2009 Chevrolet Corvette

REGARDING THE CYLINDER HEADS, I AM ONE OF HUNDREDS THAT EXPERIENCED INTAKE AND EXHAUST VALVES THAT WERE OUT OF SPECIFICATION DUE TO INADEQUATE CYLINDER HEAD DESIGN AND VALVE GUIDES. AS A RESULT, I NEEDED TO HAVE MY HEADS REPLACED WITH REBUILT HEADS AND NEW VALVE GUIDES. THE UPLOADED DOCUMENT HIGHLIGHTS THE MEASUREMENTS ON THE VALVES AS BEING OUT OF SPECIFICATION AFTER THEY WERE TESTED UPON REMOVAL FROM MY VEHICLE. ON AN ENGINE WITH ONLY 11,000 MILES AT THE TIME, THIS IS ALARMING. HUNDREDS OTHERS HAVE EXPERIENCED THE SAME DEFECT. THIS IS A SAFETY ISSUE AS WHEN A VALVE DROPS, IT FALLS INTO THE ENGINE HAVING THE EFFECT OF POTENTIALLY IMMEDIATELY SEIZING IT UP WHICH WOULD THEN CAUSE THE CAR TO LOCK THE REAR WHEELS AND LOSE CONTROL

ALTHOUGH MY CAR IS A 2009 IT ONLY HAS 300 MILES ON IT. THE ZO6 MODEL WHICH HAS THE "LS7 ENGINE HAS A KNOWN VALVE ISSUE WITH BOTH INTAKE AND EXHAUST BEING OUT OF SPEC AND WEARING RAPIDLY. I HAD A "WIGGLE TEST" DONE ON ALL MY VALVES. MORE THAN HALF OF THE 16 VALVES WERE OUT OF SPEC. IF THE ISSUE IS NOT CORRECT A VALVE WILL DROP AND A NEW ENGINE WILL BE REQUIRED.

I WAS CONCERNED ABOUT EXCESSIVE VALVE TRAIN NOISE AND AFTER READING SEVERAL CORVETTE FORUM THREADS AND SPEAKING TO NUMEROUS CHEVROLET MECHANICS ABOUT IMPROPERLY MACHINED HEADS BY GM'S SUPPLIER LINAMAR, AND THAT NUMEROUS VEHICLES HAVE HAD VALVES DROP AND RUIN THE ENGINES. THIS HAS HAPPENED ON COMPLETELY STOCK VEHICLES. PEOPLE WITH LESS THAN 20000 MILES HAVE LOST MOTORS. 88% OF THE CORVETTE FORUM MEMBERS WHO HAVE HAD THEIR CYLINDER HEADS TESTED FOR EXCESSIVE VALVE GUIDE WEAR, WERE OUT OF SERVICE SPECIFICATIONS. SOURCE: HTTP://WWW.CORVETTEFORUM.COM/FORUMS/...-REGISTRY.HTML GM NEEDS TO ISSUE A RECALL ON THIS ISSUE, THERE HAVE BEEN NUMEROUS ENGINE FAILURES AS A RESULT OF A DROPPED VALVE INTO A CYLINDER WHICH CAN CAUSE ACCIDENTS AND FIRES. GM IS VERY AWARE OF THIS ISSUE, BUT REFUSES TO DO ANYTHING ABOUT THIS HUGE SAFETY RISK TO DRIVERS, PASSENGERS, AND NEARBY VEHICLES IF THE ENGINE FAILS GOING DOWN THE ROAD. IF THE ENGINE FAILS DUE TO DROPPING A VALVE, THE ENGINE WILL IMMEDIATELY SHUT OFF, WHICH CUTS OFF POWER STEERING AND POWER BRAKING. THIS IS A VERY HUGE SAFETY CONCERN.

