Salt water cooled to Fresh water cooled

[Boxertwinjeff]

Hi, I have a Yanmar 3GMD, would it be an expensive process to
convert it to Fresh water cooling, and would it be worth doing, like
what are the pros & cons... Cheers.

[NCboatrx]

If this engine has been used in salt water for an extended period I would not convert it to heat exchanger cooled. There is likely to be some corrosion within the water passages of the engine and it is possibly more cost effective to just use and enjoy the engine as it was built and when (if?) it eventually fails, to replace it with a more modern and efficient one. Remember that the corrosion aspect of a raw water cooled engine is controlled by temperature so make sure that the correct thermostat is fitted.

[a64pilot]

That is where I am at too, you would spend overhaul money to convert and it may not do much for you

[roverhi]

You'll need a heat exchanger, raw water pump and bracket, and a dual pulley for the crank. Might be some other small parts and water hoses.

I'd keep that old hunk of iron going as long as I could. New engines are going to electronic injection. The last thing I want is electronics responsible for keeping my diesel functioning. Switching to freshwater cooling should stop the progress of any corrosion that's already occurred making internal wear what will determine life of the engine.

[Boxertwinjeff]

Thanks for your input guys!

[Jim Cate]

If you do decide to go ahead, I'd surely give it a very thorough acid washing to clean out corrosion products and (more likely) salt mineral buildup. The latter is what plagued our previous raw water cooled BMW D35.

I reckon that the advantages of FWC would be worth it if the engine is reasonably young and in good nick. Should increase longevity, and the ability to run hotter is a good thing in many ways.

jim