NH T4.75 tier 3, won't go into 4WD

   / NH T4.75 tier 3, won't go into 4WD #1  

Sandpiper270

New member
Joined
Feb 9, 2016
Messages
5
Location
Hermiston, OR
Tractor
JD 2020, JD 3230, NH T4.75
This is a 2013 model, same one that has the fan motor issue. It also won't go into 4WD. Waiting for the dealer to get back to me with a call or visit from a mechanic. Getting tired of waiting and it seems this should not be hard to fix. From what I understand, the 4WD is engaged by a spring that surrounds the shaft the sends power to the front. It is released by hydraulic pressure when you turn it off. So when the tractor is not running, no pressure, and it should try to go to 4WD. I have verified that there is 1.6 amps going into the solenoid when in the off position, and no current in the on position. So that seems good. I can't feel the solenoid click when operated, but that might be normal. I have verified that with one front wheel turning, and the other not turning, the drive shaft to the front does turn. So it seems the problem must be in the 4WD housing where the solenoid controls the operation. I suspect the 21 tooth sleeve is not moving when the spring tries to slide it along the shaft to engage 4WD. I would like to drop that off housing and look inside, but don't know what can of worms I would be getting into, and I think I would have to drain almost 10 gallons of oil to do it.

I have tried driving in circles to try and make the parts spin relative to each other, tried it going backwards, to no avail. I don't hear any bad sounds from the thing, so suspect the sleeve just doesn't want to slide. Any more things I should try? I am tempted to whack it with a big hammer to shake it loose, but I won't. :eek:
 
   / NH T4.75 tier 3, won't go into 4WD
  • Thread Starter
#2  
I have verified that there is 1.6 amps going into the solenoid when in the off position, and no current in the on position. So that seems good. I can't feel the solenoid click when operated, but that might be normal. I have verified that with one front wheel turning, and the other not turning, the drive shaft to the front does turn.

Mechanic just came by and looked at it. Found that the front driveshaft coupler was stripped, and I was wrong about it being OK. Unfortunately the teeth on the front shaft coming from the axle are also badly worn and need replaced. At least I know now where we are headed.

Dave
 
   / NH T4.75 tier 3, won't go into 4WD
  • Thread Starter
#3  
Mechanic just came by and looked at it. Found that the front driveshaft coupler was stripped, and I was wrong about it being OK. Unfortunately the teeth on the front shaft coming from the axle are also badly worn and need replaced. At least I know now where we are headed.

Dave

I thought I would update this. I bought the tractor used from a local dealer. Even though there was no warranty, the dealer picked up the tab for fixing this. They replaced the drive shaft and front differential parts. Thanks to the local dealer here in Hermiston, OR.
 

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