Need a lot more detail to go on. What is "it"? A warning message on the instrument cluster? A reading on a scanner? A diagnostic fault code? Does it appear the engine is really getting too hot?
What about the repairs? Which sensor was replaced, and was it damaged in the crash? Besides the radiator, has the grille and body been repaired? Of particular interest, there should be a rubber seal under the front edge of the hood. That prevents cooling air from bypassing the radiator. That seal doesn't come with a new hood, but it will typically be left in place with a used hood from a salvage yard. Is that seal in place? Even when it comes with a used hood, it gets removed during the painting job.
Another overlooked cause of overheating is openings in the "core support" that are normally filled with some component or cover. The core support is the sheet metal plate the radiator is mounted in. Sometimes people are so interested in getting the vehicle drivable, that they wait and plan on installing those parts later. Holes in the core support will allow air to bypass the radiator, and it is possible for air to flow through the radiator, then return through those holes and go through the radiator repeatedly as it gets hotter and hotter.
The same is true if a needed shroud is not in place behind the radiator. Those force air to be drawn through the radiator by the fan.
You didn't say under what conditions the overheating occurs. If it is only at low speeds, and after driving a few minutes, the cooling fan may be missing or not working. At highway speeds, natural air flow will keep the engine cool. If the overheating only occurs at higher speeds, physical blockage is more likely. New, and often used radiators come with plastic plugs on the hose connections. In one case, they were painted black, and one was overlooked by a coworker. The hose was able to be installed over that plug, which blocked coolant flow, and, of course, resulted in immediate overheating.
Your model is too new for this, but for the benefit of others researching this topic, corroded cooling fins on a used radiator will cause running hotter than normal, more so at higher speeds where more heat is developed, but air flow is ineffective due to the missing fins.
Finally, consider that a lot of engines today need to have their cooling systems "burped" to remove trapped air pockets. Air typically pools under the thermostat where it prevents it from opening. Thermostats won't open in the presence of hot air. They need to be hit with hot liquid. There's three different engines used in your model. You need to list which one you have when asking an engine-related question, and be sure to list the transmission type and two or four-wheel-drive when those variables must be known to look up the right service data. Look for a bleeder screw on the thermostat housing. If you find that, open it while filling the cooling system. If you don't have a bleeder screw, look for a sensor or threaded plug on or near that housing that can be removed during filling. If you have a sensor that can be removed, best practice is to only unplug it while the ignition switch is off. If it is ever unplugged while the ignition switch is on, that will be detected as a circuit defect. A diagnostic fault code will be set that will often confuse additional or future diagnostics.
Many Ford models are extremely difficult to get the air out of the cooling systems. A number of special tools have been developed to address this. A common one is a large funnel to attach to the radiator that can be kept full as air is expelled. That prevents air from going back in.
If you get a warning message right away before the engine has run long enough to get hot, we can assume it's a problem with the warning system. Feel the upper radiator hose. It should get too hot to hold onto for very long, but it won't burn you. If you can hold the hose for about five seconds, the engine is likely not overheating. This is the time a scanner is needed to view live data, in particular, coolant temperature. Normal is typically close to 195 degrees, but for some models, normal operation lets the coolant get as high as 226 degrees before the electric radiator fan turns on. I don't like to see that, but when the system is designed that way, there's nothing we can do. I don't like to see coolant temperatures get over about 210 degrees. If the scanner shows coolant temperature to be minus 40 degrees, that is a default on most models when there's a break in the coolant temperature sensor circuit. Some Ford engines no longer have a coolant temperature sensor. Instead, they use a "cylinder head temperature sensor". Operation is the same, but it will be listed differently on the scanner's list of sensor values.
Under normal conditions, the -40 degree default is the result of a broken wire or a corroded connector terminal related to the temperature sensor. This is true of all temperature sensor circuits. Temperature sensors are the least likely cause of this. Temperature sensors have an extremely low failure rate because there is just one component inside of them. The one notable exception is Ford had a huge failure rate with their coolant temperature sensors in the early 1990s. Those sensors are long gone. Today, more are damaged in crashes than fail on their own. Also look closely at the connector terminals on the sensor. They're pretty tiny, and every mechanic has bent one over at some point.
An additional clue to a break in the coolant temperature sensor circuit is the electric radiator fan will turn on as soon as the ignition switch is turned to "run" or as soon as the engine is started. That is another default condition. The Engine Computer can't know actual engine temperature, so the fan gets turned on in case the engine is running too hot.
Another clue is to feel the temperature of the air from the heater ducts. That air should not burn your hand. If it does, the engine likely really is getting too hot. If that air is cool, the coolant isn't circulating properly.
Let me know what you find with as many of these clues or checks as you can, then we'll figure out where to go next. I left out some other overheating causes from this story related to engine trouble because it's pretty certain this is related to the crash damage or repairs.
Sunday, January 12th, 2025 AT 9:16 PM
