I just changed my front differential to 75w90NS from Red Line. I've never paid attention before, but going highway speeds in 4 wheel high and letting off the gas it sounds like a truck using it's transmission to slow it down (it's an automatic and I don't think it's actually the tranny). I don't recall if the sound was there previously. I also don't know if it's a sound that became louder because I put a full synthetic up there. It doesn't seem to happen at slower speeds. Also I cheated and just pumped the fluid out without cracking open the diff because it didn't look like I could torque the bolts properly.

It seems to only happens in 4x4 at higher speeds (55mph maybe as low as 40). It doesn't happen when it's in 2WD. I also replaced the rear differential fluid with Red Line 75W140 yesterday (not sure if that matters or not). The truck is almost at 76K. Dodge performed the 60K maint including changing the transfer case fluid. The coolant was done around 63K.

This normal or is there a problem with it? My mother in law wants to drive it to Texas in May and I want to make sure it won't be a problem for her.

Thanks in advance.

 

You're not doing this on paved roads by any chance, are you?

 

Yeah I wanted to make sure it was working properly... I'm guessing that's a bad thing? :-(

 

Our Dakotas have part time 4wd. Read below, or Google 'part time 4wd on pavement', and you will realize how bad it is. Use it on loose traction only.

http://www.4x4abc.com/4WD101/def_turnpart.html

 

Unfortunatly not all. Im a Full-Timer

 

Good thing i only drove it a mile or so. I knew it was part time but unfortunately not a whole lot of loose pavement to test :-) Thanks for letting me know!

 

Dakotaff that's a great site... I think the best reason not to drive in 4x4 on dry pavement is the pic they have of one guy's transfer case cracked in half:

http://www.rubicon-trail.com/4WD101/driveline-bind.html

Funny you'd think the owner's manual would state specifically... NEVER EVER USE 4WD on dry pavement. Doing so could cause severe damage to the truck.

This is my first 4x4 so I didn't know that would happen.

 

What the owners manual does say is:

The NV233/243 transfer case is designed to be driven in
the 2 wheel drive position (2WD) for normal street and
highway conditions (dry hard surfaced roads).

When additional traction is required, the transfer case
4HI and 4LO positions can be used to lock the front and
rear driveshafts together and force the front and rear
wheels to rotate at the same speed. This is accomplished
by rotating the 4WD Control Switch to the desired
position - see Shifting Procedure section for specific
shifting instructions. The 4HI and 4LO positions are
designed for loose or slippery road surfaces only. Driving
in the 4HI and 4LO positions on dry hard-surfaced roads
may cause increased tire wear and damage to the driveline
components.

The problem is we never actually read the owners manual, or simply forget what the damn thing says after a while.