Calling all Coolant System Gurus
 

Over heating issues.
2012 Escape 2.5L

Driving on the hwy one day it over heated and went into limp mod.
Threw code P1299 (Cylinder Head Over temperature Protection Active)
After a little research, replaced the CHT Sensor and the Thermostat.
Filled up the cooling system, burped it and everything seemed fine. No leaks, getting heat inside. Drove it 20 mins down the hwy and back all good.

Next day same thing, After 30 mins on hwy it over heated, limp mod, code P1299.
Thinking it may be a warped head / head gasket. I pulled the plugs, Not one “washed / clean” plug. Compression test showed 155-160 across all cylinders. No coolant in oil (milky oil). No trace of oil in coolant. No “white” exhaust. Thinking it was the water pump, replaced water pump. Filled with coolant, burped it. Again everything seemed fine. Took it for a 20 min drive and again everything seemed fine temp gauge stayed glued at normal. At this time I did a Combustion Leak Test at the overflow tank just to once and for all eliminate the head / head gasket.
Hooked up a ForScan and read live data while I drove back and forth on the hwy for over 2hrs. Coolant temp stayed at 98-101c (208-213F). I pulled over several times to check the overflow tank and do a Combustion Leak Test at the side of the road. Everything was good Temp didn't move, lots of heat inside even at idle. Drove home and parked it.
After a couple hrs I took it for a rip and 10 mins down the road it over heated. Temp gauge pinned / coolant temp 125c (257F) / No Limp Mode / No Code. Went back home and by the time I got there temp dropped back to 110c (230F). I went to do a Combustion Leak Test and the coolant over flow tank was full. Opened it anyway and about a liter came out. The odd thing is the coolant was not hot, it was lukewarm to the touch. Sitting there idling this whole time, the temp dropped back to normal. I topped up the over flow and went for a rip, 20min later ALL NORMAL.

As it sits now:
New:
CHT Sensor / water pump / thermostat

Checked:
Head / Head gasket – multiple times and multiple ways
Heater core – no smell of coolant and lots of constant heat inside
No Leaks anywhere

Still overheats –What am I missing?

Thanks in advance / sorry for the long post
Ken

I would bet you didn't pay attention to if the cooling fan(s) were operating ! !

The cooling fan relays have had some problems. If you check the relay and the contacts you may get your answer.
For now , just install a new one and make sure the contacts it plugs into are clean and tight.. Let us know how you make out, thanks.

Hanky, thanks for the quick response.
That would make sense at hwy speeds (lots of air flow) But I'm pretty sure I saw on the ForScan the cooling fan status was 'On' at one point.
Regardless I will check and test / replace the relay(s).
thank you for your input

Checked Cooling Fan System. No Fault found.
Relays and Fuses tested and or ok
Cooling fans are working
the search continues........

Do you actually hear and see the cooling fans working?
Many tests only verify that power is getting to them, but do we know for sure that they are actually working?

hanky,
Yes, a very good point.
After testing the fuses and relays, I hooked up a jumper wire at the relay / fuse box. Both Hi and Low are working fine. (at least from the fuse to the fan)
I then went for a quick test run. The temp gauge went up to normal and stayed there. ForScan said coolant temp went up to 96-98c and held stead.
Toward the end of the run, ForScan said the Low Speed Cooling Fan was ON. I stopped at the side of the road and verified the fan was ON low.
Going for another run today, fingers crossed.