On our way home today, my '97 S10 Blazer started whining, or humming, it sounded like a big 4 wheel drive truck going down the road. It has never done this before, and it didn't do it the entire way home. It started, out of the blue, on the expressway, but when I was coming to a stop, at about 15mph, it just stopped making the noise (abruptly stopped). It did this twice, stopped both times when I got down to about 15mph. The slower I went, the louder it got.

We checked all the tires, they're good. I moved the steering wheel back and forth, it's not the power steering. I kicked it down, and there was no change in the noise. It didn't seem to be coming from the motor or transmission. All the gauges were normal. It actually sounded like it was coming from the front passenger side, but it's hard to say. We thought it might be a wheel bearing, but it didn't make the noise the whole time.

Does anyone have any thoughts, we don't have a clue...

 

More than likely a bearing.. they don't always make noise loud enough to hear, but you'll notice at higher speeds how bad one is. Back a few months ago before I quit NAPA due to personal differences *cough* both of the Aveos had crap bearing and you only really heard them when going 50+

 

Sounds like your wheel bearing or hub assembly depending on 2wd or 4wd. Could also be a bearing in your front differential output shaft. I have a similar problem in my truck which during my investigation found my front differential was dry so I get to buy a new one. If you jack up the front end grab the tire and see if there is any play in the wheel bearing. While its up in the air check the front differential gear oil level. My 2 cents.

 

I'm assuming you have a 4wd blazer. If so it could be a stuck vacuum switch on the transfer case . When mine stuck it would sould like I was running over rumble strips with the right front tire. The switch will stick allowing vacuum to the front differential. If you own a 2wd this would not apply to your vehicle.

 

I had a similar (if not the same problem) for about a year til the other day when I finally replaced it. Front right wheel bearing assembly went bad on it and ended up just swapping it out for a new one. The entire procedure is about as bad as doing the rotors and shouldn't take too long to do if you do it yourself.

Anyway, I couldn't go faster than 30 before this monster truck sound came out of my car and it was just annoying. My opinion, if you have a mechanic, have him take a quick look or drive and ask what he thinks the problem is, but more than likely it's the wheel bearing assembly