So I think my water temp gauge is not working. Is there a way to determine if it is the gauge or the sending unit without just replacing one or the other? I am guessing somewhere between 160 and 180 at cruising speeds is a normal temp. I would also expect it to rise while slowed down to idle. My temp gauge never reads over 130...therefore i assumed it was no good. But then I thought maybe it could be the sending unit????