We were out in San Diego bay this weekend and needed to use the Yanmar 27hp fresh water cooled engine for quite awhile (probably an hour), due to weather conditions. We check all fluid levels before every sail and did not notice any issues before we left the dock this weekend. When we were returning to the marina, we were conducting an exercie to determine the prop direction on the boat which involved running in forward at 2500 rpm, then very quickly going to reverse power, this seemed to tax the engine (based on the increased vibration and noise). Shortly thereafter the engine overheat sensor (audible alarm) went off. We returned to the slip immediately (within 10 minutes) and let her cool off for awhile. Later recheked the oil/overflow etc no problems. I suspect that we just overworked the engine- has anyone else had this happen? Also, once you get a warning indicator, is it similar to a car in that the thremostat needs to be replaced? I wish there was an actual temperature gague on the boat! It is a 1999 34'. Thanks.
Engine temperature warning indicator
- Thread starter Sol Perros
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It's almost a wild guess to suggest the cause without knowing lots more about the engine type, hours, maintenance record, etc.
It could be as simple as a dirty prop, dirty bottom, bad thermostat or clogged raw water strainer or as insidious as a clogged exhaust elbow, clogged heat exchanger, bad water pump, etc.
The more detail you can provide, the more issues can be ruled out.
It could be as simple as a dirty prop, dirty bottom, bad thermostat or clogged raw water strainer or as insidious as a clogged exhaust elbow, clogged heat exchanger, bad water pump, etc.
The more detail you can provide, the more issues can be ruled out.
Thanks Don,
Well there are 320 hours on the (original) engine. Maintenance log is complete and comprehensive, there was water circulating (sea water cooling the exchanger). As it happened after aggressive use I suspect we over-taxed the engine. When run later in the day all systems seemed normal. Just wondered if this was usual...thx. Also does the thermostae usually need replacing after something like this?
Well there are 320 hours on the (original) engine. Maintenance log is complete and comprehensive, there was water circulating (sea water cooling the exchanger). As it happened after aggressive use I suspect we over-taxed the engine. When run later in the day all systems seemed normal. Just wondered if this was usual...thx. Also does the thermostae usually need replacing after something like this?
Sol, I have the same engine and same hull. IMHO, doing an "emergency stop" should not cause an overheat. So a couple of things to consider...
vibration and noise - did you look to see how much kelp you were dragging before the exercise? That could cause vibration and an already hot engine to overheat.
thermostat - not likely but possible. My engine has over 1000 hours on it. See if anyone around you has a thermal gun. You can warm it up and take its temperature.
alarm - I normally try to get more than one symptom to confirm something. I have caught my motor ABOUT to overheat twice. Kelp in raw water strainer, and a bushel of kelp trailing us wrapped around shaft and rudder (at night). Our engines make steam before the alarm goes off normally. Did ya see any of that. Yes you can smell it too! Your overheat alarm sensor is right next to the thermostat housing Is it connected properly?
Best of luck
vibration and noise - did you look to see how much kelp you were dragging before the exercise? That could cause vibration and an already hot engine to overheat.
thermostat - not likely but possible. My engine has over 1000 hours on it. See if anyone around you has a thermal gun. You can warm it up and take its temperature.
alarm - I normally try to get more than one symptom to confirm something. I have caught my motor ABOUT to overheat twice. Kelp in raw water strainer, and a bushel of kelp trailing us wrapped around shaft and rudder (at night). Our engines make steam before the alarm goes off normally. Did ya see any of that. Yes you can smell it too! Your overheat alarm sensor is right next to the thermostat housing Is it connected properly?
Best of luck
Rick- Good idea about dragging kelp! I will check that. That would explain why it ran fine at idle in the slip later. Checked the sensor- ok there. There was a little steam (not much) before we backed it off and returned to slip. Thanks much!
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