The purpose of bearings is to maintain the proper motion of the crankshaft and pistons. If the bearings are damaged, the noise will probably be produced. It's a good idea to inspect the bearings and replace them if necessary when you experience rod knock. The most frequent reason for engine banging is damaged rods. It will be simpler to fix the troublesome parts and stop the engine banging if you can identify the damaged connection rods. Connecting rod replacement is less expensive than engine replacement.