First time poster. I have a 99 LS 4WD. I have a whirring noise coming from the left front. I can feel it under my feet as well. When I get to about 45 and let off the gas, it whines. My first thought was wheel bearing. So I put it on the lift and checked. No 12-6 movement. Checked the 4wd actuator and its good. Any ideas? Could it possibly be the wheel bearing even with no play??

 

Also checked front diff fluid. It was super low so I added some, coukd something be wrecked in there causing the noise?

 

If you think there's a problem with the left front bearing, find a road that curves to the left. If you're traveling at speed and getting the noise, listen to see of the noise changes as you go around a left curve and unload the weight on the L.F. bearing. If the noise goes away, then you probably have a bad bearing or related part. If there is no change, it's probably located somewhere else.

Personally, I'd try the curve an if that doesn't do anything, rotate the front tires to the rear and see of the noise changes location. If the noise now comes from the back, you've got a bum tire.

As for the humming, maybe your Blazer doesn't know the words, and the whining is because it's frustrated because of it.

 

x2 &lol...

 

Pcv valve? Cheap to try. 4wd switch? If you don't mind throwing a little money at it try those things and a hub and new axle ,(rockauto.com) get all that for less then 150_200