I have a '84 4x4 four speed manual with a granny-1st. It sat for years before i got it and i am trying to get her back up to speed. I am new to being a mechanic but am learning as i go.

I am having clutch issues and cant get her into gear. I can run through all the gears when the engine is off, but when running, I cannot get into any gears except reverse. This unit has a hydraulic clutch. The clutch does not feel spongey - has decent resistance all the way through and bounces back when i let go of it. The clutch master cylinder looks new, the slave looks old but both look to be working fine - there are no leaks and i set up my camera on the frame and filmed the slave pushing the clutch fork and forth and there seems to be a good range of motion.

I opened up the fill-plug on the transmission and there was too much fluid in it - it started to overflow immediately (got about 10oz from the fill-plug) and the fluid was thick, black, a little more syrupy than it seems like it should be, and smelled really wrong - like the fluid that forms when vegetables rot in a bowl with a hint of sewage / methane. rather rancid smelling. It looks as though it has taken on water and perhaps emulsified a bit and is dirty as well - perhaps spoiling (does that happen?).

A buddy thinks that the fluid is all of the problem, and i am about to run to NAPA and get some more to fill her back up with fresh. I have her draining right now and will let her drip till i get back from the auto parts store. I am skeptical that this is the whole problem though... anyone have any thoughts?

She was shifting fairly well up until a few days ago, but would have trouble getting into gear every now and then, and the shift itself felt "heavy" - as though i could feel it engaging hard (through the stick) as it connected into gear while the clutch was depressed. I don't think it's the clutch but i'm not sure...

 

if your gonna try new fluid, try ATF first not gear oil. it's pretty corrosive to anything except the steel/plastic components in the transmission and should eat up anything left inside there. some people run ATF in those transmissions without issue, if your gonna do some heavy hauling or long use, use gear oil though.

if that doesn't work as a quick fix, definitely take it to a good tranny shop

 

Sounds like the wrong fluid, which would be an issue. If the fresh ATF that Mathew mentioned helps, drive it some, drain it, put some more fresh stuff in. Do that a few times to try and get all that gunk out.
Don't know if that's the cause of your problem or why it's in there, but it can't be helping the situation.

 

sounds like a fork is bent. if you start the truck in gear and run down the road and it won't a shift to the next gear you've bent a shift fork.. the guild smelling bad is a mystery.. probably should take top. plate off and inspect everything