QSB Mystery Noise

[roborr24]

Just finished a wave of spring maintenance on my QSB 5.9 380’s.

After running her home from the boatyard this week I noticed a clicking/knocking noise while at the dock. I cannot isolate where it is coming from exactly other than it is on the front of the engines somewhere near the belts/alternator/fuel pump/water pump.

I recently replaced the water pumps with SMX pumps, and I originally thought it was coming from the tensioner for the water pump V-belt because it has some play in it. I took that belt off and had someone fire the engine so I could determine if it was coming from that or the water pump system. Noise still there.

I took a video that clearly depicts the sound. Wasn’t able to upload the video here, so I put it on youtube and attached the link. You can hear the clanking above the engine noise. https://youtu.be/0khGHfBvguw

I appreciate feedback from anyone who has experienced this noise/issue. Serpentine belt tensioner? Alternator? Fuel Pump? Something in the drive?

Thanks,

Rob

1 user thanked author for this post.

Hans Erik Lie

Topic

[raymond gonzalez]

can you post some pics of the part you changed so we know what it looks like thks

[Hans Erik Lie]

Hi Rob!

Thanks for sharing this experience. I have the same noise on my 425 hp now, at 2200 running hrs. Did you replace complete unit, or bearing in tensioner?
Thanks
Hans

[roborr24]

Just to report back on this. Changed the tensioner and that was the problem. New tensioner, no noise.

Thanks for the input.

1 user thanked author for this post.

Rob Schepis

[Fireisland1]

Did you take off both belts?

[Rob Schepis]

Alternator or fan hub bearing?
Time for the giant screwdriver on the ear trick: https://www.youtube.com/watch?v=U927cYhQXB4

1 user thanked author for this post.

Debbie Apo

[Mike Mason]

Almost sounds like belt chirp but I’ll let the pros chime in.

[Author]

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