough pressure to get me like 10 minutes home, with me limping the car as it began losing pressure again..

I didn't physically see anything leak and drip onto the ground underneath the car. I haven't checked, but I was figuring air somehow got in; maybe my master cylinder somehow failed, but my fluid is still there though(?); or something inside my transmission, like the concentric slave cylinder and release bearing support have melted or broke apart? Can someone tell me in what circumstances clutch fluid would still be completely there, if I'm losing the clutch pedal hydraulics??

I also removed the factory clutch pedal return/assist spring and rigged up my own DIY return spring, as I didn't like how the factory one would hold the pedal to the ground as you got it to the bottom of the travel. Thankfully I had my DIY spring and got rid of that factory one, or I would've been manually pulling the clutch pedal up to go anywhere at all, or needing a tow today most likely.

[FASTFATBOY]

Bad master or slave

[Risingson05]

Melted bearing support cup

[CamaroCracka]

If you don't see fluid leaking out of the bellhousing, start with the master since it is a lot easier to replace than a trans. Or even better, get a scope and see if you can see anything with the CSC.

[TheBrightSide]

Hmm... so I figured that since I can regain pressure back with the clutch fluid reservoir open, I pumped the pedal like 30-50 times, and then cracked the slave cylinder bleeder to bleed the clutch pedal. It didn't use a lot of clutch fluid, so I barely topped it off; I'm merely bleeding just to let any excess air out.

I do hear something traveling through the line(s) as I start cracking the bleed valve loose with my small 8mm hex combo wrench. I put back on the cap to the clutch fluid reservoir and then pump the pedal about 30-40 times, and then crack the bleeder to bleed the slave cylinder once again. At this point, I re-open the fluid reservoir, top it off, pump the pedal 20-30 times; put the lid on, and then pump the pedal roughly 50-60 times.

Everything seems to be okay now, although I haven't taken it on an actual drive yet. I will update as I drive the car, as I never bled the clutch pedal since the day I got the car roughly a year ago... At times, I thought the pedal was getting a tad softer, but thought it was fine, since there was no loss of pedal pressure at all (from the very start of pedal travel).

Also, I had gotten a long close-ended 8/10 mm hex combo wrench, to use for the clutch slave cylinder; but the way the bleed valve is positioned, only a normal/small sized 8mm hex wrench (closed end recommended) would fit, facing TOP-down (it may differ per person). I only had barely enough travel to turn the wrench, but it was more than enough to bleed; although if I needed to turn the wrench any more, the 90-degree angle the wrench began to turn to, would start riding against the transmission bell-housing and stop. Such a PITA.... I made sure not to over-tighten the bleed valve, as this might make it harder in the future, and also mess up the spot that the wrench can be placed.

[TheBrightSide]

By the way, I ended up replacing with an AC Delco clutch master cylinder (P/N: 174-1179), which fixed my issue (that I had assumed). The GM equivalent of that CMC, is P/N: 92067134. GM P/N 92199594 is pretty much the same thing as the other CMC, just with a different branded part or two, but essentially the same labeling, etc.

I think these are all the same part, just different OEM (or equivalent) brands; which means that they're all actually FTE branded...? I'm so confused with the re-branding? Aside from that, there's a few actual aftermarket brands out there, such as Sachs or Luk.

[CamaroCracka]

GM used to use a lot of Luk and Sachs parts, and not just in Camaros.