I WAS CONCERNED ABOUT EXCESSIVE VALVE TRAIN NOISE AND AFTER READING SEVERAL CORVETTE FORUM THREADS ABOUT IMPROPERLY MACHINED HEADS BY GM'S SUPPLIER LINAMAR, AND THAT NUMEROUS VEHICLES HAVE HAD VALVES DROP AND RUIN THE ENGINES, I TOOK MY CAR WITH 37,000 MILES ON IT TO COURTESY CHEVROLET / CADILLAC TO HAVE MY VALVE GUIDE CLEARANCE TESTED. I HAD (3) INTAKE VALVE GUIDES OUTSIDE OF SERVICE SPECIFICATIONS, (7) EXHAUST VALVE GUIDES OUTSIDE OF SERVICE SPECIFICATIONS, AND A COMBINATION OF (11) OTHER INTAKE AND EXHAUST VALVE GUIDES AT OR NEAR THE MAXIMUM OUTSIDE OF SERVICE SPECIFICATIONS. THE COST OF PROPER RE-MACHINING OF THE HEADS TO MAKE THE VALVE GUIDES CONCENTRIC, NEW INTAKE AND EXHAUST VALVE GUIDES INSTALLED, AS WELL AS NEW SEALS, VALVES, SPRINGS, ETC. IS SOMETHING I SIMPLY CANNOT AFFORD AT THE MOMENT WITH THE DOWNTURN OF THE OILFIELD INDUSTRY. PLEASE BEAR IN MIND, MY CAR HAD A REPLACEMENT LS7 ENGINE FROM A DROPPED EXHAUST VALVE BEFORE I OWNED IT, SO THIS HAS ALREADY HAPPENED TO MY CAR ONCE. IT OCCURRED AT 22XXX MILES, AND CAN HAVE THE GM DEALER PRINT A COPY OF THE RO LINE TO PROVE IT. THIS IS OCCURRING AT AN ALARMING RATE, BUT AFTER OUR WARRANTY PERIOD, WE THE CONSUMER ARE LEFT OUT TO DRY. 88% OF THE CORVETTE FORUM MEMBERS WHO HAVE HAD THEIR CYLINDER HEADS TESTED FOR EXCESSIVE VALVE GUIDE WEAR, WERE OUT OF SERVICE SPECIFICATIONS. SOURCE: HTTP://WWW.CORVETTEFORUM.COM/FORUMS/...-REGISTRY.HTML GM NEEDS TO ISSUE A RECALL ON THIS ISSUE, THERE HAVE BEEN NUMEROUS ENGINE FAILURES AS A RESULT OF A DROPPED VALVE INTO A CYLINDER WHICH CAN CAUSE ACCIDENTS AND FIRES. GM IS VERY AWARE OF THIS ISSUE, BUT REFUSES TO DO ANYTHING ABOUT THIS HUGE SAFETY RISK TO DRIVERS, PASSENGERS, AND NEARBY VEHICLES IF THE ENGINE FAILS GOING DOWN THE ROAD. PLEASE ASSIST US IN HAVING GM MAKE THIS RIGHT.

GM DENIES ANY SORT OF WIDE SPREAD ISSUE WITH RESPECT TO THE MANUFACTURING/ASSEMBLY OF THE CYLINDER HEADS FOR THE LS7 ENGINE. THERE HAVE BEEN NUMEROUS CATASTROPHIC ENGINE FAILURES AS A RESULT OF A BROKEN VALVE HEAD DROPPING INTO THE CYLINDER AND SUBSEQUENTLY BLOWING A HOLE THROUGH THE MOTOR, CAUSING FLUIDS TO LEAK ALL OVER THE ROAD, AND COMPLETE LOSS OF CONTROL OF THE VEHICLE. THE SYMPTOMS ARE PREMATURE VALVE GUIDE WEAR, WHICH EVENTUALLY BECOME SO WORN THAT THE VALVE CLOSES ON THE WRONG ANGLE TO THE SEAT, AND OFF BREAKS THE VALVE HEAD. THE ISSUE APPEARS TO BE POOR VALVE GUIDE TO VALVE SEAT CONCENTRICITY, WHICH LEADS TO PREMATURE VALVE GUIDE WEAR. MY 2009 Z06 CORVETTE AT ONLY 15,000 STREET DRIVEN MILES WAS INSPECTED BY A REPUTABLE THIRD PARTY REPAIR FACILITY, AND DISCOVERED THAT 14/16 VALVE GUIDES WERE BEYOND GM'S SERVICE LIMIT, AND THE REMAINING 2/16 WERE RIGHT AT THE LIMIT. THIS IS SOMETHING THAT SHOULDN'T OCCUR UNTIL 150,000 MILES AT LEAST...NOT 15,000. THERE NEEDS TO BE AN INVESTIGATION BEFORE MORE CATASTROPHIC FAILURES OCCUR. THERE ARE HUNDREDS IF NOT THOUSANDS OF DOCUMENTED OCCURRENCES.

