Temp gauge moves with engine speed...

[johnnyfamunda]

Hi All took my boat out for the first time in 2 years and the temp was normal between 160-180 while traveling through the no wake zone, once I brought the boat up to speed the temp gauge would drop below the 100 degree mark and then would shoot up to 225 and then move back and forth while at speed only when at idle did it seem to show the correct temp. I have a 2005 135hp Volvo 3.0 liter. ​I have grounded the wire and the gauge pins itself so I am thinking temp sensor. I just ordered a new temp sensor and will try that as soon as it gets here but wanted to see if anyone else had an explanation. Thanks in advance for any help.

 

[Bondo]

Ayuh,.... Welcome Aboard,..... When was the raw water impeller last changed,..??..??

My guess is it's beat, 'n needs replacin',....

 

[j.4knee]

You could also be getting air into your cooling system.

 

[johnnyfamunda]

Put in new sender still doing the same thing, took IR thermometer and engine is getting hot when driving at speed when speed is dropped engine cools back off. The temp gauge drops to 100 when driving at speed and once I slow down it shoots up to 200 until the engine starts to cool at which point it drops back to 160ish...

 

[rkilpa]

Bondo knows.....

​Check your impeller. It sounds like you will find pieces of it blocking the bypass passage of the thermostat housing and the little passages that go to the risers.