To make story as short as pissble 01 cummins 6 speed pulling a stationary 6000 lbs work table with 165k miles.

A few weeks ago I was exiting the highway from going close to 75 MPH, the ramp is kinda up hill so I shift into neautral and let it drift to the stop sign. I try shifting it into 1-2nd and NOTHING, it wouldn't shift into ANY of the gears. Cars were behind me so first thing my mind told me to do is to shut it off and put it in gear. It worked, there's NO problem shifting the tranny while truck is off, so I kept the clutch pressed in and fired it up while it's in 2nd and moved on.

Tranny is kinda "Hard" shifting it 1st through 4th gears, NO problem shifting 5th and 6th, and it really grinds sometimes DOWN SHIFTING it into 4th 3rd and 2nd UNLESS I do it REAL slow, but still I can feel that 1-4 aren't normal unless truck is off.

Last week AGAIN I couldn't DOWN SHIFT it from 5th coming to a red light, had to shut it off again and start over. Now I need your experience and advice to figure out.

If it's the clutch (Disk isn't slipping at all and it pulls VERY STRONG) then why there's no problems in 5th-6th gears? Or it is the tranny.

Thanks.

Adam

 

It sounds to me like the hydraulics for the clutch are gone. Check out the hydraulics, there are replacement hydro's available. I'm not sure on the 2nd gens, but on the 3rd gens the master lines and slave cylinder are all replaced as a unit.

 

Thanks for the comment, I'll buy a new unti and replace it just to be safe and see if that fixes it, it's my paycheck truck so whatever parts I replace it's never a "Waste" of money.
Would that do it in certain gears only though?

 

its more than likely the the throwout bearing or the hydro unit, another thing... the 5600's are very picky on the type of oil you put in them, there are only 2 types that really work, mopar fluid, and cant remember the other one at this point, but the mopar fluid is the only one i would use, other fluids play hell on the syncros

 

Wow, replaced the clutch slave and master cylinder this evening and so far so good, I think problem is solved but I'll keep you posted tomorrow when I get to drive it more, I do not want to be too excited before I make sure that's what it was, but it shifts without grinding now..Thank you guys so much..

As far as the fluid, could you find an online link for that mopar type, I'll change the fluid in it and move on..

Thanks again guys.

Adam

 

I'm glad to hear the hydro's got you fixed up. I'm not sure on the fluid for the NV trans. I have the G56 and it takes ATF+4. I'm pretty sure that the NV's take something different.