Hi there... The noise is there as soon as the truck moves, 1 to 2 mph you hear it... But no sound in reverse... If it is a wheel hub, wouldn't it make the sound in reverse as well as in drive? It sounds like it is coming from like dead center of the axle, not toward either tire, but the center...I am starting to think it has something to do with the transfer case somehow...

 

I had to go back and reread this thread and ponder. At first you describe it as a humming thumping sound. Louder at lower speeds. You replaced drivers side front wheel bearings and then said noise only in 2 hi. I asked for a few more tests/feedback and you say it does not do it in reverse. Your thinking transfer case. Above it also appears to keep pace with the speed your going, faster speed, quicker thumping.

When you rotated tires did this thumping sound change in location like toward rear or front? At 1-2 mph obviously nothing is rotating very fast vs say at 35mph or 70mph hyway speeds. It almost seems like your describing a flat spot on a tire. What is the cadence of this thump- ie: beats per minute when moving under 5mph? No, you don’t have to use a stop watch but describe so we can have an idea- does it seem to match about 1 revolution of the tire per thump or more like a fast rock and roll 1-2-3-4 thing. Never did say if when in neutral coasting if still does this nor if you put truck on jack stands and started and put just in drive if noise there without the Blazer in motion. Do you get any feeling from this thump in steering wheel with your hands or say feel it with your feet on floor or just hear it?

I know I’m asking for a lot of detail but your description is all we have to go on so figure I would treat this like I treat my wife, get her to be detailed as possible so it can be fixed right.

 

Here is the latest situation... I put the front end up on jack stands and spun the front tires by hand and no sound at all... Went for a quick drive and there it is again. The most accurate way I can say it is it a "humming" sound, not like a rubbing or thumping or grinding sound but humming. I put the thing in 4hi or 4lo and no sound... 2hi and bam, there it is. I inspected all 4 tires and see no evidence of a flat spot or a rock, nail, screw ect in the tread... Started out only in 2hi then all 3 ranges, now back to just 2hi. Only moving forward at any speed but no sound in reverse...

 

 

That's what I am thinking... I am just gonna get it in the shop and be done with it... The thing that bugs the heck out of me though is if a gear, metal, teeth ect is worn down why only make the noise going forward but not backward? In 2hi the front axle is spinning freely if I am not mistaken but no sound in 4hi when it locks in... Once this stupid thing is fixed I will report back for sure!

 

Hmm - 5 cents of thought.

Have you changed tires?

What tires are you running?

 

I have rotated the tires, I actually do it every 3000 miles when i give her an oil change... The tires I have still have a ton of meat on them after a little over 3 years and are wearing like a dream I have Good Year Wranglers all terrain, P235 75 R15s...

 

I am now beyond confused... I drove the Blazer to take my wife her cell phone, she forgot it this morning rushing out the door, and the thing made no sound at all! I was gonna put it in the shop this Friday... I thought, am I now immune to the sound? No, window even down and no humming sound. I even went through the range, 4hi ect... Nothing! Does a wheel hub have a " break in period " ? I just replaced the driver side... I know this is getting old but what the heck??? Sorry, but this has me wanting to pull my hair out! I am NOT a mechanic by any means, but I DO know enough about things and they just don't fix themselves... Thanks...

 

No, no break in period for wheel bearings

Sounds like it's fixed! Good job! Lol