NHTSA Complaint #717036 — 1991 CHEVROLET LUMINA

EXHAUST VALVES ARE STICKING, CAUSING THE TIMING BELT TO SLIP. WE HAVE REPLACED THE BELT AND THE PROBLEM IMMEDIATELY RECURRED. GM HAS BEEN AWARE OF THE PROBLEM FOR YEARS, BUT HAS BEEN FAIRLY QUIET ABOUT RESOLVING IT. THEY PRODUCED A NUMBER OF 3.4 ENGINES WITHOUT CHROME PLATED EXHAUST VALVES, AND THE SOFTER VALVES DISTORTING AND STICK, CAUSING THE ENGINE TO JUMP TIMING. THIS IS A SOPHISTICATED DUAL OVERHEAD CAM V-6 AND TOLERANCES ARE CRITICAL. GM ISSUED A DIRECTIVE TO REPLACE THE CYLINDER HEADS ON THE AFFECTED ENGINES, HOWEVER OURS WAS NOT INCLUDED IN THE RECALL, EVEN THOUGH IT WAS BUILT IN THE PLANT THAT PRODUCED THE ENGINES AND IS IN LINE WITH THE SEQUENCE OF ID NUMBERS. GENERAL MOTORS IS DISAVOWING THE PROBLEM, EVEN THOUGH IT IS A KNOWN DEFECT. THEY HAVE REPLACED A NUMBER OF CYLINDER HEADS AND EXHAUST VALVES, AND I BELIEVE THEY SHOULD ACKNOWLEGE THEIR ERROR IN OUR CAR AND REPAIR OUR ENGINE. BECAUSE OF THE SOFT EXHAUST VALVES, THERE IS NO ALTERNATIVE BUT TO MAKE MAJOR REPAIRS, ALL DUE TO IMPROPER MANUFACTURING. *AK