Water Temperature gauge question

[PVEPANTHER]

So I finally got to drive my MM in Oregon today…very happy! Question on coolant temperature - outside temp today is 90 plus, AC on full, temp gauge sits right above half. On the freeway, doing 65 mph, it rose to about 3/4 or slightly more, and then proceeded to drop again after a few minutes. Is this the fan coming on? Coolant was replaced by the Ford dealer here in Beaverton a couple of weeks ago.

Is this about normal on a hot day?

Thanks

[crouse]

My guess is there is air in the system after then coolant change.

[blazen71]

Follow this procedure to burp coolant system

https://www.reischeperformance.com/refill.html

[burt ragio]

My coolant temp gauge after warm up stays at just a hair over half. As engine temps rise the auxiliary fan should turn on via temp sensor. As mentioned check system for air in system.

[PVEPANTHER]

Here is the update - system was checked for air, and it was OK. Temp was still rising, so fan operation was checked and it was running at 98%, so that was good. Tech thinks its a defective thermostat, that is sticking, and not opening all the way at times. New thermostat goes in tomorrow, so we shall see! Thanks for your suggestions.

Installed the Marty Tune, and its awesome!

[TORINO]

Easy to get the wrong one from the parts store. Original Motorcraft is RT-1110 188 degree. Stant 14138 is 180 degree.

[RubberCtyRauder]

....Napa 109

[PVEPANTHER]

Thanks, yes have confirmed the part number with the shop…

[PVEPANTHER]

The cooling system blues continue….while the car was on the rack, it was noticed that the radiator has a pinhole leak, that seems to spray coolant when under pressure, so a new radiator is being installed!

[MyBlackBeasts]

Classic symptoms of radiator restricted due to bugs/gunk. Pull shroud and flush/clean radiator fins with gentle pressure - not full blast pressure washer pressure. Clean the radiator and a/c condenser and then try the highway again. Good luck!