2010 R25 Ranger Tug Yanmar vibration issue

[AlanSutton]

Last season we had a vibration at low RPM or idle. Increasing the RPMs smoothed things out. It seemed like a packing or propeller shaft alignment issue, to me.

I asked Winter Harbor Marina to look at it in the off season and they said it could be motor mounts. They wouldn't know until spring when our boat is launched. It seems like a bit of an overreaction, so I thought I would put the question out on Tugnuts to see if anyone has any thoughts.

What maintenance do the engine mounts require? Can they wear out? I don't know the engine hours because the log is on the boat, but somewhere between 1000 and 1500 hours, I think.
Engine mounts would be an expensive endeavor, which I would hate to get into if I don't have to.

Thanks in advance for any thoughts.
Alan Sutton

 

[NorthernFocus]

It's odd that they would say motor mounts right off the bat. Maybe due to the symptoms that you described. But damaged wheel, alignment, or a worn cutless bearing are typically the first things to check for vibration issues. The most typical problem with mounts is for them to work loose either at the engine mounting bolts or where the mounts bolt to the hull stringers. That would be the most likely issue with the mounts and can be easily checked.

 

[Diver]

Take a good look at your engine mounts. I have the same 2010 RT25. I ended up replacing mine for vibration. The rubber does stiffen with age and can seperate from the mount. Also look at the base plates for corrosion. Mine were paper thin! You can get the mounts without the adjustment shaft from Metalastic Cushyfloat Mounts for a lot less than Yanmar.

 

[BB marine]

I cringe when I hear a repair center say we will not know what is wrong until we launch the boat.

With the boat out of the water there are a number of checks that can be taken. Vibrations can be caused from a number of different issues.

*propeller imbalance (nicks in blades, bent blades, prop erosion). ( Inspection out of the water )
*shaft runout out of spec ( bent shaft ) ( inspection out of the water)
* worn cutlass bearing ( excessive shaft deflection ) (inspection out of the water)
* engine mount ( broken, loose, marine age) (inspection out of the water or in the water)
* injector ( leaking causing a misfire). (Inspection out of the water or in the water)
* damper plate ( worn or broken ) (Inspection out of water or in the water)
* engine to shaft misalignment (inspection in the water)

Given you description of the issue ( Low speed vibration, idle, I would first lean toward motor mount, damper plate, injector issue causing a misfire. That said I would do full inspections of the full drive train. Nothing should be over looked. A full inspection by a diesel mechanic would not hurt. I was at Winter harbor last summer. They have good marine technicians that know marine repair. I think they are weak when it comes to diesel engine service. Ask if they have a certified diesel mechanic before committing to them to look at engine issues. (My opinion)

 

[AlanSutton]

Thanks for the replies.
I talked with Winter Harbor a couple of days ago and they have checked the prop and shaft and cutlass bearing. They said everything is fine except for wear on the cutlass bearing. So I am having them replace it. I'll make sure they inspect motor mounts before launch and then we can see how it goes in the water.
Thanks again,
Alan