Today, on the Gulf for a very good sail, the wind died and after running the engine for a short time the temp gage went to over 220+ degrees. Normal temp for the engine is 100-110 degrees. The boat is a 1980 with a yanmar 15 in it. There is an algae bloom and the slime plugged up the raw water screen that was installed this year. (I may rethink this filter.) After removing the screen, and restarting the engine, there seemed to be no water comming through the engine so it was shut down. The wind having returned I sailed into Clearwater Pass. There after restarting the engine, at last water was exiting the exhaust. However, the temp gauge again climed to 160+ degrees before I shut it down. I hobbled into the slip mostly under sail. The queston is why isn't the engine cooling down if water is exiting the exhaust?
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B
Bill
Manual
Does the manual give a typical operationg temp., 110 seem low to start with, just wondering. Mine operates at 140 to 180. Maybe not as much water is getting through as before if it ran dry, try changing the impeler.
Does the manual give a typical operationg temp., 110 seem low to start with, just wondering. Mine operates at 140 to 180. Maybe not as much water is getting through as before if it ran dry, try changing the impeler.
T
Tom
160 to 170 degrees is normal, but
But if your gage has always shown 110, I would be concerned with the increase in temp. Your gage may not be all that accurate if all it ever showed was 100 to 110, an engine that runs at that is always running cold, very unlikely.
But if your gage has always shown 110, I would be concerned with the increase in temp. Your gage may not be all that accurate if all it ever showed was 100 to 110, an engine that runs at that is always running cold, very unlikely.
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Rob
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Peter
Had the same problem
Check the exhaust elbow. I own an older Hunter 27 with the same Yanmar. Had a bunch of cooling problems until I found someone who found the old elbow to be loaded with rust. Once replaced it ran like a new engine. Good luck.
Check the exhaust elbow. I own an older Hunter 27 with the same Yanmar. Had a bunch of cooling problems until I found someone who found the old elbow to be loaded with rust. Once replaced it ran like a new engine. Good luck.
Think Paul is correct about temp.
Tom: I think that Paul may be correct about the operating temp. This sounds a little cool but not too much. The raw water cooled engines typically do not generate enough heat to even bother using a heat exchanger on the hot water heaters. I would check the raw water impeller and then take a hose to back flush the intake hose back thru the thru hull fitting. We once sucked up some gravel from getting stuck our harbor entrance at low tide. There was some small rocks lodged in the intake at the narrow end of the barbed fitting on the thru hull.
Tom: I think that Paul may be correct about the operating temp. This sounds a little cool but not too much. The raw water cooled engines typically do not generate enough heat to even bother using a heat exchanger on the hot water heaters. I would check the raw water impeller and then take a hose to back flush the intake hose back thru the thru hull fitting. We once sucked up some gravel from getting stuck our harbor entrance at low tide. There was some small rocks lodged in the intake at the narrow end of the barbed fitting on the thru hull.
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Paul F
Progress report
Thanks, everyone. One water pump impeler arm was broken and another only half there. A knowledgeable guy at Boat US said to take a presure hose and flush through the engine. This is a QM15 and there seems to be a tee which directs the raw water to the manifold and to the engine with the maniforld getting the most direct water flow. The presure hose put a very good flow of water at least thru the manifold. I am not as sure about the engine. The next step is to block the flow thru the manifold and see if the engine is as clear. I can not find a thermostat. Does anyone know if there is one on this engine? I would like to at least test it if there is one.
Thanks, everyone. One water pump impeler arm was broken and another only half there. A knowledgeable guy at Boat US said to take a presure hose and flush through the engine. This is a QM15 and there seems to be a tee which directs the raw water to the manifold and to the engine with the maniforld getting the most direct water flow. The presure hose put a very good flow of water at least thru the manifold. I am not as sure about the engine. The next step is to block the flow thru the manifold and see if the engine is as clear. I can not find a thermostat. Does anyone know if there is one on this engine? I would like to at least test it if there is one.
