my 3gmf yanmar engine is overheating. just replaced the raw water cooling pump , plenty of flow out of the pipe. my coolant in my manifold is dissapearing, after fifteen minutes of run time. engine starts great and sounds great. my water heater heat exchanger seems ok , no anti freeze in the hot water outlets. then when the coolant is gone i overheat. what is going on. where is the co ollant going? i do not see a film on the water where the raw water pump discharges. ???? i am in fresh water but the boat came from salt water, three years ago. any ideas.
yanmar cooling question
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Unfortunately sounds like a hole in a heat exchanger tube. Blowing coolant into the raw water .. would probably not be noticeable out the exhaust. Could be a bad gasket on one of the ends, but that would be a long shot.. easy to pull the tube bundle and inspect.. Expensive to replace the bundle, but if you have industry in the area, you might be able to find someone to re-tube it locally..
EDIT before you pull the end caps, you can get a mechanic to pressure test the system using a pump and gauge that goes on in place of the "radiator" cap on top of the heat exchanger shell/exhaust manifold..
EDIT before you pull the end caps, you can get a mechanic to pressure test the system using a pump and gauge that goes on in place of the "radiator" cap on top of the heat exchanger shell/exhaust manifold..
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EDIT before you pull the end caps, you can get a mechanic to pressure test the system using a pump and gauge that goes on in place of the "radiator" cap on top of the heat exchanger shell/exhaust manifold..[/quote]
Good idea and you can do it yourself. Just rent one of those automotive pressure tester and have a go at it. Fill the system, then put the tester in place of the cap as Kloudie mentioned, start the engine and watch the tester. Pressure should go up to about 15 psi and be stable there. As engine runs, if pressure decreases you have a leak in the system. I would also do it with the hot water heat exchanger by-passed so you can check the engine, and obviously afterwards the Heat Exchanger. Good luck
Good idea and you can do it yourself. Just rent one of those automotive pressure tester and have a go at it. Fill the system, then put the tester in place of the cap as Kloudie mentioned, start the engine and watch the tester. Pressure should go up to about 15 psi and be stable there. As engine runs, if pressure decreases you have a leak in the system. I would also do it with the hot water heat exchanger by-passed so you can check the engine, and obviously afterwards the Heat Exchanger. Good luck
Good advice from Claude .... plus you can obtain a 'black light' cooling water analysis kit from most sources that cater to auto mechanics.
How this works is --- you put a special dye tablet into the cooling water, run the engine for a specified time, then when the water cools down - open the fill cap and shine 'black light' into it; if with black light showing into the opening if the water is now 'fluorescing' its a positive indication that you have a blown head gasket; and/or, in the case of a marine engine a pin hole water leak in your exhaust manifold. The dye when it absorbs carbon monoxide in the cooling water gives off the 'fluorescence' when viewed under 'black light'.
How this works is --- you put a special dye tablet into the cooling water, run the engine for a specified time, then when the water cools down - open the fill cap and shine 'black light' into it; if with black light showing into the opening if the water is now 'fluorescing' its a positive indication that you have a blown head gasket; and/or, in the case of a marine engine a pin hole water leak in your exhaust manifold. The dye when it absorbs carbon monoxide in the cooling water gives off the 'fluorescence' when viewed under 'black light'.
Yes, pressure test the anti side of the system before proceeding. If she will not hold pressure then there is your problem just need to find where the anti is leaking out
If you are not losing your coolant into your bilge and it is not being lost in your water heater, then there are only two places it can go. It is being lost in the sea water flow or being burnt in the engine. I think the pressure tester will tell that you have a leak, but it won't tell you if the leak is inside the engine (head gasket?) or to the raw water flow. I think if you were to fill the engine cooling system with water and some food coloring or flourescent dye, all you would have to do is look at your exhaust flow to pinpoint the leak.
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