Rough running M25XPB at low idle

[breton]

New 1999 MKII #620 28’ boat but I am concerned about rough running below 1500 rpms. i will try to get a mechanic either before or after I get the boat hauled. I changed both fuel filters before I launched. I like the way the engine pushes this boat (way faster than my Pearson 28). What do you think?
Thanks.

 

[Tally Ho]

Can you make a little movie to post of the engine idling (show the engine so we can see how much it shakes) and then rev it up until it runs smooth. It may help us understand what you are dealing with.

Greg

 

[john2]

They vibrate a lot at low rpm's. Just don't idle in gear, throttle up untill it runs smooth.
make sure engine mounts are good and the damper plate is oke.

 

[breton]

Thanks. How do I make sure the damper plate is ok?

 

[Project_Mayhem]

My M25XPA was set to a very high idle when I first got it on the hard. Idle was lowered but ran rough. After using the motor for a few weeks it smoothed itself out

Shockingly, there's a TSB that states the engine should idle at 1500. Docking at that RPM would be interesting!

 

[breton]

What’s a TSB and where do I find that?

Thanks

 

[jssailem]

What is a damper plate?

A damper plate is a mechanical component that connects the flywheel of an engine to the input shaft of a gearbox, absorbing vibrations and shocks to protect the gearbox from wear and damage. It functions similarly to a shock absorber, ensuring smooth power transfer in various machinery, especially in marine applications.​

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Here is an example of a damper plate.​

This one is bad. Can you tell why?​

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You really can only know they are bad if you remove the transmission and look.​

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Your suspicions may arise if you hear a lot of rattling at idle and when you try to put the transmission in gear it will not go is very difficult to go into gear.​

 

[jssailem]

TSB = Technical Service Bulletin

 

[Project_Mayhem]

I ran mine at 1500 RPM idle. I wouldnt recommend it. It's hard on the transmission and makes docking difficult. I'm idling around 600RPM. I might bump that up to 800. It died once when I put it in reverse to slow down from a higher than normal speed. Hasn't done it since though