Help! Overheating on a Road Trip :/

[madrose124]

We’ve read through other threads here but need help for our specific issue. We bought our max 4x2 3 months ago with 96k miles. Recently noticed the AC would randomly blow warm air for short periods of time maybe three different times but didn’t think to look at the coolant/trans temp gauge thinking it was an AC issue or de-icing cycling.

Thursday we came on a 900 mile roadtrip to visit my brother and on the way temps started rising and we got a warning. Not towing. Pulled over to stop and temps went right down. We ended up having to stick to about 60mph to keep coolant temps below 245ish. Hills would make it go up. Transmission temp would read 200-220+. We read about the sticking thermostat so we grabbed one from dealer and my husband replaced it even though he pulled the old one out and it was the same part (black tip). He also cleaned radiator as it was dirty and mud daubers had apparently tried setting up shop, presumably before we purchased it.

Appeared to fix the issue for about 25 minutes, however now it’s increasing tempature even at low speeds which before as soon as we would drive 40mph it would go below 230 (coolant temp). Especially if we stopped. There also seemed to be a 20-30 degree disparity between coolant temp and trans temp although both would rise. Now there’s about a 10 degree difference which means the transmission is running hotter. Changing the thermostat did not do what everyone else reported it would do (drop temps down to below 205).

My husband suspects now it may be the water pump.

However we need to leave Monday, it’s now end of day Saturday. My husband is going to track down parts, fortunately he is mechanically handy but we are without his tools, time and hate that this is happening 900 miles from home.

Would love any and all suggestions of things to check. No apparent leaks in the system. They did burp to check for air bubbles this morning. Coolant levels between min and max line.

 

[19ExpMaxPlatYYC]

I watch my transmission pretty close because I've had problems with it resulting in a rebuild. It runs in the 99 to 100 deg C in normal states.

While towing a 20 ft relatively lightweight boat (not a big heavy style but not a tinnie) it will run 100-101 deg C at lower speeds under 110 kph. If I push it at all to make a pass it rises to 104 deg C and I have to be very gentle to get it down to 101 and under.

Just a reference point for you.

 

[madrose124]

I watch my transmission pretty close because I've had problems with it resulting in a rebuild. It runs in the 99 to 100 deg C in normal states.

While towing a 20 ft relatively lightweight boat (not a big heavy style but not a tinnie) it will run 100-101 deg C at lower speeds under 110 kph. If I push it at all to make a pass it rises to 104 deg C and I have to be very gentle to get it down to 101 and under.

Just a reference point for you.

Thank you. We thought we had it fixed with a new water pump, however the only one we could get on the weekend was an autozone one. The original water pump had deteriorated seals on the gasket however this autozone one doesn’t have the same capacity as the OEM so we are experiencing little difference, although slightly improved. We aren’t towing anything and getting temps higher than that unless we go 60mph

 

[madrose124]

We are headed home now after replacing the thermostat (OEM) and the water pump (autozone brand, duralast brand I believe). The AZ water pump says it’s 53 gallons per minute vs the OEM 55 gal {apparently this is from an older ford forum so not sure if this still applies}so although we now have a new gasket with busted seals, I’m not sure it’s cutting it. We are still experiencing higher temps if we go over 60 mph.

The strange thing however is that when we left in the morning and ambient temps were cooler, we had no issue. After about 4 hours and ambient temps are now 100-110 *F, it’s back to higher temps where we have to go slower, especially on grades.

My husband thinks we need a new upgraded and larger radiator. I want to know why our car can’t handle the heat without the upgrade. Something doesn’t seem right to me.

If you happen to see a blue expedition max driving at 60mph along I 20 through Texas today, honk and wave.

 

[SyndicateZ]

We are headed home now after replacing the thermostat (OEM) and the water pump (autozone brand, duralast brand I believe). The AZ water pump says it’s 53 gallons per minute vs the OEM 55 gal, so although we now have a new gasket with busted seals, I’m not sure it’s cutting it. We are still experiencing higher temps if we go over 60 mph.

The strange thing however is that when we left in the morning and ambient temps were cooler, we had no issue. After about 4 hours and ambient temps are now 100-110 *F, it’s back to higher temps where we have to go slower, especially on grades.

