1GM water alarm

[Chris]

I have an 82 H27 with a raw water cooled 1GM Yanmar. After about 15 minutes the temp alarm goes off. When I restart a bit later she runs for about 15 minutes and the temp alarm goes off again. I am suspecting that the thermostat is jammed up with salt and not opening when operating temp is reached, but thought I would post for your thoughts before I start wrenching. Suggestions? Thanks, Chris

 

[nick8481]

Raw water Impeller

Did you check the raw water pump impeller,the same thing was happening to me until I checked the impeller in the pump which was all shot to hell. nick

 

[chris]

was water still discharging in exhaust?

NickWas water still discharging in your exhaust? Water still sputtering out my exhaust is what led me to believe it might be the thermostat. After your post I think i may need to check the impeller as wellChris

 

[nick8481]

Yes

Yes water was stil coming out and I thought the same thing and took apart the thermostat also first.The pump was very easy to take apart and replace the impeller for me. nick

 

[Steve Dion]

Yes, But have you check the elbow?

Chris:Do you have a raw water cooled or fresh water cooled version of the motor? The fresh water version has an expansion tank (like an auto).It would be prudent to check/replace the thermostat. I would also suggest that you check the mixing elbow. This is a very common cause of overheating.

 

[Chris]

Water alarm resolved

Thanks everyone for your responses. I replaced the thermostat and impeller today as well as checking the mixing elbow. (The thermostat was frozen closed, the impeller was jambed up in salt incrustation, but the mixing elbow looked clean!) The problem seems to be resolved now. Nick you were right I replaced everything and the zinc in about an hour. Thanks again, Chris