Hey guys,

I've been hearing a noise coming from the right side passenger front wheel area, it sounds a lot like a grind or hum once you reach 50 mph and picks up tone as you drive faster, its faint but obvious and drives me crazy, haha. The other three sides sound fine, just the pass front makes noise. Tires are like new with only 5k on them and are a a/t tire. Vehicle is a year 2000 and its 4x4 with only 69,000 miles.

Things I've noticed:
-It gets louder the longer you drive the vehicle, almost silent for the first five minutes.
-loudest between 50 and 56 mph but you cant hear it much or at all anywhere below or above them speeds.
-completely goes away when its in 4wd....

So I figured wheel bearing and replaced it last night with a premium part, but the noise is still there. The install went smooth and I know its done right.
I did notice when I turned the hubs the axles spun as well, is this normal for auto hubs? Or should they be coasting like lock outs ( sorry I'm more familiar with lockout hubs)

So can anyone give me some ideas based on what I said or suggest anything new to look into?

 

swap sides with the tire. see if it changes?

 

forgot to add the noise completely goes away when its in 4x4.

 

Tech Article (DIY) Section to the rescue:
4wd Front Axle Clicking When in 2HI - Goes Away when in 4HI/4LO

 

Ok I just checked the actuator. From the looks of it I pulled the side rear hose off ( not the front which looks like a cable), but from what I could tell there was no vacuum; but it was kinda hard to tell since the fan was blowing in the area I was trying to check. Is the front line a cable or vac line? its hard to tell and I didn't want to pull on it until I know for sure. Or is there a different way to check?

 

That is a cable that runs to the front axle engagement mechanism in the front axle. It should move by hand 1/2" to 3/4". If it doesn't move that far or not at all, then the cable is frozen and either needs to be lubricated or replaced.

 

Ok I'll take the battery out again tomorrow and double check to make sure the cable's working properly.

So with these things in minds what else could be causing this annoying hum?

 

If the cable is moving freely, the problem could be a leaking vacuum switch or solenoid depending on whether you have the NV236 (4-button switch in the dash w/ Auto4wd) transfer case or the NV233 (3-button switch in the dash). There should be no vacuum to the actuator under the battery with the engine running and the transfer case in 2HI and the line at the actuator should not hold vacuum either as it should be vented by the switch/solenoid if plumbed properly.

It is very common for the vacuum switch on the NV233 transfer case to go bad in a variety of ways; one of which is leaking vacuum when not engaged.

As far as what else could be responsible for this noise, I doubt there really is anything else that could produce the same symptoms. The fact that it goes away completely once 4wd is engaged eliminates a lot of the other possibilities.