1. Valvetrain noise: This can be caused by worn or loose components in the valvetrain, such as lifters, rocker arms, or camshafts. It is typically a high-pitched tapping noise that increases with engine speed.
2. Piston slap: This is a knocking or tapping noise that occurs when the pistons are loose in their cylinders. It is typically a deep, hollow sound that is most noticeable at low engine speeds.
3. Rod knock: This is a knocking noise that is caused by worn or damaged connecting rod bearings. It is typically a loud, metallic sound that is most noticeable at low engine speeds.
4. Main bearing noise: This is a knocking noise that is caused by worn or damaged main bearings. It is typically a deep, rumbling sound that is most noticeable at low engine speeds.
5. Fuel injector noise: This is a ticking or clicking noise that is caused by the fuel injectors opening and closing. It is typically a high-pitched noise that is most noticeable at idle.
If you are not sure what is causing the tapping noise in your BMW 318i e36 engine, it is best to have it inspected by a qualified mechanic.
