I have a 2001 Tahoe with 65,000 miles on the 5.3L motor. For the last year the engine has had a nock, similar to piston slap, upon startup. It only last for 15-20 seconds then goes away completely. The nock is only evident if the truck has sat for more than a day. Originally I thought I had spun a bearing but if that was true I think it would have thrown a rod by now considering the fact that this has been going on for more than 15,000 miles. My tahoe is used from everything between a grocery getter, to a trailer puller in the Colorado Rockies. Has anyone else had a similar experience? Any ideas what may be my problem? Thanks again for your help!

Respectfully,

Bill Rudel

 

Sounds like you have a lifter that is bleeding down, a bad lifter will take a few seconds to fill back up with oil after they have sat for a while.
Piston slap generally doesn't go away.

Welcome.

Dave