Engine temp spikes on highway

[DavidCola]

I have a 2019 Platinum, with 89k. I was having interior heater issues. Heat would be intermittent. My local mechanic found a tiny leak in near my reservoir tank. He said that was allowing air into the coolant system. That was fixed. Drove it for a day, and another leak develops at another hose that feeds the heater core. That was fixed. No heater or leak issues.
So now at highway speeds, 70+, my temp gauge will spike to up to 238 degrees, then back to normal within 10 seconds. I took it back in and he bleed some air out but it is still happening. He said this is normal for this engine. As long as it below 240, it is ok? Is it? Has this been happening before and I just didn't notice? I asked if the thermostat should be replaced and he said no.
BTW,,,, I called my local dealer and said they were 2 weeks out to look at it!
Thoughts?

 

[5280tunage]

240 degress, not sure I buy that. mine I don't believe mine has ever gone over 220 while towing at highway speeds gaining several thousand feet of elevation. In fact, I had been debating on putting in the 180 degree thermostat I bought over a year ago.

 

[99WhiteC5Coupe]

I have a 2019 Platinum, with 89k. I was having interior heater issues. Heat would be intermittent. My local mechanic found a tiny leak in near my reservoir tank. He said that was allowing air into the coolant system. That was fixed. Drove it for a day, and another leak develops at another hose that feeds the heater core. That was fixed. No heater or leak issues.
So now at highway speeds, 70+, my temp gauge will spike to up to 238 degrees, then back to normal within 10 seconds. I took it back in and he bleed some air out but it is still happening. He said this is normal for this engine. As long as it below 240, it is ok? Is it? Has this been happening before and I just didn't notice? I asked if the thermostat should be replaced and he said no.
BTW,,,, I called my local dealer and said they were 2 weeks out to look at it!
Thoughts?

I’d bet you still have a small leak, which allows coolant to escape and air to be drawn into the system when the engine and coolant cools down.

The high engine temperature on the highway indicates air in the system. If the radiator cooling fans were not operating properly, there would still be enough air forced through the a/c condenser and radiator to cool the coolant.

After several engine heat-cool cycles, check your coolant reservoir. Is the level dropping? Perhaps mark the current cold coolant level with a piece of painter’s tape, and then check it each day after it cools down.

 

[wakeboarder]

Mine has never been over 220° either even while towing. I changed my thermostat proactively since I had the old style. It now averages 10°F cooler than before I replaced the thermostat. I replaced it with the stock part number.

 

[SyndicateZ]

I have a 2019 Platinum, with 89k. I was having interior heater issues. Heat would be intermittent. My local mechanic found a tiny leak in near my reservoir tank. He said that was allowing air into the coolant system. That was fixed. Drove it for a day, and another leak develops at another hose that feeds the heater core. That was fixed. No heater or leak issues.
So now at highway speeds, 70+, my temp gauge will spike to up to 238 degrees, then back to normal within 10 seconds. I took it back in and he bleed some air out but it is still happening. He said this is normal for this engine. As long as it below 240, it is ok? Is it? Has this been happening before and I just didn't notice? I asked if the thermostat should be replaced and he said no.
BTW,,,, I called my local dealer and said they were 2 weeks out to look at it!
Thoughts?

I also have a 19. This is a dumb question, how are you able to see the exact temp the engine is at? The temp on my cluster just shows the blue bar but no digits..

 

[DavidCola]

Mine is the same. When the temp hits 228+, it actually shows the number. This is why I am perplexed. The mechanic says this is normal but how have I not noticed in the prior 89k of miles??

 

[DavidCola]

I’d bet you still have a small leak, which allows coolant to escape and air to be drawn into the system when the engine and coolant cools down.

The high engine temperature on the highway indicates air in the system. If the radiator cooling fans were not operating properly, there would still be enough air forced through the a/c condenser and radiator to cool the coolant.

After several engine heat-cool cycles, check your coolant reservoir. Is the level dropping? Perhaps mark the current cold coolant level with a piece of painter’s tape, and then check it each day after it cools down.

Thanks. That makes sense. I was told that a pressure test was done. IDK.

 

[99WhiteC5Coupe]

Thanks. That makes sense. I was told that a pressure test was done. IDK.

On my 2015 Expedition, purchased new, the water pump was replaced at about 70,*** miles. It had a slow leak, which wasn’t apparent. The dealer declared it had no leaks after a pressure test (despite a dropping coolant level)

I returned and insisted it be inspected on a lift. The mechanic quickly saw signs of a coolant leak from the water pump. It apparently was only leaking while being driven, and did not drop any coolant on the ground while parked.

