Loud roaring noise in front end of 2003 Blazer 4WD 2 door from 40 to 60 mph. No clicking, clunking, or other problems. Tires are wearing evenly. Alignment is good. No pulling left or right. I am starting to feel a very slight vibration in the steering wheel. 96,500 miles. I searched forum and find the 'wheel hub bearings' are the most common answer. However I think it could be the front diff., the transfer case, the CV joints, or the front tires. I hate to replace the wheel hubs and find it is something else. How can I test or eliminate these items and determine the cause?

 

try driving it and lightly swerving the vehicle back and forth when you hear the noise. if its a wheel bearing the sound will change tone when you are veering left or right. which ever way you are turning if it gets louder it will be the opposite side, so if you veer left and it gets louder its your right front wheel bearing.

 

I have tried that swerving in the past and the change in tone was so subtle, it was was hard to say if the change was due to the normal tire noise or the pressure on the bearings. I will try that again to see if the difference is more noticible. The 'roaring noise' is certainly getting louder and more noticible driving in a straight line on hwy driving.

 

With the Blazer on a smooth asphalt road in the rain, when I turned left at 50 mph, it got somewhat louder. Not a big difference, but noticably louder. Right veer , no difference in roaring. So this test would indicate a bad right front hub bearing. Correct?

 

yeah in theory thats how that works, when you veer to the left you are putting more weight and sideways force out that right wheel bearing. but its not only like 95% accurate. theres been a few times i could have swore it was a certain bearing but replaced the wrong one

another ways to test them is get them spinning in 4x4 and listen to them with a stehoscope. or remove the axle out of the bearing and take the brakes off and spin it, if it feels weird or make noise then its bad but of course that takes a bit of work

 

I like the idea of spinning them in 4WD and listening to each wheel hub, transfer case, and front diff. You should also be able to see a bad U--joint. I have enough jack stands to do that but feel uneasy doing this on my unpaved and uneven driveway. It would be much safer on a lift. I have read other posts re: and the 'partial engagement of the transfer case' comes up as a possible source of noise in the 40-60 mph range. BTW acceleration or decel. or coasting makes no diff. in the noise level.

 

With all the Hub tests, except the 'swerve test', showing negative, I was uncertain the problem was in the Hub bearing. I hated spending 141.00 on a Moog bearing and a 20.00 36 mm socket plus other things like loctite and anti-seize it was getting expensive for not a sure cure! But the loud noise was getting louder and lower in speed range- now starting at 35 mph! I had to do something so I went ahead. I got center hub nut off and the three -18 mm bolts holding it on, but it was stuck firmly to the splined driveshaft. I needed a hub puller and didn't own one and my only trans was the Blazer. I rented two and they were the wrong size. I finally bought a flimsy HFT set and it worked. I cleaned the spindle up and put it back together. I had an old style 'bar' Torque wrench and it was hard to read in this application. You need a 'click' style torque wrench to torque the 3 Hub bolts, the two caliper bolts and the center hub bolt. Plus the lug nuts. Oh, yes, I kept spinning the old hub by hand to see if it was grinding or making any noise. None, it was silent. There was no play in it either. At that point, I felt I had made a diagnostic mistake , but I was too far along to go back. I installed the shiny new Moog wheel hub and was pleased when I first road tested it. At a speed of 40 mph, no noise. Up to 60 mph, still no noise or vibration through the steering wheel. The point is this: all the tests such as the '3 o'clock and 9 o'clock shake side to side may not show a bad bearing. The spin by hand test is invalid because the noise is at 40 mph, and you can't spin it by hand that fast. Thanks for all who responded to my requests for information. If you do this job, be sure to look and the 1A Auto video's Part I and part II. Other vid's on Youtube may be helpful.