The engine overheat horn sounds a lot, and the engine does not appear to be hot. The boat is a 30' 1981 Hunter and the engine is a Yanmar 2Q15. The water comes through the petcock o.k., I cleaned the strainer, removed the water pump and the impeller is o.k. Is there some sort of sensor that might be bad, causing the horn to sound when the engine is not really hot? I normally run the engine at 2200 to 2300 rpm, but this week the horn sounded when I was running at only 1800 rpm. Finally, I had a diesel mechanic check it recently, he cleaned the injectors, adusted the valves, etc., but that didn't help the horn sounding problem. I would appreciate any comments or suggestions. King Elliott, "King Louie", Miami, FL BB2F
Engine Overheat Horn
- Thread starter King Elliott
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you didn't mention
what the engine temperature is when the horn sounds. Did you/can you measure it or is there a temp guage?
what the engine temperature is when the horn sounds. Did you/can you measure it or is there a temp guage?
Overheat
I had the same problem...... water was flowing out the stern ......changed the mixing elbow and put on a new hose ............ solved the problem ...... hose --- from Kragen .....radiator hose .......dick
I had the same problem...... water was flowing out the stern ......changed the mixing elbow and put on a new hose ............ solved the problem ...... hose --- from Kragen .....radiator hose .......dick
Check Mixing Elbo &Prop&Impeller
Youneed to check the cooling system sensor,taake it out and clean it,check the elbo might need cleaning,but check the impeller also inportant,is it fresh water colled check the antifreez,raw water cooled check belts and hoses and anything related to the cooling system.
Youneed to check the cooling system sensor,taake it out and clean it,check the elbo might need cleaning,but check the impeller also inportant,is it fresh water colled check the antifreez,raw water cooled check belts and hoses and anything related to the cooling system.
maybe
Had a similar problem on H36 new from factory. It ended up being pure antifreeze - not 1/2 water. As soon as we mixed it, problem went away. Might be something easy to check.
Had a similar problem on H36 new from factory. It ended up being pure antifreeze - not 1/2 water. As soon as we mixed it, problem went away. Might be something easy to check.
Why the importance of 50-50 coolant mix?
Ater overheating I checked everything, m-elbow, thermostadt, cap, heat exchanger, replaced impeller, all looked ok. I then mixed 50-50 and haven't had another problem. After all that I'm not sure what happened, air pocket or straight coolant issue or ??. Yanmar 4jh-te Hunter 45 Dan
Ater overheating I checked everything, m-elbow, thermostadt, cap, heat exchanger, replaced impeller, all looked ok. I then mixed 50-50 and haven't had another problem. After all that I'm not sure what happened, air pocket or straight coolant issue or ??. Yanmar 4jh-te Hunter 45 Dan
Kink in the wiring harness.
You do not mention if the temperature light goes on at the same time. We had our temperature warning light go on and off at random for a while but the buzzer would not sound. It was finally traced to a cut insulation on the electrical wiring harness cables which finally ended up producing a short. Our buzzer is supposed to sound if the engine overheats, the oil pressure drops or the charging system fails. Without the light how do you know the problem is temperature and not a loose conection on the alternator? Hope this gives you more options to look at.
You do not mention if the temperature light goes on at the same time. We had our temperature warning light go on and off at random for a while but the buzzer would not sound. It was finally traced to a cut insulation on the electrical wiring harness cables which finally ended up producing a short. Our buzzer is supposed to sound if the engine overheats, the oil pressure drops or the charging system fails. Without the light how do you know the problem is temperature and not a loose conection on the alternator? Hope this gives you more options to look at.
Check the thru-hull
Had similar problems. Are you getting water out your exhaust? My exhaust is at the water line, so hard to tell. Depending on the through-hull configuration for your sea water, the valve and elbow can catch and get clogged with sea grass.
Had similar problems. Are you getting water out your exhaust? My exhaust is at the water line, so hard to tell. Depending on the through-hull configuration for your sea water, the valve and elbow can catch and get clogged with sea grass.
Other options
I had the 2QM15 on my previous 1980 H30. It sounds like you have checked all of the obvious things and I can only recommend a few additional points. The temperature sensor on that engine has a history of problems, especially sticking closed and I would recommend that you replace it. The sensor is found on the rear of the engine, port side near the aft zinc. The engine is raw water cooled and the thermostat rusts up easily and can stick. The thermostat is found under the oval plate on top of the exhaust maifold where the hose to the exhaust elbow begins. If you have good water flowing through the engine and everything else seems OK then you probably have a restricted mixing elbow. Running that engine at 2200-2300 RPM is too low and will lead to fouling the exhaust system. I found the sweet spot to be about 2800 RPM on my boat. If or when you have the mixing elbow off the engine, you will have access to the rear of the exhaust manifold and can flush any gunk sand or grit out of the cooling jacket around the exhaust manifold.
I had the 2QM15 on my previous 1980 H30. It sounds like you have checked all of the obvious things and I can only recommend a few additional points. The temperature sensor on that engine has a history of problems, especially sticking closed and I would recommend that you replace it. The sensor is found on the rear of the engine, port side near the aft zinc. The engine is raw water cooled and the thermostat rusts up easily and can stick. The thermostat is found under the oval plate on top of the exhaust maifold where the hose to the exhaust elbow begins. If you have good water flowing through the engine and everything else seems OK then you probably have a restricted mixing elbow. Running that engine at 2200-2300 RPM is too low and will lead to fouling the exhaust system. I found the sweet spot to be about 2800 RPM on my boat. If or when you have the mixing elbow off the engine, you will have access to the rear of the exhaust manifold and can flush any gunk sand or grit out of the cooling jacket around the exhaust manifold.
Thanks, John
Thanks, John, your suggestions are helpful. I have already removed the thermostat since the water here is seldom lower than 74 degrees, but I'll look for the sensor. Thanks for replying. King Elliott
Thanks, John, your suggestions are helpful. I have already removed the thermostat since the water here is seldom lower than 74 degrees, but I'll look for the sensor. Thanks for replying. King Elliott
Overheating alarm
I now own the boat John Tesoriero was talking about. I had the exact same problem last year. Removing and cleaning out the mixing elbow solved the problem. I did that after all else failed. You need to re-install the thermrostat, it has nothing to do with the water temp in which you are sailing. It does regulate the water temp of your cooling system within the motor.
I now own the boat John Tesoriero was talking about. I had the exact same problem last year. Removing and cleaning out the mixing elbow solved the problem. I did that after all else failed. You need to re-install the thermrostat, it has nothing to do with the water temp in which you are sailing. It does regulate the water temp of your cooling system within the motor.
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