Re: 25 hp evinrude thermostat
You should replace that 'stat ASAP, it is needed. Remember, tstats control min temperature, not max.
Without getting into mechanical theory, the t stat is needed to keep the engine running at an optimal temperature, preventing severe damage to the piston and cylinder wall.
Some motors will actually overheat. The necessary cooling water from the water pump is never quite filling the block, hence the top cylinder overheats. Some cooling systems actually rely on that t stat for a restriction, since the water is exiting quicker than it is being replenished. Removing the stat is also horrible for a water cooled rectifier/regulator.
The rings will wear out quicker (not by much, but quicker none the less), and carbon will build up as already stated.
You have to have faith in the OMC engineers, they get paid the big bucks, and if the bean counters could have talked them into scrapping the t stat, they would have Im sure!
Bottom line, I would replace it.
