View Full Version : Yanmar 2QM15 overheats

10-24-2008, 05:34 PM
Raw water cooled in salt water and over heats at high RMP's. Intake is clear and exhaust volume looks OK. Maybe a clogged passage. Any sugestions on how to clear?

10-24-2008, 06:22 PM
"Hi Alex, Remove the zinc plug and cap from the front of the cylinder head. Clean out the debris that builds up from the flaking of the zinc. This debris will devert the water flow and allows the sensor to give a high false reading. Replace zincs if need be and new gaskets & copper rings

10-24-2008, 10:30 PM
Check the following:
Fresh water pump.
Raw water pump impeller. Just because you appear to have good exhaust water flow the impellor may have started degrading.
Exhaust elbow.
Clogged heat exchanger.
Thermostat may not be opening fully. Remove it and try without.