Volvo D4 harmonic?

[GusC@AK]

Hey all.
Recently my port side Volvo D4-260 (V-drive w/ reverse gear) has developed a harmonic resonance or tone. Best described as a low, constant tone at low-mid RPMs (900-1600 rpm). Not a squeaky belt, but very difficult to pinpoint the location. Any thoughts or obvious troubleshooting tips I may have overlooked?

 

[Plum]

Hey all.
Recently my port side Volvo D4-260 (V-drive w/ reverse gear) has developed a harmonic resonance or tone. Best described as a low, constant tone at low-mid RPMs (900-1600 rpm). Not a squeaky belt, but very difficult to pinpoint the location. Any thoughts or obvious troubleshooting tips I may have overlooked?

Do you get the sound from the port engine when the starboard one is not running? Can you post a recording of the sound?

 

[GusC@AK]

Do you get the sound from the port engine when the starboard one is not running? Can you post a recording of the sound?

Not sure if it will pick up on camera, but will try. Yes, it will make the sound when starboard is not running.

 

[GusC@AK]

I confirmed that the sound is lessened when starboard motor is not running, but does not disappear entirely. Also, the sound did not pick up on my iPhone camera/mic. Thoughts?

 

[GusC@AK]

Do you get the sound from the port engine when the starboard one is not running? Can you post a recording of the sound?

Thanks for the response! Please see below for reply regarding starboard engine.

 

[roa312]

We recently experienced an unusual noise from one of our engines (D6 w. outdrives), accompanied by a loss of approximately 300 RPM and a corresponding drop in speed. This was due to fouling, which was unusually severe. It's unclear why the noise was only coming from one engine. I’m not sure if this information is relevant to you, but I thought it might be worth mentioning.