* Rod knock: This is a noise caused by the connecting rod hitting the crankshaft as it moves up and down. It is usually heard when the engine is under load and can be caused by a variety of factors, including worn rod bearings, a bent connecting rod, or a damaged crankshaft.
* Valvetrain noise: This is a noise caused by the valves hitting the cylinder head as they open and close. It is usually heard when the engine is idling and can be caused by a variety of factors, including worn valve guides, a damaged camshaft, or a loose timing chain or belt.
* Fuel injection noise: This is a noise caused by the fuel injectors as they spray fuel into the cylinders. It is usually heard when the engine is idling and can be caused by a variety of factors, including a dirty fuel injector, a faulty fuel pressure regulator, or a leak in the fuel system.
* Exhaust leak: This is a noise caused by the exhaust gases leaking from the exhaust system. It is usually heard when the engine is idling and can be caused by a variety of factors, including a loose exhaust manifold, a damaged gasket, or a hole in the exhaust pipe.
