Radiator leak / coolant disappearing

I think it goes like this:
Coolant was legit low and auxiliary fan turned on, which was my indication.
I put coolant in so that it was between the min and max lines as seen in the overflow reservoir.
Coolant went out such that it was below the min level.
I re-filled so it’s between min and max lines again.
Again coolant went out such that it fell below the min line.
I think the excess coolant after both refills went out both times through the overflow hose until it “had what it needed” (even though it appears low).
Fan has not turned on again.
So if the fan doesn't turn on then I’m fine with coolant being below the min line.
I may stop at a Ford dealership and ask to pop some hoods and see what others look like.

I had the same issue and had it fixed under warranty a couple months back in my '18. Dealer replaced a bunch of parts. From what I remember they replaced water pump & gaskets, cooling/radiator hoses, thermostat housing, and probably some other stuff that I can't remember. Haven't had any coolant issues since.

Thanks for the info. Do you happen to know the mileage. I'll have to see if I'm still under warranty.

I had a similar issue twice on my 5.4L. Once was because the (plastic!) coolant crossover gasket was broken and leaking coolant into the engine block valley, under the intake.

The other time was a bad radiator cap that would leak a decent amount of coolant under hard acceleration when the engine was hot. New cap fixed the issue.

I know it's a different engine but the cause could be similar.

Mysterious coolant leak. Look under your oil fill cap. a little creamy substance is normal if you don't drive much, but that forms over a few thousand miles. If you have quite a bit in a short time that can mean coolant in the oil. That could mean a head gasket or cracked head. This is an extreme case. Search for source first. If it is leaking near something hot it could be evaporating before dripping.

I am having identical symptoms with my 18 Expedition MAX Platinum with 52k miles. I haven't gotten under it yet to see where it's leaking, but I'm losing some each time I drive. My car has had an alarming number of problems and has lived at the dealership. Had the 10A transmission replaced (warranty thank God) about 10k miles ago due to complete failure. A/C problems (evap leaking in the rear? dealer still troubleshooting), electrical problems, had the crazy mirrors and seat memory position problem (fixed with a reprogram), rear defroster failure, buggy electronics interface, etc. Recently I was driving and the phone was ringing in the car and kept ringing no matter what I did. I even shutoff my phone. Car was still ringing... had to stop the car along the road and restart! Random error codes one day saying "See Manual" "Pre Collision Assist not Available" - ran in limp mode the rest of the way home... cleared on its own after a restart?? Rear Parking brake failure, sunroof guide rail broken wouldn't close, rear defroster broke, etc. All with under 55k miles! Ughh sorry to rant but I'm just so disappointed in the car overall. I want to love it - but we're beginning to hate it!

Sorry you've had bad experiences. Overall, I really like my '18 Exp Limited. I'd buy another one. As for my original post on the coolant leak...my coolant goes somewhere. When I got the oil changed a few months ago, I asked them to look for the milkiness and they said the oil was normal looking. So I put coolant in to raise it to the MAX line and in about 8 weeks it will reach the MIN line and I'll add coolant to raise it back to the MAX line and I'm fine with doing that.

DavidC said:

Sorry you've had bad experiences. Overall, I really like my '18 Exp Limited. I'd buy another one. As for my original post on the coolant leak...my coolant goes somewhere. When I got the oil changed a few months ago, I asked them to look for the milkiness and they said the oil was normal looking. So I put coolant in to raise it to the MAX line and in about 8 weeks it will reach the MIN line and I'll add coolant to raise it back to the MAX line and I'm fine with doing that.

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Yeah thanks - as an engineer I know that it's not as simple as just saying it's a "lemon" - there is a root cause for each failure. So far it's all been programming/software and faulty components and/or design issues. My favorite was hitting the memory seat preset and having the mirrors start going in and out endlessly like they are in panic mode, and then ratcheting/clicking endlessly??! haha Like... ... really??? There are many posts here about that one and sure enough a reflash of the DDM/PDM (there's a TSB I forget what it is now) fixed that. I'm a lifelong Ford fan and I have a Mustang with a Coyote that I built, but between my Flex, and my last expedition, and this one... man... Come. On. Ford.

Well, there are other girls in town. I bought mine, since at the time, it was the most technologically advanced full-sized SUV available. None of the other automakers had refreshed or redesigned their large SUVs. Though I said, I'd buy another one, and I would, I would start my research over again since Chevy has since re-designed the Tahoe/Suburban/Yukon and by now one of those, or some other SUV, may be better than today's Exp.

coyote-dogfish said:

Yeah thanks - as an engineer I know that it's not as simple as just saying it's a "lemon" - there is a root cause for each failure. So far it's all been programming/software and faulty components and/or design issues. My favorite was hitting the memory seat preset and having the mirrors start going in and out endlessly like they are in panic mode, and then ratcheting/clicking endlessly??! haha Like... ... really??? There are many posts here about that one and sure enough a reflash of the DDM/PDM (there's a TSB I forget what it is now) fixed that. I'm a lifelong Ford fan and I have a Mustang with a Coyote that I built, but between my Flex, and my last expedition, and this one... man... Come. On. Ford.

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Unfortunately, this is what happens when companies try to manufacture very complex things as cheaply as possible on a global scale. Just look at the Boeing 787 debacle.