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Manual transmission clutch no pressure.

2K views 7 replies 5 participants last post by  SoK66 
#1 ·
I drove to work this morning no problem (felt same as usual) & when I was about to start the engine around 7pm I realized my clutch pedal was sinking all the way down. Barely drove to my friends place (5mins away from work) without clutch (thank goodness I didn’t grind). Now we are both trying to figure out what the hell went wrong. I checked the place where I was parked. Clean. Engine bay clean. No sign of leak. Brake fluid level good. I tried to bleed the clutch slave cylinder but failed to do so. Is it my master cylinder that went bad? Or something in the transmission that gave out???

Can someone with similar experience please educate me?
 
#5 ·
I once had a '95 Geo Prizm (poor man's Corolla :laughing:). Bought it for a song off a guy on ebay. Drove it for a few days when suddenly on the way home from work, I had the clutch in for a few seconds at a red light and the engine started bogging down and stalled. Pretty sure the last owner knew about it because the shift boot was loose (thinking it was a problem with the shift lever or something) and he apparently tried to glue it back into place. Long story short, the car had only about 70k miles, but both the master and slave cylinders were trashed internally. Looked like the fluid had never been changed & bled, and the aluminum pistons and cylinder walls were heavily pitted, so they finally stopped holding pressure. No leaks.

On a more directly related note, my brake master cylinder (2008 JK, only 110k miles) was slowly oozing fluid past the plunger and into the booster. I had no symptoms of trouble, but only found it during my engine swap. If you haven't been into your brakes or clutch system that far, it might be good to at least mentally prepare for replacing the booster, brake and clutch masters, and possibly the clutch slave as well. This is all assuming you're talking about your JK with ~300k miles...
 
#6 ·
It's entirely possible for a master cylinder to leak back intro the reservoir without leaking externally, I think.
 
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#7 ·
Just bled the clutch which was SOB. Didn’t find any sign of leak through my investigation. Also I found out my slave cylinder is aftermarket don’t know what brand. Now it drives like how it should. I think last time when I did brakes (changed to ceramic pads) about 5k miles I didn’t top off the brake fluid & as the pads wore out some air got in the clutch master cylinder (I do park on uneven pavement). Next time when I do brake upgrade (driving to work is borderline off-roading) I’ll probably just swap out the whole damn thing (master/slave cylinder).
 
#8 ·
We just had this happen a few months ago with our tour JK, a 2008. Slave cylinder suddenly failed, thankfully right in front of our business rather thanout in the sticks with a tour group on board. Replaced the master & slave cylinders and all is working just fine now.
 
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