It's bloody cold here in Alberta at the moment and I had to make a longer highway drive yesterday. Noticed my temperature gauge climb to just over half, then move around in the 3/4 to 7/8 range for 20 minutes and then redline as I was climbing up a hill. Pretty crazy that an engine overheats when it's so cold outside. Why?

When I pulled over to let it cool I noticed the adjustable flaps in front of the radiator closed, seemed odd. It came back down into the middle, I cranked the cabin heat and fan and continued on. The rest of the trip was fine, it stayed in the middle unless I turned down the cabin fan. I had another half hour drive, quick break and then another 1.5 hour drive. Temp gauge stayed in the middle unless I turned down the interior fan from full.

Truck is 2016 F150 XLT 3.5 Eco with 188,000km. Has had a coolant flush 2 years ago and levels are all within parameters.

Any ideas on why this would be happening? Is it just too cold? Is there a way to adjust flaps?

 

Pretty sure the grill shutters being closed has something to do with. Were the cooling fans running on high speed when it was overheating?

 

Yes, the cooling fans were in high speed mode for a while. They went back to regular speed when it got back down to half.

I forgot to mention I was watching the transmission temp as well during the whole drive and it stayed in the low 70C.

 

Coolant level is okay? nvm, read the whole post.

 

I should also add.

I drove around the city in the morning and afternoon. Nothing long, 30min tops, and staying under 80km/hr basically. No temp issues. When I got off the highway yesterday and the 10 minutes to my house in -39C, I turned down the cabin heat and fan with the engine temp staying right in the middle.

Did/Does the truck just overcompensate with the flaps in such cold temps?

 

Just a thought... I've seen the coolant freeze up at very cold temperatures - ask me how I know. It will cause it to overheat as the coolant cannot flow as expected. If that was the case, and you shut it down and let the engine cool, the heat from the engine probably thawed the frozen coolant (in the radiator and hoses) and when you restarted the truck, the temps all seem fine now.... I'd check the coolant to see what mixture you have and what level of protection you have. You can purchase the little glass syringe with the floating ***** to check the coolant temperature point (may need a higher concentration of anitfreeze for temps that low). It is good the coolant level is good, but I'm suggesting checking the coolant/water mix. In my opinion, the shutters being shut won't cause it to overheat in -36C degree weather.

 

I will say I've noticed my truck running a little warmer than usual this week. I haven't noticed anything over 96°C [205°F]. Remember, it is not the actual coolant temperature you are seeing but rather an inferred coolant temperature based on the CHT sensor signal and other factors.

 

My old work van used to show both ice cold and overheating when it got this cold. Have you grabbed a coolant hose when it says its overheating? If you can hold it, its fine and may just be a glitch from the cold.

 

Thermostats seem be a problem in these years. If you haven't changed to the new style it may not be a bad idea.

 

Interesting. Either way, I touched the some of the hoses and reservoir when I pulled over and it wasn't scorching like I thought it would be. The deepfreeze should subside this week and I'll either look into the thermostat or wait until summer to do some yearly maintenance but a few people have suggested a thermostat upgrade/replacement.