1993 Mercruiser 3.0L Knocking

[Jwally]

My 1993 Mercruiser 3.0L is running really well, but the motor has developed a knocking noise. Oil pressure stays constant at 20-30 psi on the gauge depending on throttle, and I haven't noticed any loss of power. The noise speeds up and is correlated to the amount of throttle applied. Sounds like it's coming from the bottom of the engine, near the crankshaft. I just replaced the harmonic balancer because it had run out. Next time I get to the boat I'll do a compression test and pull the plugs one-by-one to see if the noise changes. Do you more experienced ears have a good idea of what this is? Link to the video is below. Thanks!

https://youtu.be/X-OXukaqj6Q

 

[Alumarine]

Was the knocking there before you replaced the harmonic balancer?

 

[Red955i]

Adjust your belt its hard to hear any noise with that flapping. Does not sound like a rod though. Not heavy enough. After belt is adjusted get a piece of pipe put your ear in one end and move around block. You'll find where noise is