Originally Posted by pimpernell

Just throwing out ideas, but I had the same issue with my 96 Kia Sportage gas engine. Bought the car brand new, and at about 59,000 miles, a noise as you described started to rear its ugly head. From my prior experience on gas engines, I knew that it could be either of two things. A piston slap, or a rod or main bearing. In my case, the noise only occurred within the first five minutes of starting the engine, and then diminished once the engine got up to temp. The car was still under warranty, and I left the car at the dealership overnight, and returned the next morning to be present for a cold startup. The noise was evident, and the dealer had his mechanic use an optical camera inserted into each cylinder, and it was evident that the number 3 cyl. wall was scored. Apparently, there was too much clearance between the piston skirt and the cylinder, and the noise was being caused by the excessive rocking motion of the piston skirt hitting the wall of the cylinder. As the engine warmed up, the clearance diminished, and became less noticeable. Over time, this condition would have gotten to a point where the engine would have to have been rebuilt or replaced. In my case, I was still 1,000 miles within the warranty period. Good luck !!