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Joe, Marine Mechanic
Category: Boat
Satisfied Customers: 7251
Experience:  ASE, electronics, Marine mechanical and electronics, pwc, wiring, all around repair tech,
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Starboard engine sounds like it's knocking and not balanced.

Customer Question

Starboard engine sounds like it's knocking and not balanced. Noisier than port engine. How serious is this?
Submitted: 2 years ago.
Category: Boat
Expert:  Joe replied 2 years ago.


Thank you for allowing me to assist you, my name is Joe and I will be happy to assist you with your concern today.

It really depends, what you could simply have is a bad motor mount or shaft coupler, bent driveshaft and or pump issue, with that said you could also have a serious problem internal be it top or bottom end. Pull a compression test and make sure that is ok, next check your motor mounts, one could simply be broken or multiple broken as well as loose exhaust, check driveshaft to be straight, if engine and pump as not aligned you will have a vibration to major noise depending on how bad.

If the problem is engine internal related then you can listen with a stethoscope to try and see where the sound is but a tear down will be required to fully diagnose at that point.

If it is as bad as you make it sound, it is not good and is serious enough to warrant not using it until it gets looked at, even if it is something small, if left unfixed it could lead to major problems.

Thank you!
- Joe

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If you need any further assistance you can reply back at any time for my help.
I'd be happy to answer any other questions you have even if not related.

Customer: replied 2 years ago.
Sorry Joe I didn't say they are Yamaha jet engines (sx 230 high out put) does this change things
Expert:  Joe replied 2 years ago.

Good afternoon,

Sorry for the delay. Dealing with septic issues. My apologies.

Nope, in fact I already figured that by the make and model you provided as it is a jet boat, so what I explained does apply.

Thanks again,