[NoBones]

On my 200 HP V6 Merc I added an additional temp sensor.
One on each bank, plus the water pressure. I used the
Merc guages which are made by Teleflex. There is the tan wire in the harness for the 1st temp, then I used the spare
(I Believe) brown with yellow trace wire for the second sensor. This way you can monitor both banks on the engine.
The only noticable difference is the add on sensor runs a fuzz higher then the oem sensor. After my water impeller starts to age I notice that my running temp starts to rise more then a new impeller. That is one reason to change the impeller at least once a year. There is a date code on all impellers, just look for the raised number on it inside the blades "circled", that is the year it was manufactured.
Hope this helps, Ken