An engine knock can be a serious problem and can lead to serious internal engine damage if not addressed quickly and accurately. Here are some possible causes to help you troubleshoot an engine knock yourself. Unfortunately, the chances are that the engine knock IS something serious and could result in some serious labor to fix (or it might be better just to replace the engine).
- The magneto may not be timed correctly.
- The carburetor is set too lean.
- The engine has overheated
- There is carbon build-up in the combustion chamber of the engine.
- The flywheel may be loose.
- The connecting rod is either loose or worn (or both).
- The cylinder is worn and needs service.