Knocks at Idle When Hot

^ Loose or worn drive belts. Adjust tension or replace as necessary.

^ A/C Compressor or generator bearing. Replace as necessary.

^ Valve train. Replace parts as necessary.

^ Improper oil viscosity. Install proper viscosity oil for expected temperature.

^ Excessive piston pin clearance. Ream and install oversize pins. Or replace piston and pin.

^ Connecting rod alignment. Check and replace rods as necessary.

^ Insufficient piston to bore clearance. Hone bore and fit new piston.

^ Loose crankshaft balancer. Torque and/or replace worn parts.

^ Piston pin offset to wrong side. Install correct piston.