Gen 2 overheating(?)

MDD

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Hi everyone,
Strange observation today on a road trip from SC to FL. I noticed that on small hills in SC or even bridges going up an incline that the numerical temp would indicate as I went up the incline. I doesn’t Indicate with the numbers at all normally. Typically the temp number would pop up ~230F then at the top of the hill or on the down slope, the temp would decrease with 10 sec to 225-226F and then the numbers would disappear. The max I saw was 236F. The temp gauge would not move at all or so imperceptibly as to be useless (So, must be “normal”, right?). This occurred in 10th gear and during boost. I replicated later when gently passing in boost but not dropping gears. I could not replicate when locking out gears and really hammering the throttle.

Coolant was at warm max, front shutters completely open and this all occurred between 75 and 85F. Truck had just me and maybe 100 lbs of gear. Truck is stock. Also, fan seems to work in both low and high speeds. The number does not pop up at idle with AC. I tested with a 10 min idle at a gas stop after coming off the highway. If the indicator pops up at >226F then the engine must be running ~220sF. Seems pretty warm. No CEL or other lights.

I searched this forum and didn’t see anything. On a wider search of the F150 forums I found many instances of this. Most times it seemed that it was after a cam phaser repair. I had mine repaired under warranty in Feb and have road tripped a couple times and have never seen this. Many on that forum report multiple parts changing and sometimes fixing and sometimes not. I’m not going down that road. My local dealers shops are not very competent in my experience. I have a local shop I like but this will be very hard to replicate/diagnose since it requires an extended road trip. And most ford shops apparently say this is “normal” blah blah blah.

Popular theories on that forum are thermostat not operating correctly or blockage in the cooling system. Some guys apparently live with this for months. Hoping ya’ll can provide some insight!
 

FordTechOne

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If you have an overheat issue you will see it reflected in the temperature gauge. If the temperature increases outside the range of normal operation, a DTC will set.

It sounds like you are monitoring Cylinder Heat Temperature (CHT), which is completely different than Engine Coolant Temperature (ECT). The purpose of the CHT sensor is to act as a backup for the ECT, since the ECT will not indicate an overheat condition in the event of substantial coolant loss.

The CHT indicates the temperature of the cylinder head itself, not the coolant. For that reason it will read higher under load. The readings you're seeing are completely normal and nothing to be concerned about.
 

MDD

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Hi @FordTechOne thabks very much for your quick reply! Your continued contribution to this forum is extremely valuable and fantastic!

To be clear, I’m not monitoring anything other than what the stock cluster gives me (e.g. no forscan etc). When I was mentioning the temperature numbers, they appear directly above the coolant indicator gauge when temp >225F. Thus, I believe this is the actual coolant temp as a warning when it gets above 225F.

I hope this is clear. Maybe I am wrong in my assumption of what this number is but if it’s cylinder head temp that makes no sense to me to show above the coolant temp only sporadically.

Given this info, is your response the same?

thanks again and I’m interested if others have seen the same. Also, disconcerting that this would be the first time in 2.5 yrs I would see this. Seems like more than some new issue to me and NOT “normal”.
 

FordTechOne

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That’s for the clarification. I thought you were referring to the CHT reading in the measurements display.

As long as the temperature gauge doesn’t turn yellow or red, the coolant temp is still within specification. Note that the thermostat isn’t fully open until 217 degrees, so 220’s/230’s is not out of the ordinary under low RPM/high load. Did you drive the same route under the same conditions (temp, load) before the repair without having the coolant temp appear?
 

MDD

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Before the repair I have driven the same route on I95 several times and it never happened before on the small bridges where it did yesterday. It has never happened since the repair till yesterday either and I drove this route back in July. I’m not sure it’s connected to the repair work done back in Feb. Maybe failing thermostat???
 

FordTechOne

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Definitely strange that it didn’t always do it; thermostat is a possibility. You may want to start by asking the dealer if they used a vacuum coolant filler and bled the system during the last repair per the workshop manual, there could be air trapped in the system.
 
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