Re: installing new thermo switches
Glass.... The "Thermo Swich" as you refer to it, which sits in a hole under the water jacket plate of the cylinder head, is actually a heat sensing unit, most commonly called a sender or sending unit.<br /><br />It has a metal plate on the foremost end of it, seating up against a rubber type barrel assy, with a "Tan" wire protruding from it, the end of which has either a plug in or knife type connector. I describe this so that we are both speaking of the same item.<br /><br />It's purpose, when the engine overheats, is to ground out the sender unit to the cylinder head. This completes the ground circuit leading to the warning horn which in turn causes the warning horn to sound.<br /><br />There is no "Temperature" switch on either cylinder head, that is nothing of that nature would be standard equipment with the purchased engine when new.<br /><br />If there is a temperature gauge on the boat, then perhaps, when you refer to a temperature switch, you are refering to a brass unit that is screwed into a "L" shaped bracket..... in which case that "L" shaped bracket is held to the water jacket cover by one of the retaining bolts. That brass unit would indeed be a temperature sending unit which would constantly be sending a signal to regulate the reading of the temperature gauge.<br /><br />The end of that brass unit should not be touching the cylinder head as that usually creates a false reading (too hot) on the gauge. Adjust it so that there is a .010 clearance between the brass unit and the cylinder head.<br /><br />Hopefully this is what you are referring to. If not, I'm somewhat at a loss.
