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Last season the temp gauge read 160 during idle or no wake running. Under a load and running 120. Ambient water temp made no difference. Impeller is good (changed and checked)

Before I go digging too deep, your thoughts

I will check connections at the gauge terminal, then the gauge sending unit (on the 5.7 it's located at the thermostat housing correct)?, After this, then...?

Thanks

2001 246
5.7 GXI (B)
315 hours

You can always double check your gauge by using an IR thermometer and aim it at the thermostat housing.

Not sure what thermostat is used in your engine but it will be either 160°F or 140°F. You may want to check its function.

Yea your tstat could be stuck open. Should be a 160. Some had 140s in them like mine does and they came out with a bulletin to change it to a 160 so the oil gets warm enough to get rid of moisture in the oil.

I will check the tstat, but this weekend the temp gauge never moved off of 100. This screams gauge or sender to me, but i'm not sure.

I'm leaning on the thermostat stuck open.
Same thing happened to me on my Mercedes. Had no heat in the winter time.

Forgot to revisit this with those who helped out.

The previous impeller came apart and I changed it out. After removing the T-Stat I found the remains of the impeller vanes in the T-Stat and throughout the housing. Solved! Thanks

Thanks for the followup, PilotMike - it's sure to help someone else down the road