NHTSA Complaint #10785256 — 2008 CHEVROLET CORVETTE

ENGINE KNOCK ON 6.2 LITER ENGINE. WHEN THE VEHICLE SITS A KNOCKING OCCURS IN THE ENGINE UPON STARTUP. IT IS NOT A LIFTER KNOCK, BUT A KNOCK DEEPER IN THE ENGINE GM HAS NOTED THE PROBLEM AND MADE MULTIPLE REPAIRS (6+) CAM SHAFT CHANGED BUT NO LIFTERS. THOUGHT THIS WAS ODD AS THE WEARING SURFACES ARE NOW DISSIMILAR .GM SAID THIS IS ALL THEY AUTHORIZED. KNOCK STILL PRESENT GM THEN REMOVED UPPER END OF ENGINE. NOTED EXTREME CARBON BUILD UP ON MULTIPLE PISTONS. ONE PISTON HAD SO MUCH BUILDING APPARENTLY CLOSE TO VALVES HITTING. GM TECH ADVISED ENGINE REPLACEMENT, GM AUTHORIZED CLEANING OF PISTONS: GUESS WHAT, KNOCK STILL PRESENT THE KNOCKING IS A PISTON OR LOWER END KNOCK. SIMILAR TO WRIST PINS OR ROD BEARING CAPS OR BEARINGS. WHEN KNOCKING OCCURS ENGINE IS ROUGH AND PULSATES. TIME RANGES FROM 30 SECONDS TO COUPLE OF MINUTES AFTER MULTIPLE GM REPAIRS KNOCK IS STILL PRESENT, NOTICED ENGINE PERFORMANCE IS NOT THE SAME AND WITH LACK OF STABILITY FUEL ECONOMY HAS DROPPED