During wintertime, our Fusion makes a 'sloshing' or 'waterfall' sound the first time you pull away on a cold start. The sound comes from the heater core and/or the center stack area (hard to pinpoint). It seems to only happen under 40 degrees F, and ONLY the first time you moderately accelerate after you start the car. If I were to stop, then take off again, the sound is not there. Evidently, a bunch of 2.5L Fusion owners have this issue. Ford have said that they acknowledge it, but say that it is not a reliability issue and not to worry. I believe a recommended fix was to use the coolant overflow tank from the 3.5L Fusion Sport, but in many cases the issue is still there. So, a few things...
1) Why does this only happen under 40 F, and only the first time I pull away from a stop?
2) In a self-purging system, why is that small amount of air in the system?
My only guess is that somehow when cold, the system pulls in a very small amount of air on a cold start, and then eventually purges it out once it has cycled through. If we have the heat on full blast (obviously not hot yet since the car is cold) at say 45 degrees, the sloshing sound is not there. It has to be closer to freezing out to notice this.
While other Fusion owners have this issue every time the heat is on, while accelerating every time, my issues seem very minimal. I'm just curious as to why it happens, then goes away and 'fixes' itself? Coolant tank is full, and always has been. Any ideas? Ford does have a purging procedure for this issue (or maybe 2 procedures), but none of them have worked beyond a few weeks because the issue always returns. Evidently, Ford are well aware of this also. FWIW, every Fusion ever built has used the exact same heater core, both 1st and 2nd generation Fusions. And every Fusion ever built has used the exact same coolant overflow tank, with the exception of the Fusion Sports. Yet the only Fusions to have this issue are the 2.5L 2nd gen (with the exception of a handful of Fusion Sports).
I should also add that our heat is always good and hot, and not intermittent. And the engine temp always sticks right in the middle of the temp gauge and never fluctuates. This is opposite of engines that have air in their system, so from that standpoint, all seems well.
1) Why does this only happen under 40 F, and only the first time I pull away from a stop?
2) In a self-purging system, why is that small amount of air in the system?
My only guess is that somehow when cold, the system pulls in a very small amount of air on a cold start, and then eventually purges it out once it has cycled through. If we have the heat on full blast (obviously not hot yet since the car is cold) at say 45 degrees, the sloshing sound is not there. It has to be closer to freezing out to notice this.
While other Fusion owners have this issue every time the heat is on, while accelerating every time, my issues seem very minimal. I'm just curious as to why it happens, then goes away and 'fixes' itself? Coolant tank is full, and always has been. Any ideas? Ford does have a purging procedure for this issue (or maybe 2 procedures), but none of them have worked beyond a few weeks because the issue always returns. Evidently, Ford are well aware of this also. FWIW, every Fusion ever built has used the exact same heater core, both 1st and 2nd generation Fusions. And every Fusion ever built has used the exact same coolant overflow tank, with the exception of the Fusion Sports. Yet the only Fusions to have this issue are the 2.5L 2nd gen (with the exception of a handful of Fusion Sports).
I should also add that our heat is always good and hot, and not intermittent. And the engine temp always sticks right in the middle of the temp gauge and never fluctuates. This is opposite of engines that have air in their system, so from that standpoint, all seems well.
