Coolant loss

[Mosey]

When I picked up my new-to-me 2021 PB the main coolant reservoir level was at the minimum line. Since then I added some motorcraft 50/50 yellow coolant to bring the level up to max. After about three weeks the level has dropped about 1/2 between min and max. I have not observed leakage under the truck and and I have inspected the underside of the engine / radiator for any signs of leakage. Oil is perfect.

Could this changing level simply be the result of expansion/contraction?

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[ryanc111]

I hate to be the bearer of potential bad news but check out this thread for others (including myself) with a similar issue:
https://www.f150gen14.com/forum/thr...-exhaust-heat-exchanger-leak-megathread.8634/

 

[Gros Ventre]

That thread appears to apply to 2022 model year.

 

[ryanc111]

I have a 2021 and am having the same issue.

**Edit to add that mine is still drivable while waiting for the part (keeping an eye on the coolant levels) so not sure how, or if, that differs between model years.

 

[Gros Ventre]

K, having read and followed that thread for anything that might apply to my 21 PB, I found no entries on 21s. My take on it is either there is a temperature sensitive crack that opens or closes with temperature and/or there is a leak in the exhaust side such that leaking coolant goes out the exhaust pipe... Seen no evidence of this with my PB 21

 

[psambrose]

K, having read and followed that thread for anything that might apply to my 21 PB, I found no entries on 21s. My take on it is either there is a temperature sensitive crack that opens or closes with temperature and/or there is a leak in the exhaust side such that leaking coolant goes out the exhaust pipe... Seen no evidence of this with my PB 21

The parts referred to in that thread are exactly the same on the 2021 and 2022 models. Both years can experience the same leak.

 

[Gros Ventre]

Just because they're exactly the same part doesn't mean they were made by the same firm. I saw no evidence in the series of posts that indicated the 21s had that problem. Even if they were made by the same firm, there could be differences in the manufacturing techniques leading to a propensity for leakage in one year and not the other...

 

[ThyDayWalker]

K, having read and followed that thread for anything that might apply to my 21 PB, I found no entries on 21s. My take on it is either there is a temperature sensitive crack that opens or closes with temperature and/or there is a leak in the exhaust side such that leaking coolant goes out the exhaust pipe... Seen no evidence of this with my PB 21

I've got a 2021 PB and... here's my coolant level 2 weeks apart. The thread is 100% relevant to all PBs, unfortunately. I am under the "can see the coolant level going down, but can't find the leak" (which is best case). The leaks can get worse / vehicle becomes undrivable. The main culprit is a heat exchanger unique to PBs that leaks, but... it could be anywhere! I've had it at the dealer multiple times to pressure test - nothing. No puddles even when vehicle sits for days... just fill it up every month.

Filled to top:

2 weeks later...

 

[Mosey]

Thanks for all of the replies. The missing coolant is from the main system, the large reservoir, not from the small tank associated with the hybrid cooling loops. From my reading, this would eliminate the exhaust heat exchanger as the culprit as it is used to warm the batteries.

 

[Gros Ventre]

Note that it is possible to have a leak that only opens up when hot. So next time you have the dealer run a leak test, require them to do it with the truck fully warmed up.

 

[ryanc111]

As a side note, I haven't seen any noticeable leaks on my truck. The faulty heat exchanger was diagnosed initially by a squeaking sound when the engine switches from electric to ICE and back. I did have a CEL for a bit but that has gone away.

In any case, I hope your issue isn't related to the heat exchanger!

 

[surveyor]

I've got a 2021 PB and... here's my coolant level 2 weeks apart. The thread is 100% relevant to all PBs, unfortunately. I am under the "can see the coolant level going down, but can't find the leak" (which is best case). The leaks can get worse / vehicle becomes undrivable. The main culprit is a heat exchanger unique to PBs that leaks, but... it could be anywhere! I've had it at the dealer multiple times to pressure test - nothing. No puddles even when vehicle sits for days... just fill it up every month.

Filled to top:

2 weeks later...

Did you ever find the cause?

 

[ThyDayWalker]

Did you ever find the cause?

Yep! It's the infamous Powerboost-only exhaust heat exchanger leak, which seems hundreds (or thousands!) of people are having. The dealership finally said there was Ford documentation (not sure if TSB, or whatnot) and fixed it.

 

[Snakebitten]

Thanks for all of the replies. The missing coolant is from the main system, the large reservoir, not from the small tank associated with the hybrid cooling loops. From my reading, this would eliminate the exhaust heat exchanger as the culprit as it is used to warm the batteries.

It's just the opposite.
The exhaust heat exchanger is part of the engine coolant loop, thus the larger expansion tank.

Not the Hybrid cooling loop with the smaller expansion tank.

 

[Gros Ventre]

I've had an odd color to my engine coolant. Given the exhaust heat exchanger leak I had Blackstone Labs analyze a sample. Despite the odd color, they came back and said no evidence of exhaust gasses in the coolant. The level is not decreasing but I remain suspicious something is going on... Keep in mind that there can be a leak that either opens up or closes down with temperature, so your leakage may not be apparent with the engine cold or hot. Try and track whether the leak is hot or cold and then when you go into the dealer require them to check for it in that vein.

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