Front End

I have a 99 4x4 149,000 miles. I have a humming noise coming from the front end when driving on the freeway 40 mph or faster. (louder when going faster, quiter when slowing) I've read others posts to humming front ends and its been the bearrings and they were able to tell which one by turning the wheel to the left or right and the noise would go away. I've tried that and the noise does not go away when I turn the wheel. We are 98% certin that the noise is coming from the drivers side. We have had this truck for alomst a year and a half. We havent driven much on the freeway so when we heard it several days ago we dont know how long the part has been bad for. Could mabey the bearring just be too gone for the turning of the wheel test to work. Or is it something else?

Also, There is a loud clunking noise when breaking. We can feel it through the steering wheel sometimes and most of the time feel it through the floor board. It's also coming from the drivers side. When breaking VERY hard it can be heard and felt. When close to a full stop and we press the breaks harder making the truck come to a full complete stop it can be heard and felt again. It makes a clunking noise sometimes, poping sound sometimes, and sometimes it makes both sounds. can anyone help that had this happen to them so i know where to start looking or what to fix first.

I'm no expert but it sounds like your 4 wheel drive might be partially engaged. I'm assuming it's a 4x4. Maybe someone else who's experienced with 4 wheel drive can chime in.

edit: I see it's a 4x4. That could be the clunking and humming you hear.

Does your 4x4 work? i agree with srbianats, take a look at your 4x4 system first. Engage it and see if the noise goes away. How long has it been sitting? Is there brake pedal pulse when you step on the brakes? Does it clunk only when you hit the brakes, turning, or hitting a bump? When were the brakes last serviced? Could be that it needs brake service. Take a close look at your front end, make sure everything is tight and nothing is loose.

Havent looked at the breaks yet. Yes the 4x4 works properly. Noise still there when 4x4 engaged. If its a big enough bump it will make the noise and does it when breaking. There is a very slight pulse form warping rotors.

Could be the transfer case??? Like it was said partially engaged 4 wheel drive. Could be a loose caliper. Could be the clunk hood fix BlazerLT did a write up on. Kind of hard to narrow this one down.

I have a 99 Blazer 4x4 also with 130,000. I just went through this two weeks ago. The driver's side wheel bearing went out. It is an assembly that includes your ABS sensor ($150). When working on this we realized that the upper and lower ball joints, idler arm, and pitman arm were also shot. I ended up doing all the ball joints on both sides. I then realized the shocks were shot too. I talked with a lot of people about the wheel bearing, it is almost always the driver's side. There are several thread on this topic here.
Also, if you are doing this work yourself, it takes a 36mm socket and puller to get the bearing assembly off.