3GM30F won't turn over under load

[Rich]

My Yanmar 3GM30F won't turn over under load. It will turn over with compression released. Batteries are good. Any ideas?

 

[Bob McDowell]

Connections or Starter

Check the connections on the batteries and the starter if these are good and clean then suspect your starter.

 

[Justin Wolfe]

Batteries are good?

Are you sure? We just put four new batteries on our boat in June. Started having problems starting the engine. Turns out one of cells had gone bad after only 3 months. Replaced it under warranty and all is well. We bought a $4 hydrometer and it told the story of the bad cell loud & clear.

 

[Chuck Wolfe]

Connectors

Just went through one of these with my bow neighbor's diesel. Batteries were okay. Three mechanics kept saying it was the starter. Starter was rebuilt and wouldn't turn. We jumped with a cable from the battery to the main terminal and it didn't help. After great aggravation and hours and hours of removing the starter (three times), it turned out to be a connector from the cable going to the main terminal. chuckwolfe@innocent.com

 

[Scott Johnston]

Check for water.

How's your fuel?Could you have water in your tank?Water does not compress and that could be why the starter wont turn the engine over. The clue here was that the engine is turning over with the compression levers released. I may be way off base but it's worth checking.Scott83-H34 Island Hops

 

[Rich]

Thanks to all hands responding

Thanks to all hands who responded to my problem. Scott was right; there was water in the bottom of the tank. System's been cleaned and I'm back underway again.