 

[scottdm]

I also have a 19. This is a dumb question, how are you able to see the exact temp the engine is at? The temp on my cluster just shows the blue bar but no digits..

Not a dumb question. Forscan allows you to change settings to allow the instrument cluster to display the values for the engine temp, transmission temp, etc. Check out the Forscan section on this forum if you're interested in trying it out. It's a free license and there is a spreadsheet that provides common modifications that users have validated.

 

[scottdm]

Mine has never been over 220° either even while towing. I changed my thermostat proactively since I had the old style. It now averages 10°F cooler than before I replaced the thermostat. I replaced it with the stock part number.

Mine has also never been over 220 F. I had wildly fluctuating temps displayed recently and had the thermostat replaced, and temp now consistently runs 185-190F in normal driving after engine is at operating temp.

 

[wakeboarder]

I also have a 19. This is a dumb question, how are you able to see the exact temp the engine is at? The temp on my cluster just shows the blue bar but no digits..

Forscan may be used to make the change.

 

[keny01998]

For a long trip over 10 hours, I usually got engine temp over 230 for 1 minute or 2, sometimes it went up to 235 but went away. My trans temp went up to 217-220.

 

[2020ExpyPlatinum]

I would guess there is air trapped in the system possibly. Some vehicles have a very specific bleed procedure to get the air out.

If it is not air in the system is it possible the automatic louvers are acting up behind the front grill? I know on our expedition it has computer controlled louvers that open or close depending on the vehicle temperature.

 

[byathread]

My 2019 will, at certain points, show the coolant temp when it reaches that threshold, usually noticed it after heat soaking events like max throttle while towing or driving the piss out of it (hard acceleration uphill on the highway, etc.). It shows upwards of 238 or so and then recedes, basically due to the thermostat opening lag and coolant flows, is what I always thought... Normal, no leaks I'm aware of and has been doing that since new. Currently at about 46K... Even at 240-242 briefly, it's probably fine/not cooking it/within tolerance. I remember seeing 238 or 240 once and the gauge turned amber then went right back to blue. Unless there is clear evidence of a leak, then, just drive it is my $0.02...

 

[Artie]

Reading through this thread I’m wondering if not purging the cooking system could have caused my transmission temperature spike. Does anyone know if the transmission has its own completely separate cooler or does it share with the radiator?

 

[wakeboarder]

Reading through this thread I’m wondering if not purging the cooking system could have caused my transmission temperature spike. Does anyone know if the transmission has its own completely separate cooler or does it share with the radiator?

It uses coolant from the engine’s radiator. There is a heat exchanger under the transmission.

 

[Soliyou]

These engines can be difficult to bleed properly. A trapped air bubble may cause a spike in temperature and high pressure that can lead to leaks.

The shop manual only recommends using the vacuum fill procedure for the coolant.

The old style thermostat is also known to fail and cause slight overheat after coolant change.

 

[wakeboarder]

These engines can be difficult to bleed properly. A trapped air bubble may cause a spike in temperature and high pressure that can lead to leaks.

The shop manual only recommends using the vacuum fill procedure for the coolant.

The old style thermostat is also known to fail and cause slight overheat after coolant change.

My shop manual has both vacuum fill and without a vacuum fill. I followed the manual with the front uphill and on ramps. I also squeezed the coolant hoses. I have towed since then and haven’t seen any bleed issue. If I remember correctly, the bleed procedure takes 1/2 hour to 45 minutes.

 

[Soliyou]

My shop manual has both vacuum fill and without a vacuum fill. I followed the manual with the front uphill and on ramps. I also squeezed the coolant hoses. I have towed since then and haven’t seen any bleed issue. If I remember correctly, the bleed procedure takes 1/2 hour to 45 minutes.

Honestly I didn’t see the other procedure in the manual, but the manual is huge!

I am referring to the flush instructions shown below:

 

[3rd Expyowner123]

My 2018, at about 70k miles began showing temperatures above the temperature gauge about a year ago when driving 85 mph on the freeway or pulling our boat at about 70 mph. (beginning to over heat). This is not a normal condition. (Mechanic at my Ford dealer agreed).
For my truck, the fix was replacing the thermostat. I spoke with two different Ford advisors at two different dealers who both stated that thermostats do not commonly get replaced. I paid for the repair (approx $320) and have not had any temperature indication above the gauge since.
In terms of repair history, earlier my truck had weep dripping from the water pump and water pumped was replaced under my Ford extended warranty. Moral of the story, replace thermostat whenever changing water pump.
As I type my truck is having heater hoses replaced, as one began with a slow leak. This repair is not included under my extended warranty.
In November dealer replaced the cam phasers under warranty. I have seen other threads here regarding heater hose connector leaks after cam phasers work. Although I do not know if the two are related.