2018 Silverado clunking from front

Ashton Goodrich · June 9, 2020

Hi all - I have a 2018 Silverado LTZ 4x4 6.2L, and only "mod" is that I've removed the lift blocks from rear.

Truck now has 25,000 miles on it, and the clunk all started when I'd pull up to my garage and stop and then have to back up to straighten up to pull in. When stopping I'd get a soft pop or clunk that I could feel in floorboard. That's about the only time I could feel or hear it. As time has gone on though, I notice slow speed pops or clunks, typically in parking lots with uneven surfaces. I took to the dealer this last week and they performed the TSB that involved the retorque of the crossmember bolts and the control arm bolts/nuts. I'm assuming they did both....

So I go to pick up truck after the tech has driven and confirmed no popping - and as I'm backing out from dealer - yes, a pop....it's Friday around 4:30 p.m., so I just head home. The next day I drive the truck a few places and go in parking lots, etc, and it's popping like popcorn - clunking at low speeds....So I commit to going back to dealer this morning. And of COURSE, on the test drive with the tech, can't get it to do it.

I didn't note the humidity on Saturday with all of the popping, but today was fairly humid - not sure if that has anything to do with this, but it's driving me crazy!!!! And the fact that it would not pop this morning and now I look like "that guy" - I apologized to the tech for wasting his time, and said if I hear it again I'll come right up.

My first question is - what's the size of the control arm nuts and the rear leaf nuts.

Second - any ideas? I wish I could record the sound or figure this out.....

Eddie 70 · June 9, 2020

Mine was making a popping noise, so I checked the ball joints by jacking the front wheels off the ground and pried up on the tires with long pry bar. The tire moved up a touch so I assumed bad ball joints. I ordered loaded upper control arms for both sides. When the new arms arrived, I jacked the truck up and took the front tire off. I put my wrench on the bolts for the upper control arm and they were loose. That was where my clunking was coming from. I changed the upper control arms anyway and had an alignment done.

YMMV, this was my truck. Also check that the upper nut for the strut is tight. I found that loose after getting new struts.