Join Date: Feb 2011
Location: San Francisco Bay area
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Re: High Priced "Marine" Thermostats
If your engine is fresh water cooled - it has a heat exchanger - you want a 180 degree thermostat. 140 degree thermostats are used in raw water cooled engines so salt deposits do not build up. 180 degrees is better but just won't work on a raw water cooled engine.
The 5411 is raw water cooled, while the large ones have a heat exchanger. 140F is the correct thermostat for the 5411.
Bristol 31.1, San Francisco Bay