November 26, 2003
General Motors has been quietly buying back dozens of full-sized pickup trucks and SUVs after consumer complaints about knocking noises from the engine, consumer lawyers said.

GM confirmed that it has received "a small number of complaints" about excessive engine noise after cold starts of the Chevrolet Silverado and GMC Sierra pickups as well as the Chevrolet Tahoe and Suburban and the GMC Yukon and Yukon XL SUVs. Most of the affected models are from the 1999 to 2002 model years and are equipped with 4.8-liter, 5.3-liter and 6.0- liter V-8 engines.

The company has also bought back some 2002 Cadillac Escalade SUVs, according to lemon law attorneys who have handled the cases.

"I cannot believe that GMC ... would allow one of its Yukons to be on the road sounding like it has got a rod going out," said 2002 Yukon owner George of Wichita, Kansas. "I really enjoy the Yukon but absolutely hate the knocking of the engine. Almost everyone that hears it says something is definitely wrong and mentions a rod going out."

The company claims that the "only known effect" of the knocking is the sound. A spokeswoman said there is no damage to the engine. Some vehicle owners say the noise is caused by a condition known as "piston slap."

"I know that over time from speaking with the dealerships service manager I will experience power loss, poorer fuel economy and higher emissions," said 2002 Silverado owner Stephen of Peabody, Mass., in a complaint to

GM says it is handling consumer complaints on a "case-by-case" basis.

"They're got a lot of problems with their engines, for whatever reason," said attorney Brian Parker of Bingham Farms, Mich. Parker, who handles lemon law cases, said "numerous" consumers have won buybacks of their trucks and SUVs.

Another lawyer who handles lemon law cases in nine states said he knew of "more than 100" buybacks of Silverado and Sierra pickups alone.

The company claims it has fixed the problem with the faulty engines, which was first reported by the Detroit Free Press. A spokeswoman said it was caused by carbon buildup in the pistons for the 6.0 liter V8 engine in mid-model year 2002, and on the 4.8 liter and 5.3 liter V8 engines for the 2003 model year.

The engine knocking noise is not likely to spur a recall by the U.S. National Highway Transportation Safety Administration because it does not cause any safety problems.