Overheating Issue

[chops]

Towing our 6k pound camper west and on the tiniest inclines started seeing the coolant temp appear and go into the mid-upper 230s. Highest we saw was 237 as I was very diligent about managing the temps. We knew if these mole hills in SE VA are causing it, no way we'll get past the bigger hills out west so we turned around. Note that we also saw similar behavior this past summer in the mountains in PA when we weren't even towing - but those were much bigger inclines than what was causing it most recently.

We have a 2020 Expedition Max with HD tow package and 90k miles. This camper is large, but we've towed it before with this vehicle without issue. Transmission blew up this summer and was replaced and at no point during this brief trip did we see temps increase on the transmission, even while the coolant temps were hitting 235+. Wondering if that indicates an issue with the cylinder head temp sensor as described here: https://www.expeditionforum.com/threads/2020-expy-overheating-at-highway-speeds.55007/post-502671 ?

Took it to the local Ford dealership and of course they couldn't replicate the issue. They said the following: "found engine cooling system to operate normally performed key on engine running test on pcm did not retrieve any codes found no over temp codes in vehicle history. pressure tested system and found no leaks from cooling system. using a temp gun found all cooling hoses to be at the proper tempter test
drove and cooling system was still operating properly. could not verify the concern "

Could the testing they conducted still indicate a problem with the thermostat as discussed here: https://www.expeditionforum.com/threads/help-overheating-on-a-road-trip.56618/post-515331 ?

Any other ideas besides cylinder head temp sensor or thermostat would be appreciated.

 

[JasonH]

How many miles on the vehicle and which gears? Premium fuel?

 

[chops]

How many miles on the vehicle and which gears? Premium fuel?

90k miles, we were driving 55 and it was in 8th gear basically the whole way, sometimes 9th going downhill. Sitting at 2k rpm. Tank full of 93.

 

[JasonH]

90k miles, we were driving 55 and it was in 8th gear basically the whole way, sometimes 9th going downhill. Sitting at 2k rpm. Tank full of 93.

Try using a lower gear and getting RPM up a bit. The engine will generate a lot of boost to tow in an overdrive gear. More boost means more heat. If you're in a headwind, the engine could be spooling the turbos and you would not even know it's working very hard.

You can monitor boost using a Veepeak BLE+ and Torque app. It will also let you monitor other important data, like coolant and transmission temps, and tire pressure.

 

[chops]

Try using a lower gear and getting RPM up a bit. The engine will generate a lot of boost to tow in an overdrive gear. More boost means more heat. If you're in a headwind, the engine could be spooling the turbos and you would not even know it's working very hard.

You can monitor boost using a Veepeak BLE+ and Torque app. It will also let you monitor other important data, like coolant and transmission temps, and tire pressure.

Thanks Jason for that advice. I assume 8th is an OD gear then?

And does this sound like normal behavior given that previously we didn’t experience these high coolant temps when towing?

Cheers

 

[JasonH]

Thanks Jason for that advice. I assume 8th is an OD gear then?

And does this sound like normal behavior given that previously we didn’t experience these high coolant temps when towing?

Cheers

The 4th gen has a 10 speed. Gears 8, 9, and 10 are all overdrive gears. You can lock out the upper gears by pressing down on the gear selector repeatedly. I asked about the mileage because my engine ran hot when my water pump was failing. But that didn't happen until well beyond 100,000 miles. My water pump made an awful racket when it was on its way out. Perhaps check your coolant levels, as the coolant weeps from the pump when it's failing. It's possible the thermostat could also be failing, but I don't know of a straightforward way to test that. Premium fuel is also recommended when towing.

I mentioned the headwinds because even if the vehicle was working properly before, these vehicles have a towing frontal limitation and it's possible that a stiff headwind and top gear were just too much for it. My 3rd gen would tow my camper in 6th, but it used a lot of boost to do so. I think that contributed to my manifold warping.

The Veepeak BLE+ and Torque are invaluable when towing and for general vehicle maintenance.

 

[DieselMonk]

Also look for the updated thermostat and make sure you have it.

 

[Grrumpy]

Purchased a 2019 FX4 optioned with the HD tow and proper tow gearing. Had 112,000 miles on it but in excellent cond, with all records. I did notice that it ran hot both coolant and trans....have a Scan Gauge lll to monitor. Since we tow a 7000 lb travel trailer, having 230 coolant and trans fluid temps is unacceptable.
Took it to local dealer where I bought it and had them do a coolant flush and a new 190 degree thermostat.
After picking it up, noticed temps were drastically lower....solo coolant under 195 and trans under 190.
Just got back from a 2000 miler 2 week on the road to Maine and surronding areas. Towing our Jayco all over Maine, Vt, New Hamp, never had any overheating problems. Coolant kicked up occasionally to 217 where fan kicked on, and trans fluid never once got over 215.....and that was running thru the White Mountains.
Bottom line.....get your coolant and thermostat taken care of.......just a simple $15 buck part can go bad causing all kind of problems.

 

[chops]

Purchased a 2019 FX4 optioned with the HD tow and proper tow gearing. Had 112,000 miles on it but in excellent cond, with all records. I did notice that it ran hot both coolant and trans....have a Scan Gauge lll to monitor. Since we tow a 7000 lb travel trailer, having 230 coolant and trans fluid temps is unacceptable.
Took it to local dealer where I bought it and had them do a coolant flush and a new 190 degree thermostat.
After picking it up, noticed temps were drastically lower....solo coolant under 195 and trans under 190.
Just got back from a 2000 miler 2 week on the road to Maine and surronding areas. Towing our Jayco all over Maine, Vt, New Hamp, never had any overheating problems. Coolant kicked up occasionally to 217 where fan kicked on, and trans fluid never once got over 215.....and that was running thru the White Mountains.
Bottom line.....get your coolant and thermostat taken care of.......just a simple $15 buck part can go bad causing all kind of problems.

Man that’s exactly what I’m hoping for. Will do the new thermostat and coolant flush and I’ll report back.

 

[LG_123]

I also tow an 8,000 lb trailer and I nearly always have gears 8-10 locked out. I also frequently force a downshift to keep the RPMs a bit higher.

Fuel economy remains the same and the engine runs significantly less hot when it’s using less boost. I keep the boost gauge on the dash most of the time when towing and optimize driving and gear selection for lower boost.