Thousands of truck owners are complaining to General Motors about an irritating noise in their engines, Call 4 Action reporter Susan Koeppen says.

A "knock" is being reported in models like the GMC Yukon and the Chevrolet Silverado, mostly between 1999 and 2002. Owners say the problem is a loud sound of pistons hitting the cylinders.

One owner, Aaron Trapuzzano, was given a 100,000-mile warranty when he voiced his complaint to GM. Now, he's taking action under Pennsylvania's Lemon Law.

GM officials say carbon and the amount of clearance between the piston and the cylinder wall are the primary causes of the knocking. Owners who hear loud and continuing engine knocking should take the vehicle to an authorized GM dealer for inspection and repairs.

Click here to learn more about this problem at pistonslap.com.