I have a leak somewhere in the freshwater cooling circuit of my Universal diesel. It takes a couple of hours for the freshwater coolant to go from full to empty when the engine is running. The rate at which I lose coolant seems to be increasing over the past months. I'm looking for any and all suggestions for tracking down this leak. As far as I can figure, the possabilities are: 1) Leaking hose or fitting. I haven't found water anyplace (including the bilge) so I suspect its not this. 2) Leak in domestic hot water heat exchanger. More than a gallon of coolant disappears in an hour or two during which time we use no tap domestic hot water, so I suspect this isn't the case. 3) Leak in engine exhaust heat exchanger. I think this is the most likely culprit. 4) Leak in engine, internally. The oil is fine so there is no leakage into the crankcase. Engine starts and runs very smoothly with no smoke, so I don't think it's leaking into a cylinder. 5) Leak in engine externally. This is possible as the coolant would probably evaporate as fast as it leaks out so I wouldn't find water pooled anyplace. SO....am I missing a potential leak? How can I track this down? Can I test the engine heat exchanger without pulling it off the engine? I haven't found water anyplace (including bilge) so I suspect it isn't (1). More than a gallon of coolant disappears in a an hour or two during which time we use no domestic water, so I suspect it's not (2)
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Check the cap and pressure test the system.
You use the same pressure tester utilized for automobile cooling systems. They have an adapter to test the cap; pressurize to 13 PSI and if it fails to hold at least 11 PSI after 30 seconds replace the cap. Now pressurize the system to 15 PSI and if the pressure does not hold constant for at least two minutes check for a leak. As the test is performed with the engine cold even small leaks will not evaporate and leave a trail. Listen for a hissing or bubbling sound. If no leaks are found, disconnect the sea water outlet hose from the heat exchanger. Again repressurize the system and if water continues to flow from the heat exchanger outlet it is a leak within the exchanger itself. If no leaks are found then there is probably an internal leak because of a blown head gasket, cracked block or cylinder head. Coolant drawn into the combustion chamber will usually be blown out the engine as water vapor with the exaust. Check for white smoke. You can get a pressure tester from your automotive supply store or you can rent one from a tool rental place. Without pressure testing small coolant leaks are very hard to find. Good luck.
You use the same pressure tester utilized for automobile cooling systems. They have an adapter to test the cap; pressurize to 13 PSI and if it fails to hold at least 11 PSI after 30 seconds replace the cap. Now pressurize the system to 15 PSI and if the pressure does not hold constant for at least two minutes check for a leak. As the test is performed with the engine cold even small leaks will not evaporate and leave a trail. Listen for a hissing or bubbling sound. If no leaks are found, disconnect the sea water outlet hose from the heat exchanger. Again repressurize the system and if water continues to flow from the heat exchanger outlet it is a leak within the exchanger itself. If no leaks are found then there is probably an internal leak because of a blown head gasket, cracked block or cylinder head. Coolant drawn into the combustion chamber will usually be blown out the engine as water vapor with the exaust. Check for white smoke. You can get a pressure tester from your automotive supply store or you can rent one from a tool rental place. Without pressure testing small coolant leaks are very hard to find. Good luck.
Pressure test
I too had a similar problem on my W21. The ONLY way i found the leak was with a pressure test. I found a matco kit on Ebay for cheap.
I too had a similar problem on my W21. The ONLY way i found the leak was with a pressure test. I found a matco kit on Ebay for cheap.
burnt anty
Totally agree with the others. If it was a leak into the cylinder or exhaust manifold you would know as antifreeze turns to white fog that does not dissapate. Just totaly engulfs your boat. Much more likely a heat exchanger leak and it is getting mixed with the raw water then put into the exhaust. Good luck
Totally agree with the others. If it was a leak into the cylinder or exhaust manifold you would know as antifreeze turns to white fog that does not dissapate. Just totaly engulfs your boat. Much more likely a heat exchanger leak and it is getting mixed with the raw water then put into the exhaust. Good luck
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