can I use the temp sensor on top of the water pump for my autometer water temp gauge?

S4 TII

 

That's a thermoswitch, so no.

 

Tempeature sending units are heat sensitive resistors. Some have positive temperature coficients, some have negative temperature coficients. In a pos. the resistance rises as the temperature increases. The neg. is just the opposite. The resistances also vary between different sending units. Manufactures carefully match the sending units to the gauge. If the stock sending unit works you are lucky. Get the sending unit for your particular gauge. Use an adaptor if it won't screw into the original hole....