J
james rohr
thermostat location 2qm15
thermostat is located on the top of the exhauste manifold. also if roy are having overheating problems remove the cover, housing the temp sensor,on the rear of the head and check for blockage between the head and block. the rear water passage has a bad habit of rust building up and closing off this passage hence making the no 2 cly run hot. a stiff bent wire or screw driver can be used to clear it without removing the head. i would also seriously consider removing the exhauste manifold and boiling it out with radiator cleaner. if this piece is ruined it can't be replaced, its not available from yanmar any longer. you might also want to consider converting engine to fresh water cooling. i had to replace my engine on my "79" O'day 30 because of internal rusting. rust particals also tend to build up around the cly sleeves. unfortunately theres no way to clean this area out without tearing down the engine. if your 2qm gives up the ghost then it $6500+ to replace it with a new engine. assuming you r@r your self. capn jim sv Que Pasa?
thermostat is located on the top of the exhauste manifold. also if roy are having overheating problems remove the cover, housing the temp sensor,on the rear of the head and check for blockage between the head and block. the rear water passage has a bad habit of rust building up and closing off this passage hence making the no 2 cly run hot. a stiff bent wire or screw driver can be used to clear it without removing the head. i would also seriously consider removing the exhauste manifold and boiling it out with radiator cleaner. if this piece is ruined it can't be replaced, its not available from yanmar any longer. you might also want to consider converting engine to fresh water cooling. i had to replace my engine on my "79" O'day 30 because of internal rusting. rust particals also tend to build up around the cly sleeves. unfortunately theres no way to clean this area out without tearing down the engine. if your 2qm gives up the ghost then it $6500+ to replace it with a new engine. assuming you r@r your self. capn jim sv Que Pasa?
J
John Tesoriero
I agree
According to the 2QM15 Yanmar manual, the normal engine operating temp. for the raw water cooled engine is ~125 degrees, and the overheat alarm goes off @ +140 degrees. The thermostat is located on the top of the exhaust manifold under the cover where the two hoses (one from block & one to mixing elbow) meet. For peace of mind, I change my thermostat every year. Yanmar has special non-strech bolts for the thermostat housing since there is a trendency to overtighten them. I hope you found the missing pice of the impeller blade, since it can block the cooling passages. It is a good idea to back flush the system from time to time and to open each of the drain cocks (one on each side of block & one under exhaust manifold) to check for flow and to detect sand. mud, etc. in the system. If you have not done it in a while, the mixing elbow should be replaced as regular maintenance. Happy Sailing!
According to the 2QM15 Yanmar manual, the normal engine operating temp. for the raw water cooled engine is ~125 degrees, and the overheat alarm goes off @ +140 degrees. The thermostat is located on the top of the exhaust manifold under the cover where the two hoses (one from block & one to mixing elbow) meet. For peace of mind, I change my thermostat every year. Yanmar has special non-strech bolts for the thermostat housing since there is a trendency to overtighten them. I hope you found the missing pice of the impeller blade, since it can block the cooling passages. It is a good idea to back flush the system from time to time and to open each of the drain cocks (one on each side of block & one under exhaust manifold) to check for flow and to detect sand. mud, etc. in the system. If you have not done it in a while, the mixing elbow should be replaced as regular maintenance. Happy Sailing!
P
Paul F
Progress report follow up
Found the thermostat, thanks guys. Also, found why it is good to have a raw water screen. The thermostat had plasic ribbon wound around it. The engine was flushed with the dock fresh water hose, the impeler changed and all engine accesses checked where possible. I left the thermostat out and started the engine. It has returned, to the "normal" 100 - 110 degrees. I am testing the thermostat tonight and will use it if it opens around 125 degrees, if not a new one will be installed. Everything seems back on track. Thanks everyone for your advice. Just a note, last year i installed a fresh water flush to use after running the engine in salt water. It is a simple hose from the sink drain in the head to the engine water pump. It seems to work well and keeps the engine cleaner. It also facilitates a vinegar flush for added cleaning, I nomally do this twice a year. And will likely do it now. I put the vinegar in when going out for a sail just before shutting down the engine. It sloshes around while sailing and is pumped out when motoring back to the slip.
Found the thermostat, thanks guys. Also, found why it is good to have a raw water screen. The thermostat had plasic ribbon wound around it. The engine was flushed with the dock fresh water hose, the impeler changed and all engine accesses checked where possible. I left the thermostat out and started the engine. It has returned, to the "normal" 100 - 110 degrees. I am testing the thermostat tonight and will use it if it opens around 125 degrees, if not a new one will be installed. Everything seems back on track. Thanks everyone for your advice. Just a note, last year i installed a fresh water flush to use after running the engine in salt water. It is a simple hose from the sink drain in the head to the engine water pump. It seems to work well and keeps the engine cleaner. It also facilitates a vinegar flush for added cleaning, I nomally do this twice a year. And will likely do it now. I put the vinegar in when going out for a sail just before shutting down the engine. It sloshes around while sailing and is pumped out when motoring back to the slip.
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