Re: 1979 Evinrude 115 Thermostats
Either is possible. A telltale stream is normal just after the engine starts. Normally, the engine will warm up to 143 degrees, then the stats will open and keep it around that temp at idle. Usually you won't see water exiting the exhaust relief ports till the stats open, typically in a minute or so after cold starting. In late summer, when the lake warms up, it is possible that you might see 155 when idling in gear. When the engine runs cold, you get poor combustion and carbon tends to accumulate around the rings. Best to run two good stats. Since that engine is a flatback, changing the stats is not such a big deal. Also possible the pressure relief valves are not working properly. When you plane the boat out, the pressure relief valves open and the engine temps will go down a lot, maybe to 100-depening on how cold the water is.