THE LS7 ENGINE IS KNOWN TO HAVE BAD 2 PIECE EXHAUST VALVES THAT COME APART AND FALL INTO THE CYLINDER RESULTING IN A CATASTROPHIC ENGINE FAILURE THAT REQUIRES AN ENTIRE NEW ENGINE. THIS HAPPENED TO ME THIS PAST MARCH 2015. GM NEEDS TO ISSUE A RECALL ON THIS ISSUE, THERE HAVE BEEN NUMEROUS ENGINE FAILURES AS A RESULT OF A DROPPED VALVE INTO A CYLINDER WHICH CAN CAUSE ACCIDENTS AND FIRES. GM IS VERY AWARE OF THIS ISSUE, BUT REFUSES TO DO ANYTHING ABOUT THIS HUGE SAFETY RISK TO DRIVERS, PASSENGERS, AND NEARBY VEHICLES IF THE ENGINE FAILS GOING DOWN THE ROAD.

I WAS CONCERNED ABOUT EXCESSIVE VALVE TRAIN NOISE AND AFTER READING SEVERAL CORVETTE FORUM THREADS ABOUT IMPROPERLY MACHINED HEADS BY GM'S SUPPLIER LINAMAR, AND THAT NUMEROUS VEHICLES HAVE HAD VALVES DROP AND RUIN THE ENGINES, I TOOK MY CAR WITH 7800 MILES ON IT TO A CORVETTE SPECIALTY SHOP ( KATECH) TO HAVE MY VALVE GUIDE CLEARANCE TESTED. I HAD (5) INTAKE VALVE GUIDES OUTSIDE OF SERVICE SPECIFICATIONS, (4) EXHAUST VALVE GUIDES OUTSIDE OF SERVICE SPECIFICATIONS, AND A COMBINATION OF (3) OTHER INTAKE AND EXHAUST VALVE GUIDES AT OR NEAR THE MAXIMUM OUTSIDE OF SERVICE SPECIFICATIONS. THE CAR IS BEING REPAIRED WITH PROPER RE-MACHINING OF THE HEADS TO MAKE THE VALVE GUIDES CONCENTRIC, NEW INTAKE AND EXHAUST VALVE GUIDES INSTALLED, AS WELL AS NEW SEALS, VALVES, SPRINGS, ETC. 88% OF THE CORVETTE FORUM MEMBERS WHO HAVE HAD THEIR CYLINDER HEADS TESTED FOR EXCESSIVE VALVE GUIDE WEAR, WERE OUT OF SERVICE SPECIFICATIONS. SOURCE: HTTP://WWW.CORVETTEFORUM.COM/FORUMS/...-REGISTRY.HTML GM NEEDS TO ISSUE A RECALL ON THIS ISSUE, THERE HAVE BEEN NUMEROUS ENGINE FAILURES AS A RESULT OF A DROPPED VALVE INTO A CYLINDER WHICH CAN CAUSE ACCIDENTS AND FIRES. GM IS VERY AWARE OF THIS ISSUE, BUT REFUSES TO DO ANYTHING ABOUT THIS HUGE SAFETY RISK TO DRIVERS, PASSENGERS, AND NEARBY VEHICLES IF THE ENGINE FAILS GOING DOWN THE ROAD. HERE IS A LINK WITH THE GUIDE MEASUREMENTS IN IT. HTTP://WWW.CORVETTEFORUM.COM/FORUMS/C6-Z06-DISCUSSION/3608443-KATECH-STAGE-2-Z06-SN-74-A.HTML. *TR