Ever hyperextend your knee when you step on your clutch pedal and it goes to the floor with no resistance? That is because the hydraulic system has failed, if it is hydraulic. If it isn't hydraulic, then it means the cable let loose. If it isn't the hydraulic system or the cable, then it is your knee that needs work. I'll cover the just the hydraulic system for now in this instructable.
Step 1: Master Cylinder removal
If you look in the engine bay, there will most likely be two hydraulic units - one for the brakes, and one for the clutch. You can tell which one the clutch pedal is connected to just by looking and listening - have a partner slam the clutch pedal down a few times. The one that sounds clunky or that you can feel the pedal clink on - that's it.
There is one other way to tell - it will be leaking all over!
First, loosen the line fittings - it's nearly impossible to do this later, so do it now while it is still bolted fast and you can get some leverage on it.
There is also going to be two or three bolts holding it in - use a wrench or socket to remove the bolts. Put the bolts in a bowl or container, not in your pocket! And don't leave them on the top of the fender - they will disappear in the grass or go down the gutter - every time!
Step 2: Clutch Pedal release
Pull your pants up and cinch up your belt - you are about to bend over! Open the drivers door and go headfirst into the footwell. Peer up at the top of the clutch pedal lever and you will see a pin or bolt holding the clutch lever to the actuating rod on the end of the master cylinder - disconnect this.
Take care while you are doing this, your big bottom is facing the neighbors and it may not be covered - that's why I told you to pull up your pants, Cletus!
Step 3: Be the Master of that Cylinder
Now, lets take that leaky thing apart. Look right down the barrel of it, wipe away the grease, and pick out the small retaining ring. Carefully withdraw the actuating rod and anything that comes with it.
Step 4: Here's the retaining ring
Yeah, its the retaining ring alright.
See how greasy it is? Should you stop now and clean everything with a moist towelet? No way ! get your hands dirty like a real mechanic. And when your hands are seriously greasy, wipe them on your pants!
Yeah, that's right, because your a real mechanic and not afraid of grease. High marks to those of you who can also pause to eat a bag of potato chips at this time - now that's a mechanic!
Step 5: Here it is with its guts all laid out
At this point, it simply pulls apart. Sometimes the piston assembly will stick and you have to give it a sharp blow so it all comes apart. If it is super stubborn, shoot some compressed air into the the line fitting - spectacular display of flinging parts and swearing to follow.
What we are going to do now is clean out the bore of the Master cylinder and check for pitting or sharp burs of any type. If it is pitted, start drinkin early because your day is over and you are waiting on parts - you need a new master cylinder.
If it is not pitted and any burs you feel can be cleaned up with a light touch of emery cloth, then you are still in business! Note which way the little rubber cups face, and then peel em off. Clean out entire assembly with clean brake fluid and a rag and replace rubber bits from the kit you bought, or will buy.
Step 6: Clean everything to the best of your ability
Clean is relative - it aint surgery, but it aint a sewar line either. Make it clean enough to eat off of . . . then eat off of it. That's a good mechanic!
Step 7: It goes back together quick
Seriously, once you remember how it goes back together, you are only twenty minutes away from motoring away. Put the piston assembly back together. fill it up with brake fluid and push the rod in a few times until it squirts out violently - oops, go outside first!
Slide that thing back in the hole - and bolt it up.
Connect the clutch pedal
Attach the fluid line, fill with fluid.
Jump inside and press the pedal a few times. The resistance will build rather quickly.
If it doesn't, you will have to bleed it.
Don't worry, its not a terrible job to bleed it as long as you don't ask your wife/husband or girlfriend/boyfriend for help.
If you make this mistake, see my instructable on " How to file for divorce or break up in ten minutes or less because you tried bleeding a hydraulic system with someone with whom you cannot Communicate"