I don't think we have the right diagnosis here. If the slave cylinder was bad the master cylinder would be low. If the clutch disc was worn it would disengage easily. Most likely the problem is either the master cylinder or worn bushings or torn metal in the clutch pedal linkage.

 

Yeah... I'm not sure either...

Boy, talk about passing the buck around on this one...

I was thinking though... it could be something fishy with the shift fork.

 

Worn synchronizers will cause this problem. With the engine off there is no need for the syncronizing of the gears as they are not turning. With the engine running, there is no need for syncronizors when shifting out of gear into neutral. When it is in gear is the shifter loose? Can it be moved left to right a lot? Have you checked the fluid level in the transmission?

 

maybe a recap will help... difficulty moving gear lever into any gear while engine running and vehicle at a standstill. disengages from any gear easily. clutch catches and releases high, not on the floor. with engine off, clutch in, goes into any gear fine. while driving, if I match rpms... as if no clutch, it will seem to be blocked from moving into any gear at first, feels as if it may not go into gear, then will at what seems to be a matching rpm for gear. that's how I've been driving, downshifting while approaching a stop, hoping not to forget to get into 1st prior to stopping. rechecked master cylinder after rereading your notes and there is dark fluid present and it appears filled. no drips or leaks noted. hose descends from below the master cylinder and appears intact. I haven't moved the truck into the garage yet to inspect the Slave cylinder and I was hoping to read more this morning first. so at this point I'm going to wait for further instructions.

when 1st or reverse engaged I have not noticed any slipping going up my steep driveway at home.

I don't have the history of the truck or know the specs on the tranny or rear end but gave my best description previously. it cruises along at highway speed very well and in OD it seems to turn pretty low rpms, (but no tach just my best guess).

just answer.com followed you diagnoses verbatem, check fluid, leak?, slave but added that if the clutch friction plate was worn too thin that the "fingers" may not be able to reach far enough to disengage the rotation of the "shaft".

one last little thing... with engine running when it "gets stuck" and will not go into any gear - attempts to go into reverse result in a bumping noise and feel from what seems behind the driver's seat and definitely below, and sometimes repeated firm attempts to go into a any gear I found that if I can get one to work, ie. 4th, then I can move out of that gear into first... sometimes.

V6 engine starts and runs well with nothing to report other than twice seemed to run a little hotter on the gauge than normal. 3/4 instead of the mid point it typically reads.

JMC... that makes a lot of sense, but I'll try to give you the best description. I don't know how to report the looseness of the gear shift lever, I figured an old work truck deserved a little slack, but yes the gear shifter can move around while in gear, how much? not sure how to qualify, will have to drive around the block and report back later - sorry. Is there another place to check the fluid level in the transmission other than the master cylinder in the engine compartment on the firewall? I'll get the manual out and look in the engine compartment for a dipstick like on an automatic.

Thank you all so much for your help!

 

You say "clutch catches and releases high, not on the floor". Then definitely not a problem with the slave cylinder, or the master cylinder or linkage as I suggested earlier. I would think if it was a problem with the transmission sychronizers, you could shift into any gear while sitting still and the engine running, clutch on the floor of course. Here's my guess now: one of the small springs has come out of the clutch disc and is wedged in there somewhere, not allowing the transmission input shaft to stop spinning. Or it could be something else gone wrong, possibly a locked up pilot bearing, not allowing the input shaft to stop spinning, but of course not providing enough grip to pull the truck.

 

Whatever is wrong, it seems to be consistent with each gear. I've been looking for information regarding the input shaft and it's pilot bearing and I'm not "getting it". What you said makes the most sense. If the engine is off there is no problem shifting - no "input shaft rotation". When the clutch is pushed to the floor, the input rotation is supposed to stop or be disconnected right? Inside the bell housing is the flywheel, pressure plate and the friction plate and I thought that with the clutch in that the engine rotation of the flywheel was not directly connected to the transmission input shaft. So if the input shaft inside the transmission is turning whenever the engine is running does that mean that the friction plate is still somewhat engaged to the flywheel, but like you said, not providing enough friction to move the truck? Other than that, is there one part (the pilot bearing?) that is consistent with each gear and stops or matches the rotation of the input shaft with any gear?
There's a lot going on in a really small area!
Thanks all

 

The more I thought about it, I am more convinced that my theory under number 20 is correct. I actually had a small spring come loose out of the clutch disc once on a 1963 C60 truck. When this happened, I couldn't shift into gear with the engine running. I could however put it into gear and start the engine. I never drove it down the road when this happened because it was parked in the shop when it first showed up and I fixed it before ever driving it out, so I can't tell you how it acted going down the road. In this situation, that small spring wedged itself between the clutch(friction) disc and the flywheel, thus turning the clutch disc that should stop when the clutch is on the floor, and the clutch disc is splined to the transmission input shaft. Now to explain the possibility of a bad pilot bearing: the pilot bearing sets dead center in the flywheel and the front of the transmission input shaft goes into the pilot bearing, if the pilot bearing locks up or just binds it will continue to turn the input shaft instead of acting like a bearing like it's supposed to. If this doesn't answer all your questions, post back.

 

That's symptomatic of a stuck pilot bearing/bushing or problems with the pressure plate and/or disc. I think you are looking at dropping the tranny and seeing what's going on in there. Even at 186k, it's quite likely that's the original clutch in there, and it may just be time for a full clutch overhaul.