Happened about 1 month ago, and it has been sitting ever since.
I have an 89 4 rnr, standard manual trans 5 speed, bought from a dude, 1 and only owner, who I watched put in a new master cyl for the clutch.
Now then, if the truck is totally off, no key turned in the ignition whatsoever, and you try and put it in any gear you like, it goes in no probs.
However, as soon as you turn the engine over, and try as hard as you might, to get it to go into any gear, it will not go in, no matter how hard you try.
Also, if you turn it off, put in 1st gear, and hold the foot clutch paddle all the way down, and try to start it, it immediately tries to take off, as the engine is turning over. Again i say this, as a bit weird, since i saw the dude put in a new master clutch cyl.
I talked with 1 mech who is not a tranny guy, and he said it sounds like it is time for a tranny rebuild, and that the sychronizers were proly fried on it, which is why it will not go into any gear while engine is on. He also said, it was going to be quite expensive, especially on that older rig.
Anyone else have any ideas, and if the other mech is right, is it going to cost an arm or leg? I just bought this thing, a few months ago, and hate to think of sinking a bunch ofmoney into it allready, after paying 2300 for it.

 

Synchros are not fried, at least not likely.

Just because you saw someone put in a master cylinder doesn't mean:

A. Master cylinder wasn't bad
B. Slave cylinder wasn't bad
C. Clutch pedal bracket wasn't broken
D. Master cylinder rod was adjusted properly

I find it highly unlikely that bad syncros are causing it to shift while not running, but not at all while it is running. You should be at least able to shift in and out while not moving.

 

Ive always found the best way to go about these problems is to just take it apart and put it back together yourself. Because you never know what kind of A-hole had their hands on it.

 

Sounds like the clutch is out of adjustment, and that you're not disengaging the transmission and the engine when you press in the pedal.

 

sounds like ur clutch pedal bracket is broken to me! Just went thru the same on my rig a few months ago.

 

...No no, I can assure you, when the engine is on, you cannot put it into any gear, when it is off, you can shift all you like. So it sounds to me, that the clutch pedal HAS to be working, because when the engine is off, you can push down on pedal, and shift it into gear. Unless when the engine is on, some kind of vacuum is taking place, and the pedal, if it does have a prob, can now no longer disengage the tranny from the engine. Also remember, when the engine is off, I can shift it into 1st gear; then when I turn the key on and the engine tries to turn over, EVEN IF I HAVE THE CLUTCH PEDAL PUSHED IN, it starts to immediately lurch forward, as if I don't have the clutch pedal pushed in at all!
I am totally at a loss here...

 

The clutch is not disengaging.
Like others have said it's likely the master cylinder, slave cylinder or bracket.

 

I dont think you need a clutch to change gears when the engine is off. since there isnt anything rotating.. i may be wrong... but thats what ive always though?

 

We had that same problem few years back, the fork's pivot stud broke, I'll check if the slave cyl. pushes the fork, if it does, pull the rubber boot and get a friend to push the clutch pedal, you may see if the fork pushes the t.o. bearing.good luck.

 

your problem most likely lies in the bellhousing. Does the truck make any weird noises while running?

 

well obviously the clutch isn't disengaging...DUH!.

i can shift all three of my rigs without the clutch (while the motor is not running)..

i'ts probably you're slave cylinder..thats what the problem was on m '80 model..

did you bleed all the air out of the system?????????..

in order to replace the clutch master cylinder, you have to remove the line..thus letting air into the line.so you have to bleed it before it will work at all...then adjust to get it working the best!

 

is the clutch installed properly---i have seen clutches not installed properly ???

 

u dont even need a clutch to get into gear when the motor isnt running. Have u checked the bracket yet? All u gotta do is press the clutch with ur hand and watch the bracket...if it moves AT ALL... its not working properly. Did your clutch used to creek, or squeak when pressed?

 

Um mine squeeks now. Is that a symptom of something about to break?

 

...To black flatty, nope no engine noises. put it in neutral, turn the key over, jumps right up and purrs along.
No squeaking or squealing when pushing in on the pedal.
When the prev Ownr put in a new master cyl, that is all he did; he worked on nothing else nor made any other adjustments. He did bleed the lines, put it in, and rebled them, as he had his wifey mash the pedal, as he worked on it, and added more fluid. So I know he did that right.
but as far as any other adjustments to anything else, none were done.

...To Team 420; I am very non worky on autos, though I have done a few things, I know nothing about 4x4 work, or tranny work at all, standard or auto, though willing to learn. So where do you push the clutch, inside or underneath, with your hand? and what/where is this bracket I need to be looking at?

... To Just Learning, I would have no idea how to know if the clutch were installed correctly.

 

It's definitley nothing wrong with the transmission, there is something wrong somewhere in the clutch hydraulic system. Does the pedal have any resistance? I'm guessing a leak or there is still air bubbles in the system

 

ive had the same thing happen it was my clutch master cylinder... first i would try bleeding the system which has already been stated as a good idea.

 

Guys.
Check slave cylinder, replace if necessary.
Bleed lines...
Adjust clutch pedal...
His clutch is fine, he cant get it into gear when the truck is stopped.
Put transfer case in neutral, press clutch down, and start the truck.
If it still lurches forward then you have issues.
If not, then your transmission is probably going to be fine.

Check slave cylinder for sure, though.

 

Yeah theres a good chance its the slave cylinder too. My buddies truck had a leak and he let it run dry by accident. We got a new slave cylinder, it was only $20, and some fluid. We installed it, topped up the fluid, then bled the system via the bleeder screw on the slave cylinder

 

they're ridiculously easy to change, lol.