Bearing noise in a4wd?

[rtbrjason]

I’m noticing a noise similar in sound to a bad wheel bearing in a4wd. Mostly noticeable at lower speeds under some load. I have a switch rigged to kill fuse 104 (awd) under the hood. When I turn the switch off, the noise goes away completely, so I’m certain it’s not a wheel bearing. It does sound like it’s coming from the front. Hoping it’s not a bad front differential. A4wd as well as 4x4 still seem to be working fine. Any ideas?

 

[ExplorerTom]

The auto is no longer auto- it's full time. The noise you're hearing is just slight driveline binding. Keep the switch off.

 

[rtbrjason]

Not sure what you’re saying. This is a new noise that didn’t exist last year. The switch is on currently due to largely snow covered roads in upstate ny. I do keep the switch off when the roads are clean/dry.

 

[rtbrjason]

The switch I’m talking about just cuts power to fuse 104 so that the a4wd is unable to send much power to the front wheels. When the switch is on, the truck behaves like stock where the a4wd functions as intended and 4x4 hi/lo are selectable. So when the switch is on and the truck is in a4wd I’m hearing the noise. When Turning my switch off (fuse 104 removed), the noise goes away completely.

I did do a fluid change on both the transfer case and front differential. Both fluids that came out were clean though and the new fluid didn’t change the noise.

 

[1955moose]

When you did your fluid changes, did you add the additive from the dealer. Very important on front differential.

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[rtbrjason]

When you did your fluid changes, did you add the additive from the dealer. Very important on front differential.

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No. This is the 3rd fluid change I’ve done too. I wasn’t aware of any additives required for the front differential. I thought there was only an additive for the rear, and then only if you had limited slip?

 

[1955moose]

I think you're right on that. I could have swore a few months back some of our guys were talking about using something from Ford. Guys did any of you use it, or was it just the rear!

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[1955moose]

I reread your original post. You stated you rigged a switch to shut off your awd, why? A bad bearing with get worse with speed. Your problem leans towards a sensor or something that's load dependent. You didn't mention were their any codes

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[rtbrjason]

I reread your original post. You stated you rigged a switch to shut off your awd, why? A bad bearing with get worse with speed. Your problem leans towards a sensor or something that's load dependent. You didn't mention were their any codes

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No codes. The switch was setup so I didn’t have to pull the fuse to keep the transfer case from automatically sending power to the front all summer. It would have been nice if Ford had left the 2wd as a selectable mode, but my 99 only has a4wd, 4x4 hi and low on the selector dial. Turning the switch off is essentially as close as I can get to 2wd, and it only took a short time to wire in.

 

[ExplorerTom]

Same thing happened with mine.

Noise with fuse 104 in place. No noise with it pulled.

I also don't notice the noise with it in 4hi.