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Yanmar 3GM30F noise......


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#1 lateral

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Posted 04 January 2020 - 05:09 PM

 Motor has started making tinny, hi-freq  rattly noise intermittently above 2500rpm. 

 Used for bare minimum rest of trip at GB at 2200 with no recurrence.

 I'm thinking:

* take off all belts and check water pumps, alternator bearings.

* Rocker cover and valve clearances

* try and get a repeat and use stethoscope

* in gear out of gear

* Change oil and filter as precaution anyway.(Not due)

 

Any other simple test?

 


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#2 alibaba

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Posted 04 January 2020 - 06:44 PM

1. Does the noise come in at 2500, and then disappear again with increasing revs? I've got the same noise from your description, comes in at 2000, disappears at 2200. Therefore no worry really.
2. Are you sure that it's an engine noise, and not a harmonic from some other structural component? I had that on my last Yanmar, and it turned out to be a slightly loose panel.
Cheers
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#3 harrytom

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Posted 04 January 2020 - 08:12 PM

had that before and simple matter,it a transfer from prop to engine,bit of growth once cleaned noise stopped


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#4 wheels

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Posted 05 January 2020 - 04:15 AM

Lateral, I think you have covered the things to try. Although I wouldn't bother with Valves unless it is due for that kind of maintenance.
Also has stated, it could be from the prop.


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#5 harrytom

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Posted 05 January 2020 - 05:10 AM

One another thing to check is worn or loose zinc on shaft. Have you checked engine mounts?


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#6 lateral

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Posted 05 January 2020 - 07:28 AM

1. Does the noise come in at 2500, and then disappear again with increasing revs? I've got the same noise from your description, comes in at 2000, disappears at 2200. Therefore no worry really.
2. Are you sure that it's an engine noise, and not a harmonic from some other structural component? I had that on my last Yanmar, and it turned out to be a slightly loose panel.
Cheers

1.Haven't tried as when I heard it we were motorsailing (10° heal) decreased revvs and it diminished to nothing. Shut down

and only used at 2200 since.  (twice very short runs)

2. The harmonic from prop shaft is low frequency about 1200rpm and I just go thru it quickly.

This is more a "pingy rattly " noise like a loose plate.

Thanks A.

 

HarryTom

Props clean, but will check again. Also maybe do and engine alignment check.

We've had some rough passages of late.

 

Wheels

Hi wheels, Don't fancy checking clearances today, so I'll leave that until I've nothing left to check!

I'm curious aboat where you are supposed to fill oil to though as are the dipstick marks right for

the angle the yanmar is setup?

 

Thanks guys..... all the best for NY!!!


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#7 lateral

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Posted 12 January 2020 - 08:30 AM

Thanks Ali, my thinking at the dock is its the ss washers packing the shift lever pin rattling at certain rpm.

As I can't find any other reason.


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