Water temp gauge

[onthehunt49]

Boat giving me little issues this year, but running great once started
Water temp Gauge worked last year.
But not this year. MID 95 5.7 mercruiser

Any ideas where to check?
I grounded out where it connects to engine. Gauge pegged out and went back to zero ?

Thanks.

 

[Fun Times]

Make sure the engine is actually getting up to full operational temperature of your thermostat temp range… if the thermostat is stuck open, the engine may not reach temp and won’t move the gauge up making you think something else is wrong.

 

[onthehunt49]

Make sure the engine is actually getting up to full operational temperature of your thermostat temp range… if the thermostat is stuck open, the engine may not reach temp and won’t move the gauge up making you think something else is wrong.

I have run it most of day. Pulling one of those couch/tube things with grandkids. At least hour or two steady. Temp gauge hasnt moved.

 

[Fun Times]

I have run it most of day. Pulling one of those couch/tube things with grandkids. At least hour or two steady. Temp gauge hasnt moved.

Did you physically touch the engine to feel if the engine came up to temp? Your best bet to test the actual temp is to get yourself an affordable Infrared Laser Thermometer gun and point it all around the engine to see what the temperature really is...You can find these temp gun readers just about anywhere nowadays,

https://www.harborfreight.com/search?q=Infrared%20Laser%20Thermometer

Also need your engine serial number and maybe a photo of your thermostat housing to help know if you should have a 140 or 160 degree thermostat on your engine model as it could be either or...