engine problem

[WilliamVaughan]

Regarding the clanking sound. Something that can cause a clanking sound with an engine that is badly miss-tuned is the generator pulley sheaves, when the pulley nut is not tight. The engine stumbles and quickly goes up and down in RPM but the fan, like a flywheel, does not go up and down in RPM. As a result the inner diameter of the pulley sheaves hammer against the generator hub. It makes a loud metallic sound.