Yammer 3YM30

[Bob_Ranft]

Got a Yanmar 3YM30 with just under 90 hours on the clock. Starts well, basically instantaneous, even in depth of winter, tick over is smooth, but vibration above 1200 rpm until say 1900 rpm. Above 1900 rpm engine runs smooth all the way up to 3600 rpm under load. Vibration is worse when throttling back, sometimes sounds like engine is on two cylinders.

Had cylinder head off, checked for flatness, pressure tested, injectors checked, valves lapped in etc. Problem still the same. Next step I think is to look at the fuel pump, or fuel pump timing.

Anyone out there with a Yanmar 3YM30 with similar vibration, or one that runs smooth between 1200 and 1900 rpm.

Thanks in advance.

Bob

 

[PaulRainbow]

Bob, are we talking about vibration when under way, in gear ? If so, could be the drive train ?

 

[Bob_Ranft]

Same in gear or out of gear. Engine is in a cat hooked up to a Sillette outdrive.

 

[jwilson]

My Yanmar 3YM30 is normally quite smooth throughout rev range.

 

[RichardS]

My Yanmar 3YM30 is normally quite smooth throughout rev range.

My two 3YM30s are both pretty smooth at anything other than idle. However, "smooth" is a relative term and, compared to car engines, neither of them are smooth.

Removing cylinder heads and grinding in valves etc on a virtually brand new engine is certainly a rather radical step this early in the fault finding process.

Richard

 

[Bob_Ranft]

It was suspected that the engine may have over heated, hence cylinder head check out. But result still the same.

 

[Scillypete]

I have the 3YM30 also in a catamaran linked to a sillette leg drive, fitted 14 years ago so done quite a few hours, can't say there are any real issues with vibration and certainly not in that range of revs. Being in a boat the slower the revs the more it seems to move but once the revs increase the more stable it gets.

not much help I'm afraid.

 

[coopec]

Bob

Maybe you are not Robinson Crusoe?

https://www.google.com.au/search?so...sy-ab..2.11.3304.6..0j35i39k1.249.zc8XbGkBkEI

Clive

 

[Bob_Ranft]

Fingers crossed, vibration much reduced after 20 minutes run. Have looked at some videos (thanks Clive) vibration no worse than a few others.

Back in water in a couple of weeks, will post an update.

Thanks

Bob

 

[sarabande]

Same engine with vibration in similar rev range. Traced to a loose piece of planking in a stern locker sympathetically doing the heebie-jeebies. The suggestion of drive train above could be extended to framework and other bits in vicinity.