Please forgive me if this is posted in the wrong spot. Please advise if so.

purchased 04 178K, took it to Firestone and after inspection they replaced tires, front left bearings, left and right tie rods, front brake pads (rotors were OK), flushed brake system, and aligned.

Drives fine in 2wd and shifts into 4wd hi and lo just fine (testing from neutral). Once in 4wd and begin driving a loud low "rubber-on-metal"/"rubber-on-rubber" noise. The noise goes away once back in 2wd. It makes the noise whether going straight or turning either direction.

The tires are standard size (235/70R15) if that helps.

I read all of the post about the 4wd actuator, but I don't think I have a problem there or it would have problems switching into 4wd altogether, right?

Anyway, what the hell is that noise and how do I make it stop?

Any help would be greatly appreciated.

Cheers!!

 

Sounds like the front axle isn't engaging properly. The front axle engagement is completely separate from the transfer case engagement. What is typically referred to as the 4wd actuator is what engages the front axle. On a 2004, the actuator itself will be located under the battery tray. You need to check the cable to make sure that it moves smoothly about 1/2" to 3/4" with some resistance from the return springs inside the front axle. If it does and locking it in place manually with a set of vice grips still results in the noise, then there is likely a problem inside the front axle with the engagement collar.

Check out this post for a break down of the reverse of your symptoms which has similar causes:
4wd Front Axle Clicking When in 2HI - Goes Away when in 4HI/4LO

Basically, if the teeth on the collar get ground down and close up, the collar will not engage on the teeth located on the passenger side extension axle.