Never experienced a problem in using 4WD. Used sparingly. Shifted flawless in and out of 4WD Low until 60,000 mile service at dealership changing all fluids in transmission, transfer case, front and rear end with mopar products. 200 miles later, first time trying to use 4WD low, grinds horrible, have to force it into gear. Seems to drive OK when in 4WD, but shifting back, more grinding. Dealer said old fluids coated the gears and new are fresh. HO, HO, HO. Dealer offered to replace transfer case under extended warranty. I am not convinced. Any suggestions and/or advice as to what really happened?

 

Probably forgot to add fluid back or left the drain loose and you lost the fluid on the way home.

 

I would guess there is something causing the trans to rotate through...did they adjust the trans?? The case itself is subject to the input from the trans...if the trans is rotating through, the case will grind every time. Transmissions will still spin the output shaft in neutral from parasitic drag of the fluid...get enough drag and you will get "neutral creep" where the vehicle will inch forward even though the trans is in neutral.

I have no idea why they think oil coats anything and "sticks"...different fluids in the transfercase will make shifting from 2wd to 4wd easier, but there isn't anything to keep the thing from grinding when shift from HI to LO or LO to HI.

The absolute first thing I would do is verify what fluids they replaced, that those fluids appear to be what is in your transfercase and transmission, and that the fluid levels are correct.

 

Today I am replacing 1 quart transfer case fluid with purple max ATF and 1 quart each axle with valvoline full syn 75w-140. Drove about 100 miles yesterday and LS seems to be trying to catch in starts and slow turns. Also plan a close inspection of visable parts. Will post results later.