My husband thinks we need a new upgraded and larger radiator. I want to know why our car can’t handle the heat without the upgrade. Something doesn’t seem right to me.

If you happen to see a blue expedition max driving at 60mph along I 20 through Texas today, honk and wave.

 

[Jozef Zoldos]

I had a similar problem and I posted a thread on this recently (https://www.expeditionforum.com/threads/2020-expy-overheating-at-highway-speeds.55007/). The original thermostat part number for the 2020 Expy is HL3Z-8575-AA and apparently, this part has problems with sticking resulting in overheating temps. Ford has upgraded the thermostat and new part number was HL3Z-8575-B. I am wondering if you put in the original "faulty" part and are unlucky enough to have sticking in both thermostats. When I changed to the upgraded thermostat, my issue was resolved immediately.

Hope this helps.

 

[madrose124]

I had a similar problem and I posted a thread on this recently (https://www.expeditionforum.com/threads/2020-expy-overheating-at-highway-speeds.55007/). The original thermostat part number for the 2020 Expy is HL3Z-8575-AA and apparently, this part has problems with sticking resulting in overheating temps. Ford has upgraded the thermostat and new part number was HL3Z-8575-B. I am wondering if you put in the original "faulty" part and are unlucky enough to have sticking in both thermostats. When I changed to the upgraded thermostat, my issue was resolved immediately.

Hope this helps.

Thanks to your thread we knew to get the 8575-B, which we did purchase and was already in the vehicle. I’m curious if we should replace the housing as well? It’s possible we got a defective thermostat but hard to say unless we get another. Both have the black plastic piece.

 

[mobile314]

I had a similar problem and I posted a thread on this recently (https://www.expeditionforum.com/threads/2020-expy-overheating-at-highway-speeds.55007/). The original thermostat part number for the 2020 Expy is HL3Z-8575-AA and apparently, this part has problems with sticking resulting in overheating temps. Ford has upgraded the thermostat and new part number was HL3Z-8575-B. I am wondering if you put in the original "faulty" part and are unlucky enough to have sticking in both thermostats. When I changed to the upgraded thermostat, my issue was resolved immediately.

Hope this helps.

We also had a same issue with coolant temps that came about on a road trip, could only go 60mph before it would overheat and we were not towing anything. We ended up changing out the thermostat with the updated OEM version one purchased from RockAuto and it solved the issue immediately. Seems like you guys already tried replacing the thermostat, surprised this did not solve it. Larger radiator...hmm you know what they stay/rule of thumb. Start with simple before diving into complex issues. After rereading your threads, I cant say that I can offer any other ideas. We are dealing with a new issue that I am trying to figure out where the rear ac blows warm, up front is cold and if I try to push heat through the back, no air comes out.

I know what I wanted to ask, how do you know how many GPM your water pump is pumping?

Hope you got home safe!

 

[madrose124]

We also had a same issue with coolant temps that came about on a road trip, could only go 60mph before it would overheat and we were not towing anything. We ended up changing out the thermostat with the updated OEM version one purchased from RockAuto and it solved the issue immediately. Seems like you guys already tried replacing the thermostat, surprised this did not solve it. Larger radiator...hmm you know what they stay/rule of thumb. Start with simple before diving into complex issues. After rereading your threads, I cant say that I can offer any other ideas. We are dealing with a new issue that I am trying to figure out where the rear ac blows warm, up front is cold and if I try to push heat through the back, no air comes out.

I know what I wanted to ask, how do you know how many GPM your water pump is pumping?

Hope you got home safe!

Thanks! I am also surprised am not above trying another thermostat on the chance the replacement we got was no good. As for the water pump, my husband said he realized the info he found was for older fords so I suppose we don’t know GPM on either pump now, so it’s possible they are all the same. We are having difficulty finding anything out stat wise. I’m really frustrated that the thermostat wasn’t the magic fix we were hoping for.

A few more hours to go till home.

 

[Soliyou]

There was a case of overheating couple of years ago and turned out to be bad radiator.

Other things to check first are the grille shutters (stuck closed) or faulty radiator fan.