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Discussion Starter · #1 ·
I have a 1989 Universal M2-12 that over heated. When I started researching the cause I found the Fresh Water Manifold was empty. I refilled it and ran the engine without it overheating; however, the next time I checked the water level it was low again. I can't determine where the water is leaking. No water found in the bilge. No obvious leaks on the Manifold, hoses, block or Heat Exchanger. No water in the Oil. Is it possible the Heat Exchanger is leaking internally and the water is exiting out the Raw Water discharge? If so how could I determine this? I'm not a mechanic and only know what I've read in the owner's manual and online. Any input would be greatly appreciated. Thanks...... First time user of SailNet!
 

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skipper...
Try to rig up a wee long line that you can connect to the primary (jacket) coolant, tie the line up high in the engine room or even up on to deck, tie it off firmly and fill the line to the brim to give it some measure of pressure head. Now with motor off, watch the fluid level. Does it drop over time?
Do you have a wee picture of your motor you could post? I think we could figure out where to connect the makeshift hose.
.
 

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Could be the signs/symptoms of:
a blown head gasket ... the cooling water is being 'sucked' into the combustion chamber during a 'downstroke'. When this happens there is usually some 'blackness' to the fresh water in the fresh water cooling loop ... it can also be tested by fluorescing dye and black light for carbon monoxide/dioxide in the cooling water.

If the fresh water circuit is also cooling the exhaust manifold, could also denote a pin hole in the manifold ... water also getting into the combustion chamber.

Whats the exhaust smell like? .... does it have the faint sweet smell of 'antifreeze'?
 

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Discussion Starter · #4 ·
skipper...
Try to rig up a wee long line that you can connect to the primary (jacket) coolant, tie the line up high in the engine room or even up on to deck, tie it off firmly and fill the line to the brim to give it some measure of pressure head. Now with motor off, watch the fluid level. Does it drop over time?
Do you have a wee picture of your motor you could post? I think we could figure out where to connect the makeshift hose.
.
Thanks to Rockter and RichH for the response. I had a mechanic come to the boat and we were able to pressurize the raw water side of the system then removed the fresh water manifold cap and you could hear the air bubbling in the manifold. Conclusion was that the only place the fresh water and raw water meets is in the Heat Exchanger so we're pretty confident that the Heat Exchanger needs replacing. It would explain why I couldn't locate any water as it was probably exiting via the raw water discharge. The vessel is a 1989 and the Heat Exchanger appeared to be old as well. Thanks again for the replies. SailNet appears to have some very knowledgeable resources available.
 

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Skipper :

Good work. I guess a new or used heat exchanger will fix it. it's good you traced it. The motor would have overheated something awful in the end.
I guess it does not have to be the original heat exchanger either. You could perhaps adopt another model to fit, assuming it is big enough to shift the heat.
 
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