Temp guage says 225, thermometer says 180

[harrisg]

I was concerned that my Volvo Penta AQ125A/270 that is in a 16ft "83" Invader that I just bought was running hot. The temp guage was up to 225. However, when I tested the closed cooling system with a thermometer, it was actually 180, which is right where it's suppose to be. My question is, is this usually a temp sensor on the engine or a guage problem? Should I replace the defective part or just note the change on my temp guage?

 

[kwoolard]

Re: Temp guage says 225, thermometer says 180

It is probably the sending unit not getting a good ground or a loose connection somewhere between the sender and the gauge.