I need help!! My truck is a 1991 d350, 5.9L diesel, 360 getrag manual trans., etc. I also have a 1990 d350 I am robbing parts off of. The other day, I was driving and my truck got stuck in 2nd gear. I thought it might be the slave cylinder, so I put the slave cylinder on from the parts truck and it worked for about a few hours then it got stuck again when I was driving. I figured if anyone can help me it's you guys. any suggestions or ideas are welcome. thanks in advance - Clint

 

First of all, Welcome!!! Now to your problem. Have you had any problems getting the tranny to shift other than second? Have you tried to see if the truck would roll with the clutch pushed in while in gear? If the answer to the second question is a yes, then you need to start looking other places. I am wondering about a worn/bent/otherwise damaged shifting fork or a gear problem. Have you checked the tranny for the proper amount of oil lately? I am sure that others will chime in with lots of suggestions. Good luck and let us know what you find.
Tom

 

Thanks!! No , this is the first problem with the tranny. I've had the truck for just a couple of months. When I bought the truck, the previous owner put a 2 inch trailer ball on top of the shifter....the shifter was wobbly and it looked in a bind with the weight from the trailer ball...so I tighten the shifter and replaced the trailer ball with a normal shifter ****. that was about 2-3 weeks ago...I don't know if that could have contributed to the problem I have now. - Clint

 

I had the same problem in my 89 it was bad shifting forks, they are aluminum and wear out. I think the aftermarket ones are steel.

 

I don't know the d350 so am going to talk manual transmissions in general.
First, if it is stuck in any gear, what made you change the slave cylinder? That is a clutch part. So if by changing the slave cylinder did improve the changes then perhaps you have a dragging clutch. As MnTom said.
With the engine and brakes off, have someone rock the truck back and forth to the extent of the drive train slop. While it is being rocked, try and move the gearshift into neutral. If it suddenly moves into neutral then that is a good indication of a clutch problem. If it stays in gear then the chances are that it is internal in the tranni, which for this discussion lets call problem #2
If it slipped into neutral when rocking, now start it up. Push the clutch in and see if it goes into first or reverse easily. Preferably do this on some level ground with the brakes off. If it goes into gear but the truck jumps a little or even starts to move with the clutch depressed, then it is a clutch problem. Try placing it into another gear such as 4th. Does it go in easily or is it stiff? Leave it in 4th and shut the motor off. Now push the clutch in and see if you can easily place it in neutral If it moves hard this may (but not necessarily) indicate a clutch problem.
Clutch problems can be a variety of things but I am not going to go into all the possibilities yet. First thing to check is to put the brakes on and/or chock the wheels. Then slide underneath and while someone depresses the clutch fully, check how much travel there is on the part that the slave cylinder pushes against. Also have them pump the clutch pedal a few times and see if this changes the degree of movement. Take a note or mark the maximum travel and then have them hold the clutch pedal fully down for about two minutes. See if there is any slow movement back to the relaxed position. If there is, then there is probably a leak in the master cylinder. BTW, is the fluid in the master cylinder full? Did you bleed the system after you changed the slave cylinder?
If it is problem #2, that unfortunately is a whole new ball game. Do the checks as noted above and then we will go from there.