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changing cooling from salt to a closed system

1570 Views 5 Replies 6 Participants Last post by  floatsome
hi i have a irwin 38 sailboat from 1971 , my question is this i have a yanmar 20hp salt water cooled which i want to replace, in a chance meeting i have been offerd a used 30 hp yanmar which is a closed water cooling system ,is this going to be a hard job to get this system in my boat or better to convert the engine to salt water , i think i just get the bare engine no cooling parts , any pointer would be great , this is a project were i will do all the work myself and save money
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The heat exchanger is usally mounted on the motor SO it should come with everything
hi i have a irwin 38 sailboat from 1971 , my question is this i have a yanmar 20hp salt water cooled which i want to replace,
Want to or need to (both are god answers)?

Measure the two distances between the motor mounts. Are they the same width on both, are they the same length distance on both.

On a raw water cooled engine the raw water goes to the water pump, on a fresh water cooled engine, the raw water goes to the water pump. Exactly the same except on raw water cooled, the raw water goes through the cooling parts of the engine and on fresh water cooled the raw water goes through a cooling chamber and anti freeze (or something like it) goes through the cooling ducts of the engine.

OK - very over simplified, but it might help.

This might also be of help:

Fresh or Raw Water Cooling System

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Using closed cooling brings you the benefit of a controled temperature also, independent of external water. This mean you can set your engine for proper temp and take most of it for efficiency on diesel/lub/etc ... Unless you can set your actual engine to take advantages of that, a longer life span will be too little for the work, and very arguable by others. Another important benefit, is now you can have true heated water .... RikHall did the point, check available size for engine room, mounting, etc, and consider the total replacement.
if the engine was fresh water cooled it should have the heat exchanger on the engine as tommays said. it also should have the belt driven sea water pump mounted on the engine. fresh water cooling is the way to go. the thermostat opens at a higher temperature so the operating temp makes the engine more efficient. also you put antifreeze in the system which helps prevent rust. with a coil in the water heater the antifreeze heats the water to eng water temp.
FWC adds years of life to the engine and makes winterizing much easier.
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