Thermostat ?

[nico105]

Is there a need for a thermostat on a seawater cooled Yanmar 3GM30? It is nto a closed system. I now have one. I have not installed it and was thinking about the need for it because it is not a closed fresh water system. I don't know? temp is right at 100degrees, and does not fluxuate as it.
any knowledge is appreciated. Thank you in advance, David

[Chief Engineer]

100 degrees is too cold for the engine.

I will not go into a long dissertation as to why it is a bad idea.

[Opie91]

You need a thermostat even in a raw water system.

Is that temperature 100 C or F? The reason I ask is that the salt in salt water will crystallize at 165 F (74 C). So 100 C would be not a good thing. I am not really familiar with your particular engine, but all of the raw water cooled thermostats that I have seen are 160 F or less.

Also you do not want 100 F either (if the gage is right), the engine needs to be a little warmer to allow for a better fuel burn.

Here is the link for Yanmar FAQs:

FREQUENTLY ANSWERED QUESTIONS