This Preliminary Information communication provides information to the technician about vehicles that may have a knocking noise from the engine under light load while driving with engine speed between 1100 and 1800 rpm. Technician should use stethoscope or chassis ears and listen for this knock at the intake manifold and at the lower engine. If the noise is more noticeable in the intake manifold, then replace the intake manifold assembly and reevaluate the concern. If the noise is still present then continue with normal Service Information diagnosis for an engine knock concern.
