Noise in 340...help

Knocks are not good. If you hold a long screw driver, or extension down on the motor, then touching right up behind your ear, pressed to you,, you can usually tell how deep the sound is. If you move it around on the motor, you can tell where it is coming from. If you hear/feel a nice smooth "whur", that is good, it is a bearing whur.

If it is really a knock, and not clatter, you need to take it apart.

I usually drain the oil, look for metal flake, the bigger the flake, the worse it is.

But each time it is knocking, it is doing more damage.