My new Chevy truck developed a problem with clunking and a thumping in the steering wheel while gently turning on curves to the left or right at slow speeds, (25-35 MPH)...
Took it to the dealer, but they wanted me to wait a week for an appointment, so I took it over to get a rotation balance and alignment done just to eliminate the obvious.
Still have the problem, so I called another dealer to get the thing in and talked to one of there knowledgeable people there, he said "there is a known problem with the steering shaft seals going bad at around 20K and with warm summer temps all the grease runs out of the steering shaft".
What the heck you say? Me too! This is the truck my wife drives and for a while I didn't think anything of it, but now, knowing the shaft needed to be replaced, I am a little disappointed with myself for not finding out sooner...
Just thought you would want to know...
Big John