This is cupping http://www.berniescarcarecenter.com/...ed+edges+3.jpg
un-even wear of the tread, basically the tire is not sitting flat to the ground, thus causing un-wear of the tread

You idler arm is bad, it is a common problem with s-series trucks, if your going to replace it got the brand Moog, check amazon or Rockauto and don't forget to Google for rock auto discount codes.

Another good start would be to swap the front wheels to the rear but keep them on the same side to make it easier to identify a bad tire or wheel.

 

Thanks kar im going to have to look into this tomorrow morning. Ill keep you guys updated. Thanks again

 

Alright checked out the tires they seem fine switched them to the back noise is still in the front. Anyother ideas would help.

 

Have you checked for loose parts on the front that could be getting buffeted but the wind as you speed up? ie plastic valance under the bumper or skid plate...

 

Yes iv checked them maybe the hood tho. What do you think about it bing the ujoints? But when putting ir into gear it dont pop or anythinf

 

Is the thumping noise constant, or comes and goes? Does it change when you're speeding up? If it's a thump/rattle type noise that isn't constant, and you're suspecting the hood, check the hood hinges. There was a service bullitin recall to install a spring washer on the hood hinges in 2nd gen Blazers because they would start to rattle. An easy test or temporary fix for this is to stuff a piece of cloth under the hood hinge, and go for a drive. If the thumping is gone there's your culprit.

 

Its constant seema to speed up as i get faster. Checked the hood today no movement. Not with engine speed more like the rotation of the tire to me at least. Ugh im going crazy thought it would be something obvious.

 

How about a wheel bearing? CV joint gone bad? Front dif rubber mount? (I'm grasping now) Does it change in 4WD?

 

Same in 4wd. Just replaced both cv joints and all 4 ball joints. Not 100 about the wheel bearing but ov had one go before doesnt seem the same when i turn its the same constant thumping no difference. Chwcked the u joints they are fine. Any other ideas ill get out there n check till i figure this crap out

 

Is this a thumping sound, like thumpthumpthumpthump, or more of a growl, grinding, hum type sound you would hear from a worn hub? I'm kind of confused by your description. If it's a growling sound it could even by your front differential. Have you checked to make sure it has fluid in it?

If it is a thumping sound like you originally described, I'd be looking for loose material like an inner fender, air dam, bug deflector, the oil filter door on the skid plate, etc. It could even be your block heater cord if you're somewhere that those are necessary. My wife had her's out too far once and it was flapping around in the wind causing a thumping sound. Good luck tracking it down.