My thermostat was stuck as one issue in my motor overheating (my impellar was also fried) A mechanic friend that used to service Mercruisers claims that it will be fine w/o a thermo. Anyone else doing this? I was told that it simply keeps the motor temp within a certain range, and that it should cool just fine without it. I don't want to screw anything up. Thanks

The thermostat keeps the engine at a certain temp for a reason; the tolerances can get way off if it runs way too hot or way too cold for a long time (in this case, cold) and you would lose a lot of power, not to mention I'm pretty sure its not good for the life of the engine. <BR> <BR><a href="http://www.correctcraftfan.com/forum/forum_posts.asp?TID=3870&amp;KW=thermostat" target="_blank">CCFan post</a>

well it wasn't a mercruiser but on our first boat (seaswirl) it would never warm up. come to find out the thermostat was stuck open, basically the same as not having one. never had any issues performance wise. that was my experience with thermostats in boats

There are instances where you can run without a thermostat but a start and stop boat would not be one of them. Normally a restrictor plate is put in, in place of the thermostat. It almost every situation using a thermostat is far superior to not having one. <BR>With out one it will cool just fine, like your friend said, but it will not warm up well at all. That means that you get less power, worse fuel consumption, and more engine wear. Because it's running without the temperature control you get less consistent power for starts and speed control. <BR>Use a 160 degree replacement of good quality. If you had a cooling issue with lack of water flow past the thermostat you could put a 1/16"hole, or smaller, in the thermostat metal to the side of the valve. That ensures flow past it so it will open at the right time. You will be surprised how much longer it takes to get to operating temp with even a hole that size.

Common sense says use a thermostat.

I ran mine without one while waiting for a new one. You will burn MUCH MORE FUEL. Enough said.

Thanks guys, I'm ordering one tonight

Without a thermostat, you will lose power and use more gas.