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Old 08-07-2015, 22:15   #1

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Yanmar 3gmd conversion to fresh water

In all the listing I can find the 3gmd does not list it as fresh or raw water cooled. All other models do. Is there a difference between the 3gmd & 3gmf other than raw or fresh cooled. I Do a visual inspection on my 3gmd it appears all of the recirculating pump & peripherals will bolt right on the motor OK. Then add an exchanger & reroute a few cooling lines & I am good. My boat has always been a Lake Michgan boat but now I am heading to the ocean & I want to convert to freshwater cooling. Any & all advce & comments are appreciated

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Old 09-07-2015, 04:42   #2
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Re: Yanmar 3gmd conversion to fresh water

To best of my knowledge the GMD was the first of GM series and the D stood for Direct, as in cooling, but I will stand corrected. There are many thousands of these engines still giving reliable service in saltwater with regular Anode attention. You will have to change your thermostat to 145f for salt water if a fitted with a hotter type, then it will be still going strong when most of use have gone.

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Old 04-10-2015, 19:35   #3
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Re: Yanmar 3gmd conversion to fresh water

I have a Yanmar 3GM on my Freedom 33 and it was converted to freshwater cooling. ItS really quite simple. You can get an external heat exchanger which with a couple of brackets bolts on to the back of the engine using the two top housing to engine block bolts. an extra water pump also needs to be added. This pump is for the raw water and the original water pump">raw water pump runs the frsh water cooling circuit. . Also will need a new pulley available from yanmar with an extra space for the belt for the added pump. Then just run the appropriate hoses to the heat exchanger, 2 for the engine coolant and two for the raw water circuit of which on of these goes to the mixing elbow on the exhaust. My set up works great. If you want pictures , diagrams etc, just PM me and ill try to provide them for you, Rick
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Old 05-10-2015, 02:34   #4
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Re: Yanmar 3gmd conversion to fresh water

Midnightsailor, I would interested in knowing how you dealt with the thermostat when you did your freshwater conversion.
All men dream: but not equally. Those who dream by night in the dusty recesses of their minds wake in the day to find it was vanity: but the dreamers of the day are dangereous men, for they may act their dreams with open eyes, to make it possible. T.E. Lawrence
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Old 07-10-2015, 20:54   #5
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Re: Yanmar 3gmd conversion to fresh water

Not sure what your concern is, I just used teh same thermastat and housing that is use on the 3GM F(fresh water cooled) so I am now able to run with a higher operating temp than the raw water cooled engine did( I for get the exact temp but I believe it is about 180.degrees. let me know if this helps or if I can provide other information, regards,Rick
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