Engine vibration when idle and in gear

[Awie Fourie]

Dear Friends,

I have the Hatteras 41 C with 2 x Cummins 450hp Diamond series with Twindisc gearbox transmission. 

Drive shafts new and balanced, shaft alignments good. New cutless bearings, new bullflex coupling rubbers.

When Port engine at idle low rpm notice high vibration at idle, increase rpm slightly vibration disappears.   

When  Port engine in gear forward or reverse low rpm high vibration shaking, soon when rpm increase above 800 – 900 rpm all vibration disappears. When speed up from 2knots till 22knots with 2200 rpm no vibration.

Inspect visual all engine mountings all look ok 

Starboard engine seems fine no vibration.

Any Root Causes for these vibration on Port engine?

 

Topic

[Awie Fourie]

Tony, thank you will first start to confirm true RPM with strobe light.

P & SB engine RPM currently the same at idle.

Only P engine vibrates in idle and when in gear.

SB engine no problem.

I am not sure the connection between Cummins engine and Twindisc gearbox configuration?

Damper plate?

Springs?

Rubber?

 

 

[Tony Athens]

Have you strobed the engines to confirm true RPM at IDLE to 1000 in neutral.   That is where you need to start.

 

 

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Awie Fourie

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