Technical Service Bulletin PIP5331B — 2013 CHEVROLET IMPALA

This Preliminary Information communication provides information to the technician that some vehicles may have rattle, tick, or knock type noise. If there are any drivability concerns they should be addressed prior to the following diagnostic progression. Technician will take a sound file or video with sound of the noise prior to dis-assembly. Technician may find this noise hard to isolate to one area in the engine. There are four different steps to take to diagnosis the concern. Technician will perform injector diagnosis to ensure there are no leaking injectors causing a noise due to excessive fuel in any one cylinder. Replace any out of specification injectors the reevaluate for the noise. Technician will remove the intake manifold and visually inspect for excessive carbon on the intake valve stems and top of the valve causing noise. If carbon is present then follow the latest version of PIP5029 to clean the valves or replace heads as needed. Technician will remove the cam cover of the affected bank (both if needed) to inspect for soft or spongy stationary hydraulic lash adjusters. Push down on the rocker end at the stationary hydraulic lash adjusters to test for soft or spongy. If soft or spongy stationary hydraulic lash adjusters are found, carefully remove the affected head and inspect the oil passage below the head gasket for debris. If debris is found, inspect the camshaft caps for wear or discoloration due to lack of oil. During inspection if wear or discoloration is found then replace the cylinder head assembly with camshafts. If there is no wear or discoloration, clean the oil passages and replace the head gasket. Technician will use chassis ears or a stethoscope; listen to the right and left side of the engine. Once the noise is isolated or if unable to isolate, remove the piston and rod assemblies from the affected bank(s) to inspect for either; a loose rod bushing in the rod, or a loose wrist pin in the bushing. If this is found, replacing the piston an