Motor has no t-stat so gauge will always read low...better to install a water pressure style..
Bingo!
Thinking about the why behind the pressure gauge vs thermostat, conversations we have had herein, maybe that's the reason pressure monitoring became popular in the first place. I installed a temp gauge on my recently purchased old boat rather than a pressure gauge. The fact wound up in conversations herein. I got replies from the offshore guys about knowing that your cooling system is degrading and on long trips in big water that is really important and pressure could tell you that when temp couldn't....ahead of time. Made sense!
Somewhere back in the cloudy mist of my past, I remember drilling and taping the water jacket cover on one of my engines and installing a tap. May have been on the mid 70's 70 hp Rude I had. Bought it used, seller said it was "hot"...meaning it ran the boat at a good clip, but that turned out not to be the reason.
Back then I never did anything to my engines but change plugs; had no boating forums to tell you what you needed to maintain and all. It had a T stat but no warning instrumentation. Apparently stat had started intermittently sticking shut and one day it decided to stay stuck on a WOT run down a lake. After $1k worth of machine work and parts back in the 70's, and a lot of work on my part to get it back together and running....never did that before on an outboard, I decided to monitor my cooling....that's about all I remember.
