The thermostat in my 1960 Evinrude 5520 5.5 hp is
stamped 143 degrees. The replacement I got says
163 degrees.
What is standard?
Did these units tend to run hot?
Thanks!
Your 1960 5.5hp does not run hot, its exhaust cover is water cooled unlike earlier models from the 50s. I wouldn’t worry about the markings on the thermostat, designs have changed a bit over the years, but that won’t affect the operating temperature of your engine much.
You don’t want your motor temperature much over 160 F. otherwise salts and minerals in the water leach out and start building up on the water jacket surfaces. Newer motors and four strokes commonly use the 163 Tstat so I’d take it back and get the proper 143 one.
The older brass stats had the year of manufacture stamped on them under the seal. This was handy for determining if they were original or had ever been replaced in their lifetime. New ones seem to be made out of some kind of stainless or plated metal and carry no date stamp. That’s the price of progress.
I am the member who sent the OMC/BRP thermostat to Bucaneer. It is a full stainless steel part from a later model motor. The earlier thermostat #378065 SS to #5005440 I believe. I agree with Mumbles you do not want to be too hot or risk deposits in your cooling system from salt water. Fleetwin I sent it with some other parts that I figured he needed to replace in an engine of that age to make a good running and idling engine.
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