1990 force 150hp overheating

I've recently purchased a 150hp force 1990 installed the engine on a 19ft bayliner enigine runs great and strong at higher speeds the engine overheat horn goes off at lower speeds it seems to be fine after overheat horn sounded I cut the engine let it cool off returned to shore and checked compression wich was the as when I bought the engine(120psi per cyl.)I am curious since the boat has no temp gauge could the temperature switch be faulty and setting off horn at a lower temperature than it should? Is there anyway to test what temp. switch is closing at? Is possible to install a temp gauge? Thanks!

Re: 1990 force 150hp overheating

You can test the temp switch by removing it and placing it in pot of water on the stove. Place a thermometer in the pot so you can monitor the temp. Connect a volt meter, set on continuity, to the temp switch,. Turn on the burner and wait for the meter to tell you when the switch activates.<br /><br />Rather than adding a temp guage, which will show you that your engine has overheated, after the fact, you should add a water pressure guage. Water pressure guage kits are about $50 and easy to install. It will tell you as soon as you have a lack of cooling water.<br /><br />But the first thing I would do is to replace the water pump impeller, or possibly the entire water pump. The first thing I do to any motor I buy, is replace the impeller.