I have a 1983 31 with a Yanmar 2GB and my water temp alarm goes off after about 5 minutes. I have a new water pump (even put a new impeller in it). Checked the belts, it's turning. I now the thermostat is working (even tried it taking it out). Water is coming out the back. Cleaned the strainer. It is a raw water cooled engine (no radiator}. I let it cool down, starts up without the alarm, but a few minutes later, you know that shreik starts again. I just can't figure out why the alarm keeps going off, any suggestions?
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defective sending unit ?
you first need to know if the engine is overheating, you might want to get a temperature gun and check the actual water engine temp or install a water temp gauge. If it is not overheating try a new sending unit to the gauge. Also check to see that there is no air lock or some other blockage of the engine cooling system. Is the exhaust water cold or warm? cold could indicate that the water is bypassing the engine block and not cooling the engine Warm would indicate that the block is being cooled. First things first and find out if the engine is realy overheating or just a bad alarm, Hope this helps!
you first need to know if the engine is overheating, you might want to get a temperature gun and check the actual water engine temp or install a water temp gauge. If it is not overheating try a new sending unit to the gauge. Also check to see that there is no air lock or some other blockage of the engine cooling system. Is the exhaust water cold or warm? cold could indicate that the water is bypassing the engine block and not cooling the engine Warm would indicate that the block is being cooled. First things first and find out if the engine is realy overheating or just a bad alarm, Hope this helps!
Sounds like the ol' elbow to me.
John: Sound like the good old mixing elbow syndrome to me. This is where the exhaust and your cooling water come together. You may be getting water out the exhaust but maybe it is not enough. If you can remove the exhaust hose where it exits the elbow, sometimes you can use a dental type mirror and a flash light and see if you have a blockage in the elbow. Other wise it may be worth getting a new gasket and removing the elbow to see if it is plugged. When the boats live in salt water they tend to corrode too.
John: Sound like the good old mixing elbow syndrome to me. This is where the exhaust and your cooling water come together. You may be getting water out the exhaust but maybe it is not enough. If you can remove the exhaust hose where it exits the elbow, sometimes you can use a dental type mirror and a flash light and see if you have a blockage in the elbow. Other wise it may be worth getting a new gasket and removing the elbow to see if it is plugged. When the boats live in salt water they tend to corrode too.
Overheating Yanmar Disel
John, There is a good chance that you have an air lock. I doubt if your elbow is plugged but what the heck, check it any how. Quite often its an air lock that prevents the cooling water from doing its thing. Make sure you bleed off the water filter as your engine is running. Usually by releasing the valve on the bottom of the raw water cooling filter any excess air will purge out at this point. As with previous replys make sure your alarm signal is real and not false. Good Luck Barrie
John, There is a good chance that you have an air lock. I doubt if your elbow is plugged but what the heck, check it any how. Quite often its an air lock that prevents the cooling water from doing its thing. Make sure you bleed off the water filter as your engine is running. Usually by releasing the valve on the bottom of the raw water cooling filter any excess air will purge out at this point. As with previous replys make sure your alarm signal is real and not false. Good Luck Barrie
Plugged water intake
Your over-heating problem is likely the elbow or air lock, but try this easy process of elimination first. We have an occasional sea weed problem where we dock. Large strands of sea weed will plug the through-hull, or the hose leading from the through-hull to the strainer. Try this: 1) close the through hull sea cock. 2) disconnect the intake hose from the STRAINER. 3) hold the hose straight up, the disconnected end will most likely be above the water line. 4) slowly open the sea cock. If major water comes out, close it and end here. 5) push a slender rod or coat hanger wire through the hose, far enough to go past the through-hull. Work it to clear any blockage. 6) close the sea-cock and re-connect the hose. I hope your over-heating problem is this easy. Good luck. John 83 H31, hull #63
Your over-heating problem is likely the elbow or air lock, but try this easy process of elimination first. We have an occasional sea weed problem where we dock. Large strands of sea weed will plug the through-hull, or the hose leading from the through-hull to the strainer. Try this: 1) close the through hull sea cock. 2) disconnect the intake hose from the STRAINER. 3) hold the hose straight up, the disconnected end will most likely be above the water line. 4) slowly open the sea cock. If major water comes out, close it and end here. 5) push a slender rod or coat hanger wire through the hose, far enough to go past the through-hull. Work it to clear any blockage. 6) close the sea-cock and re-connect the hose. I hope your over-heating problem is this easy. Good luck. John 83 H31, hull #63
Overheating
Sounds to me like a sending unit, if the alarm goes of within five minutes of start up.
Sounds to me like a sending unit, if the alarm goes of within five minutes of start up.
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