2019 Max overheating when towing

[spotdog14]

Boost increases with engine load. Using a numerically lower gear reduces load on the engine, so the turbochargers will not spin as hard. Basically, it is using the gearing to reduce load on the engine, which means less air is needed from the turbochargers.

This exactly. Using the transmission gearing to keep the turbos from spooling.

In my f150 I would regularly lock out 6 and 5th gears.

 

[duneslider]

Turbos spool via the exhaust gasses passing through them. So, higher RPM will cause them to spin faster and create more boost. Gear shouldn't matter so much as what the engine RPM is. I honestly haven't looked super close at the ecoboost engine but I suspect one spools at a lower RPM to bring on boost earlier and the other spools up at a higher rpm to keep the power coming. That would also explain the smooth power delivery it seems to have. Anyway, higher RPM will always create more heat and if you are running at a higher rpm and NOT moving fast enough to pass enough air across the radiators, coolers, etc then it will get hot.

I have not seem the coolant temp get hot on my expedition but the trans has gotten hotter than I would like when pulling a load and not moving fast (steep grade and under 15mph). Once I hit the dirt road and could put it in 4L the gear reduction made everything happy again and all temps went back to normal, even with the low speed.

 

[Deadman]

Lower gears simply are easier to do work in, so the engine works far less. Yes it turns more rpm, but its doing the work easier because of the mechanical advantage of the lower gears. Top gears works it the hardest obviously.

 

[JasonH]

Turbos spool via the exhaust gasses passing through them. So, higher RPM will cause them to spin faster and create more boost.

You forgot about throttle position. Other things being equal (grade, wind, etc.), big difference in air volume turning 4K RPM in 4th vs 4K RPM in 6th. You can flow less air at higher RPM, because the throttle will not be open as much. This is what happens when you downshift. RPM goes up, but load drops and the turbos are not driven as hard due to reduced airflow.

 

[Soliyou]

A youtube video of a 2017 Econoost owner with the same problem. Turned out to be a defective radiator:

 

[Artie]

A youtube video of a 2017 Econoost owner with the same problem. Turned out to be a defective radiator:

That video triggered my old panic response that I developed driving questionable cars in my 20-30’s lol. I hate the feeling of watching the gauges hoping to not breakdown. Blowing full heat in August, been there done that. We are about to purchase a trailer and I pray I don’t have any issues.

 

[Grey ghost]

I just got a 180 thermostat and a tuner upgrade from 5 star because the heat in florida gees intense may give me a margin if I tow.

 

[Deadman]

They run hot thermostats for Emissions, so dropping that might help a ton.

 

[ChristopherWatson]

2018 Expedition XLT MAX. Cruising for about 8 hours at 75-80 MPH towing 1500 lb trailer. Suddenly transmission downshifted to 5th/6th gear. Would not go into "overdrive" - 8, 9, 10.
Engine gauges showed normal temp - I didn't think to check transmission temp.

Does this mean the transmission fluid overheated. Limped home remaining 100 miles. Next day transmission seemed fine for local (non-high speed driving).

I'm thinking I should take it in and have the transmission fluid changed.

 

[Artie]

2018 Expedition XLT MAX. Cruising for about 8 hours at 75-80 MPH towing 1500 lb trailer. Suddenly transmission downshifted to 5th/6th gear. Would not go into "overdrive" - 8, 9, 10.
Engine gauges showed normal temp - I didn't think to check transmission temp.

Does this mean the transmission fluid overheated. Limped home remaining 100 miles. Next day transmission seemed fine for local (non-high speed driving).

I'm thinking I should take it in and have the transmission fluid changed.

I’d take it in if it were me, that’s a really light trailer.