Knocks at Idle Hot

^ A/C compressor or generator bearing. Replace as necessary.
^ Valve train. Replace parts as necessary.
^ Improper oil viscosity. Replace with the proper oil for expected temperature.
^ Connecting rod alignment. Replace the connecting rods as necessary.
^ Excessive piston pin clearance.
^ Loose crankshaft balancer. Torque and/or replace.
^ Piston pin offset to wrong side. Install correct piston.
^ Dirt of foreign material lodged in the balance shaft gear or the camshaft gear.