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.

 

[rtbrjason]

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.

Just living with it?

 

[ExplorerTom]

Just living with it?

Nope. Brown Wire Mod accomplishes the same thing without having to replace the fuse.

I'm either RWD or 4wd. I've never been a fan of a4wd.

 

[rtbrjason]

Nope. Brown Wire Mod accomplishes the same thing without having to replace the fuse.

I'm either RWD or 4wd. I've never been a fan of a4wd.

Okay. Yeah the brown wire mod works a bit differently I think. I believe you can still switch to 4x4 while a4wd is completely off, where I need to turn a4wd on before I can switch to 4x4.

 

[ExplorerTom]

The only way it works different is you have to remove/replace the fuse to get your a4wd and all I need to do is flip a switch.

Or I can leave the switch off and have RWD and 4wd (no a4wd).

I started out by pulling my fuse to diagnose what was going on. Glad I did. Won't go back.

 

[rtbrjason]

The switch I rigged up is in place of the fuse. Switch on is like putting the fuse back in. Switch off is like fuse removed. The switch is in the cabin and be turned on or off while driving.

With the switch off though, there is not only no a4wd, but the 4x4 high and low aren’t selectable.

Maybe I should repurpose the switch to turn the brown wire on/off and put the fuse back in place. I would like to know and repair the source of the noise though.

 

[mbtech2003]

My 05 has a similar issue, the carrier bearings in the front diff were bad. Just swap in a used diff. You can get a front diff for under $200. If that’s what is wrong with yours

 

[Jon1999expo]

My 99 does the same thing, I pulled the fuse and stopped all front-end noise. I was told the a4wd causes that binding and noise if all 4 of your tires are not a exact match in the wear pattern and cause a difference in rotational speed which in return triggers the a4wd to act up. Our 4x4 systems are very sensitive to tire wear variances. Using mismatch tires are the issue even if they are the same size.

 

[rtbrjason]

I just did 4 new winterforce tires about 500 miles or so ago. It’s a fairly new noise. Since I had the a4wd off all summer, and rarely drive it in the summer, I don’t know exactly when it started unfortunately. I do know it wasn’t there last winter though.

 

[1955moose]

It's just an educated guess on my end, but I would think your tires would have acted up sooner, if their was an issue due to tread. I just installed a set of ohtsu street tires on my 2000, and theirs nary a noise from my awd. Bearing noises are easy, or a pain in butt to figure out. Sometimes it's real obvious, and progresses with speed, others not so much. I repaired a broken shift shaft and spring on a 87 Harley big twin a few years back. I replaced the broken shifting parts, carefully spun each roller bearing, found no noise, or excessive play. But when I had it back together for the road test, you should have heard the rumble it made. That's why a safe bet is to replace any bearings when apart. If your Suv is getting up in mileage, it maybe starting to fail. Let us know once you get it narrowed down.

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