Yanmar 3ym30

P

phil horey

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1 May 2014
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I have a Yanmar£ym30 with about 80hrs on the clock. The overheating light has started to come on at first intermitently but now as soon as I fire the engine up with the associated buzzer. Have checked the impeller and the there is plenty of water coming out of the exhaust and it is cool. Also when turning the starter key to the on position the oil pressure light fails to illuminate. Is it a panel fault , wiring or thermostat problem? Any ideas?
Cheers Phil
 
I had a similar problem. I concluded it was an electrical short caused by a seawater leak from the exhaust elbow gasket. I tightened that up, washed off the salt, and the problem went away,
 
I have a 2YM20 with 430hrs never had a problem so far, but this sounds like electrical going by the symptoms you describe. How you solve this not sure but I would start by having a good clean and check around all engine electrical connections.
 
DaveRo said:
I had a similar problem. I concluded it was an electrical short caused by a seawater leak from the exhaust elbow gasket. I tightened that up, washed off the salt, and the problem went away,
Click to expand...

I think you may be on the right lines , Im sure it is an earth problem somewhere , but not sure about the thermostat, but on an engine thats only done 80hrs from new last year?
 
phil horey said:
I have a Yanmar£ym30 with about 80hrs on the clock. The overheating light has started to come on at first intermitently but now as soon as I fire the engine up with the associated buzzer. Have checked the impeller and the there is plenty of water coming out of the exhaust and it is cool. Also when turning the starter key to the on position the oil pressure light fails to illuminate. Is it a panel fault , wiring or thermostat problem? Any ideas?
Cheers Phil
Click to expand...

I and others have had genuine overheating problems with 3YM30s when pushing a largish yacht at high revs. Early engines had a smaller heat exchanger, those who complained got a new larger one fitted under warranty. My understanding is that all recent engines (post 2006ish) have the larger heat exchanger. Nevertheless I suspect these engines are only marginally adequately cooled even with the new heat exchanger. I still occasionally get overheat alarms if the boat is driven hard under power for long.

However, I did also for a time have some random overheat alarms at low revs, and sometime straight after startup, which were obviously false alarms. These were traced to the temp sensor wire rubbing on the block and shorting out. As you say the oil light fails as well the oil pressure switch may be faulty, or the wire may be frayed and shorting.
 
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