OK, so I have a 1993 B2200 5spd. Out of no where my pedal got really soft and it didn't want to go into gear unless the truck was turned off. (on the 400 going north to barrie) Once I got to where I was going, after numerous stalls and jamming it into gear. ( I ripped the shift **** right off the shifter) I had a friend look at it. When he got into the truck, started it and tried everything, it worked fine. The pedal was still a little soft but no problem running the gears. We bled the clucth and all kinds of interesting things came out. It seems to be fine for now but the pedal still seems to be soft. Any ideas???? Everyone I talk to seems lost on this misterious happening.

 

It is either the slave cylinder ( will have an external leak if you pull the boot back) Master cylinder ( look under the dash at the inner firewall for signs of fluid leaking from the back of the master) ( can also leak internally since it has 2 cups) or the rubber hose going to the slave cylinder.

 

I've checked for leaks and that doesn't seem to be the problem. Everything is dry. MAybe it is leaking internally. I didn't know that was possible.

 

Yes internal leaking IS possible (it's also called bypassing). The piston cups are shaped so they taper outward slightly, and the tips have an internal chamfer. This is so that the moment the slightest pressure is applied, the cups flare outward giving a firm seal capable of resisting the peak pressure which follows. Being thinner, the tips of the cups are the first to wear. This shows up as residue in the clutch fluid which typically is darkened and can contain tiny particles of detached skirt. These particles can migrate anywhere in the system and if they lodge between the piston cup and cylinder wall, cause the piston(s) to bypass fluid. Similarly, if you have rusting of the hydraulic lines, fine rust particles can have the identical result.
Your comment about "all kinds of interesting things came out" suggests you've reached clutch hydraulics overhaul time. A good test is (a) measure your clutch free travel and compare to manufacturer's spec. (b) Depress the clutch very, very slowly and note how far it has to go before it "bites", and if the "bite" is solid.
If one cylinder has gone, please replace/ rebuild BOTH, and clean/ replace the lines and do the reservoir thoroughly too. Make sure your working conditions are scrupulously clean and use only clean new lint-free wipes. Bleed the system really well too, and use only brand new brake fluid fresh from an unopened container. Brake fluid absorbs water beautifully, and an old partially used can of the stuff will be contaminated with water, and if in a tin rather than a plastic container, will contain rust as well.
When you've finished, find a plastic container just big enough to hold your fluid, having a good seal, and keep your extra brake fluid in it (discard your bled fluid). That way you can keep fluid indefinitely without risk of water or rust contamination.

 

thanks everyone for the responses. I'm pretty sure it was my slave cylinder because it crapped out on me on the way home today and had to get it towed. It's not easy driving a clutchless truck downtown toronto. lol. Anyways, it's at the shop and a new clutch master and slave will be put into it first thing tomorrow. HOpEFULLY it works and I don't have to do anything else. Thanks!!!!