Is there a good way to check if the idler arm is doing/not doing its job? I'm wondering if that's the thing doing all the rat-tat-tat-tating?

 

Get someone to turn the wheel side to side while someone looks under the vehicle at it. I usually hold it while someone turns the wheel side to side. Then you can feel if there is play.

 

It should only (well mostly) swing in an arc with no up-down motion.

 

With enough slack in the idler arm to rattle you prob would have a problem with the vehicle wandering and ducking and diving while driving down the road.

 

I actually made a video about this a while back they 2nd time I changed mine on my 04

 

Nice video.

When I replaced my idler arm, I could get much more deflection (vertical) than you did with both tires off the ground which would indicate just how loose it was.

There are two good replacement idler arms; Proforge and Moog. Did you use the Moog part?

There is also a way to adapt a 1-ton truck idler arm to a Blazer. The adapter cost $200 though! However, if the last idler arm fails, I'll likely go for the 1-ton upgraded one.

P.S. Dude, your undercarriage is spotless! I wish mine when clean looked as good as your when "dirty". LOL

 

Blazin, sorry I did not see this and thank you for it.. I think I have more deflection than you did but the steering is pretty steady so maybe not, I'll check it out.
I don't think that is causing the bonka-bonka-bonka-bonka when I drive over a rough street, though, do you? But if it moves like you say it probably needs replacing

 

On edit, I went ahead and replaced the idler arm and will write how the operation went in another post. The bonka-bonka turned out to be a loose hood hinge bolt.