I have always been wondering if I have a good T-stat or not in my 18 but don't have a temp gauge..until now. I put a tune in my truck to help with shifting and towing and now I can watch the programmer for the engine temp. Today I took off my winter tires and put the summer tires on then ran them down to put in storage. The outside air temp was 45F and on a flat road with cruise set at 60 my truck runs right around 210. I coasted down a short but steepish hill and the temp dropped to 199 then when climbing up the other side it jumped up to 220 but most of the time it was around 210-215. Is this the temp it should be running at or should I look into it further? I have late 2018 build where my truck came with yellow coolant and an aluminum oil pan so maybe I got a better T-stat also??? one can always hope.

 

The Thermostat could be a little on the hot side but still the temps are not overheating with cooling running under pressure control.
There has been a design change in the Thermostat.
If you feel uncomfortable with the present temp, change to a new one to see what you get, for the cost of it. Use only Ford part to get any benefit.
Basically, the Trans runs in the same temperature range as the cooling system.
The engine uses a CH Sensor on the rear of the passenger side Head to cover the wide temp ranges involved. It mounted in a Blind hole in the head.
The engine coolant is a computed value as there is no coolant Sensor in direct contact with the coolant.
Don't forget, there are shutters in front of the Radiator, in this game.
Good luck.

 

That sounds about right for a stock, non-performance, thermostat. When mine failed, it failed in a partly open state. The engine took a little longer to warm up and since most of my driving is in-town, and short distance, I didn't notice there was a problem until I took it out for a longer drive. Mine, at the time, normally ran about 208-214 while cruising on longer trips and would bump up to about 220-223 going up hills. When my t-stat failed, I'd see cruising temps at about 218 and >230 going up hills. My engine never actually got hot enough actually over-temp but once it did get to about 240 degrees. I replaced the t-stat myself, using the t-stat from Motorcraft. Not all t-stats that are listed as compatible with these trucks are actually compatible. The ones from Motorcraft actually are compatible and are good units. Motorcraft RT1252 is what I have in my pickup. It's the OE temp but it works quite well.

 

I know the temp is a calculation but is close to the actual temp. My 07 mustang had the same thing and I relocated the sensor into an actual coolant port to get real coolant temps from it when I installed the supercharger. It could be the different sensor or the fact that I thought it would be running 190-200 and not 200-210. I'll keep an eye on it and see what it does as it starts to warm up, I have a new t-stat I just don't have the time to install it now....too many projects to get done before it gets warm out. Thanks for the replies.

 

That is a little on the warm side. My truck with the original thermostat usually runs in the 193-199 range, a few degrees higher in hot weather. My transmission temp usually displays about 2-3 degrees lower than the engine temp.