1996 4Runner, 4WD works when going in a straight line, however, when steering wheel turned, clunking noise seems like it is coming from the front diff. area. Sounds pretty bad, and don't want to drive it (in 4WD) as is.

Truck on a lift, so checked the vacuum signal to both sides of the "interlock" mechanism. Vacuum is good and stable at both sides of the "diaphragm" when turning steering wheel (all the time really).

Any and all help appreciated.

 

Well it is on a lift turn the wheels look at your CV axles good bet one is making the noise .

 

Thanks for the reply. All CV boots look good, and are not making noise. This _really_ seems like (sounds like) the mechanism that engages the 4WD, the noise is central to the vehicle (as opposed to being out at the wheel(s)).

 

Huh? Should have good vacuum to ONE side of the actuator and NOT to the other. Vacuum on both at once suggests a bad VSV on one side.

 

maybe the transfer case is in H4Lc which means that the center diff is locked resulting in driveline bind. When on pavement, set the transfer lever to H4/H2. H4 is AWD, meaning 4WD with the center diff open (unlocked) condition

 

I should have been more clear. Have good vacuum to one side of the actuator when not in 4WD, and then good vacuum to the other side when in 4WD.

I am not exactly sure how this 4WD system works, I am used to the manual locking hubs on my '87.

The noise _does_ sound like and feel like a CV joint failure, but does not manifest itself in 2WD. But if the front axles do not rotate while in 2WD, then we wouldn't get this noise (if it is a CV joint) until 4WD engaged, thusly rotating the axles? Who says "thusly" anyway?

 

Anything effected by turning the wheels is in one way or another connected to your CV axles.

If it is the front differential it should be all the time

Remember on the lift the weight is off that can make a big difference.

Something hitting when the wheels are turned in the 4x4 mode.