Humming noise

[9COOP5]

The best way to describe the noise is to say it sounds like a humming noise in my ‘02 XLS Explorer, not a grind, and near the front towards the middle of the truck. I was going about 30 mph and could really notice when I was able to cost a bit down a slight hill, or when I accelerate and then let off the gas.

 

[loosenut349]

Is your Explorer two wheel drive or four wheel drive? From what you described it sounds like the differential is humming and the sound is being transmitted through the driveshaft to make it seem like the humming is in the front.

 

[9COOP5]

Two wheel drive

 

[loosenut349]

OK, does the noise get higher pitched as you accelerate and then slow down when you let off the gas? If you rock the steering wheel side to side, does the noise change or go away when the steering wheel is in one position and get worse when in the other position?
This seems to be a bearing noise but I am not sure which one, that is why i am asking all the questions.

 

[9COOP5]

Ok I will check more about what you said tomorrow and let you know.

 

[CarlosHRNYC]

Like loosenut says. Probably a wheel bearing. Not a hard job to do. I did my front passenger side 2 years ago when I got that "hum" as you describe.

 

[loosenut349]

Ok I will check more about what you said tomorrow and let you know.

There is one thing I forgot to mention, don't drive too fast when you are rocking the steering wheel, about thirty mph should be good. And do it on a lightly traveled road.

 

[loosenut349]

Did you try what I mentioned?

 

[9COOP5]

Did you try what I mentioned?

No I have not tried yet but will tomorrow. I have not driven the truck since but will let you know. And thanks for the info again.

 

[loosenut349]

No I have not tried yet but will tomorrow. I have not driven the truck since but will let you know. And thanks for the info again.

You're welcome.

 

[9COOP5]

I did not hear the humming noise when I rocked the steering wheel back and forth. I did hear the noise sometimes during 30 to 60 mph, not really at higher speeds. When I accelerate and let off the gas I can here it.

 

[loosenut349]

OK, this is sounding like the differential is making noise on the coast side of the ring gear.
You might want to check the lube level, it could be causing the noise if it is low.
It is easy to check, jack the truck up so you can get under it, don't forget to use jack stands, remove the plug on the passenger side of the diff. it is a 3/8 square so you can use a ratchet, after removing the plug, put your little finger into the hole up to the first knuckle, there should be gear lube on your finger about half way to the first knuckle. If not then it is low and you need to add some. I believe the right weight is 85-120 synthetic. If after filling the diff, the noise is still there, the diff may be worn and have to be repaired or replaced.

 

[Drewmcg]

Don't rule out rear driveshaft u-joint. Had my replaced on 2wd 190k 2002 XLS and it helped a bit. Also, how good are your tires? And what's the mileage on this truck?

If it's a wheel bearing, it will get progressively worse, and become a sickening grinding . . . . I hate that sound.

 

[9COOP5]

184k on the truck, tires need changed soon!

 

[Drewmcg]

bad tires can add to road noise.

 

[loosenut349]

Drewmcg is right, I had C load tires on the back of my Aerostar and they were noisy as hell.

 

[9COOP5]

The left rear hub bearing is bad, it even seemed to have gotten much louder over the last two weeks as I didn’t drive it. Getting replaced for $269.

 

[Drewmcg]

Glad you figured it out. I haven't replaced my rears yet, but carry a spare rear bearing in back of the truck, under the floor panel, in case it goes out on a long trip.