My boat is powered by a Yanmar 3GM30F (tag says 24 HP). Its a 1991 that I bought used this past year. Problem is the coolant goes into the overflow tank but does not return back into the engine. The coolant is not leaking into the bilge or appearing in the oil? I have tightened all connections that I could see and replaced the filler cap. I have not noticed any unusual exhaust. Maybe the heat exhanger? Anyone know where I should be looking? Thanks
losing coolant
- Thread starter ron witmer
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Whats the COLOR of your cooling fresh water????
Check for: pin hole in the heat exchanger tubes, leakey shaft seal on the water pump, blown head gasket. 1. Pin hole in the heat exchanger .... get a 'radiator / cooling system test pump' from an auto supply store, attach it to the 'radiator cap connetion' of the heat exchanger, pump it up to 15 psi and let it 'sit'. Come back 1/2 hour later and observe if the gage pressure is the same (system OK) or decreased (leak in the exchanger, blown head gasket, leak in the shaft seal of the water pump, etc. Before you start the test, accurately measure the crankcase oil level on the dipstick .... if that 'oil' level rises - indicates the strong possibility of a blown, leaking shaft seal on the water pump. 2. A blown head gasket - (sometimes will be indicated by dark water color or visible soot in the cooling water). A blown head gasket sometimes will allow the high pressure of combustion to deliver soot into the cooling loop on the power stroke of the piston, and will suck coolant from the cooling side into the combustion chamber on the 'suction' stroke. Such a condition will yield high dissolved carbon dioxide and carbon monoxide in the cooling water. Find a mechanic or automotive machine shop who can do 'black light' testing of the cooling water. Then, go to an automotive supply store (NAPA, etc.) and get the 'indicator chemical', put it into the cooling system and run the engine for several hours under normal operating conditions, then take a sample of the cooling water (in a CLOSED jar, etc.) to the person to do the 'black light' testing. You can also assay for a blown head gasket by removing the injectors (so you can SEE into the cylinders) and pump up the radiator test pump repeatedly .... looking for water in one of the cylinders. Water in one of the cylinders is NOT a good thing for an engine! ... causes the piston rings to 'stick'/rust in their piston grooves which will eventually break the rings. 3. Pin hole in the heat exchanger ............ Empty/drain the raw water side, block/plug both inlet and outlet of the fresh water side, then fill with water, apply pressure to the fresh water side via the radiator cap pump .... watch for the eventual leakage of water from the fresh water side to leak into the raw side. hope this helps.
Check for: pin hole in the heat exchanger tubes, leakey shaft seal on the water pump, blown head gasket. 1. Pin hole in the heat exchanger .... get a 'radiator / cooling system test pump' from an auto supply store, attach it to the 'radiator cap connetion' of the heat exchanger, pump it up to 15 psi and let it 'sit'. Come back 1/2 hour later and observe if the gage pressure is the same (system OK) or decreased (leak in the exchanger, blown head gasket, leak in the shaft seal of the water pump, etc. Before you start the test, accurately measure the crankcase oil level on the dipstick .... if that 'oil' level rises - indicates the strong possibility of a blown, leaking shaft seal on the water pump. 2. A blown head gasket - (sometimes will be indicated by dark water color or visible soot in the cooling water). A blown head gasket sometimes will allow the high pressure of combustion to deliver soot into the cooling loop on the power stroke of the piston, and will suck coolant from the cooling side into the combustion chamber on the 'suction' stroke. Such a condition will yield high dissolved carbon dioxide and carbon monoxide in the cooling water. Find a mechanic or automotive machine shop who can do 'black light' testing of the cooling water. Then, go to an automotive supply store (NAPA, etc.) and get the 'indicator chemical', put it into the cooling system and run the engine for several hours under normal operating conditions, then take a sample of the cooling water (in a CLOSED jar, etc.) to the person to do the 'black light' testing. You can also assay for a blown head gasket by removing the injectors (so you can SEE into the cylinders) and pump up the radiator test pump repeatedly .... looking for water in one of the cylinders. Water in one of the cylinders is NOT a good thing for an engine! ... causes the piston rings to 'stick'/rust in their piston grooves which will eventually break the rings. 3. Pin hole in the heat exchanger ............ Empty/drain the raw water side, block/plug both inlet and outlet of the fresh water side, then fill with water, apply pressure to the fresh water side via the radiator cap pump .... watch for the eventual leakage of water from the fresh water side to leak into the raw side. hope this helps.
Also, if you have a fresh water connection
to a domestic hot water heater, the leak could be in that line. We recently experienced a catastrophic failure of one of those lines, the failure was MINE in NOT replacing the 20 year old hoses sooner when I did all the rest. See reply #7 at: http://c34.org/bbs/index.php?topic=3769.0
to a domestic hot water heater, the leak could be in that line. We recently experienced a catastrophic failure of one of those lines, the failure was MINE in NOT replacing the 20 year old hoses sooner when I did all the rest. See reply #7 at: http://c34.org/bbs/index.php?topic=3769.0
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