i have a 2005 3500 5.9 6 speed with the manual pull in type. whin i pull it in 4high from a dead stop i have nothing. but from 30-35 mph it locks in and 4x4 works like a champ. but when i let off the throttle it disengages and allthough the shift lever is in 4H position i only have 2 wheel drive. no poping grinding or clunking when it disengages. i spoke to a few dealers and they call my truck a "live" front end meaning the front end is in 4x4 all the time, it engages when the lever is pulled in. any help would be great.?.?.?.?

 

I'd check the linkage at the floor board and t-case, i cant remember off the top of my head if its adjustable. Definitely have a weird problem goin on

 

all the linkage is good ive tried adjusting it and nothing has changed so i returned the adjustment to its original position. when i pull it it makes a loud thunk tho as it did before?????

 

On my 06 auto with manual 4x4 shift it works better when moving. Four wheel low they recommend while still moving slow before full stop and I found it works well. When locked it sometimes gets bound so drive straight forward and reverse to relieve and shift while still moving slow. Once you get used to your truck it should work well.

 

Just a guess, but i think you might have an internal problem and need to replace whatever parts have the engagement dogs on them. Not sure about this design but most transmissions have a slight back cut on the two parts that engage the gears to keep them engaged under pressure. When you let off and unload the drivetrain it is falling out of engagement.

Also, try this: when it is properly engaged and pulling feel the lever to see if there is any play in it. if there is slight play then i would say it is not the lever trying to disengage. If it is solid with no play in the direction that you would push it to disengage 4x4 then it is wear or an adjustment issue.

In general bad motor mounts or transmission mount may cause issues too. Not sure it this is common here though. Wish I could help more.

One more question: When it is in 4high and you say it pops out and no grinding clunking. It will not make any noise if front and rear are turning at the same speed because of "live" front design. BUT does it make noise when in 4high, not working and spinning the rear but not the front?

If the linkage is good I think the answer will be inside the case.

 

etn550, ive herd that the nylon ends on the shift fork sometimes come off? im not yet sure on the issue im currently awating good weather and time to get the t-case out and split it