Noise in 4WD (1 Viewer)

[oleblue62]

For the first time in a few months I put the Cruiser in 4WD, remembering I need to do this at least once a month to keep the fluid moving and good. So I engaged 4WD and hit up a muddy field.

When I got back on the road and let off the gas I heard what sounded like driving over a soft rumble strip, no detectable vibration. The noise would go away when accelerating, and come back when coasting and would gradually get softer until completely stopped. This went away when disengaging the t-case, and always came back with it engaged.

Just in case it was some mud and rock causing the noise I drove around a bit more, but no change.

Ideas?

P.S. Couldn't find any other threads specific to this issue in the search.

 

[Wile E Coyote]

Make sure both hubs are engaging when turned to 4wd. If not, then there's your sound.

Wait: When you say road, do you mean dirt road or pavement/concrete? If you drove on dry pavement/concrete with the truck in 4wd, then THAT'S your noise. Don't do that

 

[oleblue62]

Asking out of complete ignorance here, why would driving on wet pavement with 4wd engaged cause a sound when I take my foot off the gas?

 

[Wile E Coyote]

The rumbling while coasting (rumbling without felt vibes as you describe it) could be diff carrier bearings, or a loose pinion causing backlash to change while the gears are on the coast sides of the teeth. It could even be the earliest signs of a bad u-joint, or...
Engaging 4wd at the t-case with the hubs unlocked...that makes an awful noise, don't do that either
It also could just be the sounds of the binding caused by driving a part-time 4wd vehicle in 4wd while on high-traction surfaces.

 

[oleblue62]

Thanks for the input, I'll be hoping for the latter.

 

[BG_TX]

Myself and others have been chasing something similar down... My rear ujoint needed replaced so I replaced all of them in hopes it would remedy the grind/vibe from the front but it didn't.

Another thread here...

I have't torn into yet, it is a priority but I still have 4wd functionality at low speeds so I've been using that as a crutch to put it off. The vibe/grind seems to occur at higher speeds (25mph+) for me.

 

[brett76]

x2 on diff. check your pinion might need tightened down

 

[cruiser88]

jack the front end up and put it on jack stands ,then check