Temp gauge spiking.

[TheFriend]

01 Response LX. 

sometimes temp. Gauge works and doesn't work. Typical. Was doing some maintenance today. Hooked it up to hose and started engine. Temp was at 160*+ as soon as i started it. Let it run for 15 mins. Temp got all the way to 220*+. Turned it off a couple times and it temp ended up past 240*. Everything seemed to run fine. Water was coming out of exhaust ports(new water propeller this year). Risers on exhaust manifolds were warm but the manifolds themselves were cool to touch. Water pump was cool to touch. Most lines except 2 were cool to touch. The main big line running into motor and the heater lines were only lines that were hot. So it seemed to be fine. When i turned everything off. All gauges reset themselves except the temp gauge. It stayed at 240*+. Could the gauge be calibrated wrong? 

Edited June 19, 2021 by TheFriend

[UWSkier]

Likely the gauge is bonkers or you have a bad ground. 

[TheFriend]

8 hours ago, UWSkier said:

Likely the gauge is bonkers or you have a bad ground. 

I just installed an add a battery system. I replaced all ground connectors at the battery end. Im haven't looked at the gauge side. 
 

thanks. 

[justgary]

It is possible that the sender is bad.  You can test it with an Ohm meter.

The first thing I would do though, is clean every connection under the dash.  I would also clean and gently spread the terminals in the Cannon plug at the engine, and then the engine grounds at the back of the heads.

[TheFriend]

27 minutes ago, justgary said:

It is possible that the sender is bad.  You can test it with an Ohm meter.

The first thing I would do though, is clean every connection under the dash.  I would also clean and gently spread the terminals in the Cannon plug at the engine, and then the engine grounds at the back of the heads.

Awesome. Thanks for the info. Im terrible at electrical stuff. I will poke around and clean up some connections. Try to test some things with meter. I have a friend that pretty good with this stuff. He kind of helped me along with this Blue Seas kit. Thanks again.