clunking front end

2000 2 wd astro 175000 km clunking at low speeds when turning lock to lock ie:backing in or out of a parking spot--mechanic had truck for 2 days- no play in any front end component-idlers good-no cracks in frame --he heard noise but unable to locate--any help greatly appreciated

Upper ball joints, if not greased regularly every 3,000 to 4,000 miles, will cause a "poping" sound under those circumstances. Grease all 12 of the fittings: Both upper and lower ball joints, all 4 tie rod ends, and 2 on each idler arm. Any one of those joints can check out good, but if it's dry, it will make noise.

I had a similar "popping" sound in my '96 Astro. It sounded like popping the lid on a tin can. I found a relaxed spot weld on the inner fender that when flexed would "pop". I went through the entire front-end also and only when I had a helper bounce the vehicle to reproduce the "pop" did I locate the true source of the noise. May be worth a look. By the way, all I had to do was pull the fender and drill out the spot welds and re-weld them.