2021 Ford Bronco Sport Thumping/Flapping noise

[Johnny]

Ever since I purchased my Bronco Sport new, I have experienced an annoying flapping/thumping noise coming from the rear cargo area both left and right side. The noise presents itself when traveling over 40 mph. It was hard to pinpoint the source as I believed it was coming from underneath the vehicle. With it not making any noise below 40 mph, I thought it had to do with something that was flapping caused by wind speed. I focused under chassis covers that are mounted below the fuel tank and extending to the rear fender outer wheel wells. Noting I did would eliminate the problem. Finally, I crawled into the cargo area while someone else drove the vehicle over 40 mph. I located the source of the noise coming from the cargo area left and right trim panels. There are two molded in vents on each side where I could hear the noise coming from. Behind these panels are what is referred to as the "rear Air extractors". These are basically plastic vents with rubber flaps that allow air to exit the vehicle cabin for air circulation. I removed the inner trim panels and a lower exterior trim panel to expose an opening large enough to fit my hand between to access the air extractor. I then pulled on the flaps to tear them away from the vent. There are 3 per each side. They are made of very thin, .018', flexible rubber. What was happening was that air moving over and in between the outer fender wells caused these rubber pieces to flap resulting in this constant thumping/ flapping noise. I put the trim panel back in place and test drove the vehicle, and problem was solved. No more thumping/flapping over 40 mph. In my opinion, this is clearly a design defect caused by using a method to make the function of venting cabin pressure the cheapest way possible with clearly no testing. This should have been caught during design testing. There are so many cheap shortcuts Ford has made to lower their cost and not provide a proper function that I won't go into further in this thread. Regarding the function now of these air extractors without the rubber flaps; it will make no difference without the flaps because the vents are covered behind insulation, so they were nonfunctional anyway. hope this help anyone else struggling with this problem. There are plenty of videos out there that show how to remove the inner trim panels.

 

[Dude]

… Behind these panels are what is referred to as the "rear Air extractors" and

Fyi.. here is what Ford has to say:

SSM 51874 2021-2023 Bronco Sport, 2020-2023 Escape - Rattle Or Flapping Noise From The Rear Air Extractors

Some 2021-2023 Bronco Sport and 2020-2023 Escape vehicles may exhibit a rattle or flapping noise coming from the rear air extractors while driving. This may be due to the normal operation of the rear air extractors. To determine if this is a normal condition, perform a road test at 40 mph (65 km/h) or above. Inspect if the noise is coming from the rear extractors. During the road test alternate air conditioning (A/C) between fresh mode and air re-circulation mode. If the noise is eliminated when the A/C is in fresh mode, this is considered a normal characteristic of the vehicle and no repairs should be performed.

 

[Meanderthal]

There are engineers in almost every sizable company who focus on cost reduction. Even before a product is introduced on the market, there are already people working on ways to make it less expensive.

I realize that this has been frustrating for you but to assume this part was introduced without testing it is purely an emotional response. The cost of a recall of any kind far outweighs the testing needed to prove the function. That is not to say that the testing always exposes every possible way that a part could fail, or just be annoying in this case. Again there are people who spend their entire careers just thinking about how something could fail and designing tests to mitigate those failures.

Apparently there are times/examples of this part making noise. It is not very widespread or there would be more evidence of it here on the forum. I seem to remember some talk about noises from the cargo area but nothing that has been brought up consistently. Maybe it is just something to do with the parts on your BS?

 

[KidWiff]

mine does this to some extent but nothing i would call thumping.. it just lets me know it's there and not performing to expectations. Still, it gets a little annoying to think a simple vent can't get done without an issue. If it gets unbearable, i'll pull it. Until then, i might try my wife's surefire odd-noise abatement method and turn the radio up a little higher

If/when i DO pull those vent flaps, i'll need to start worrying about how much faster my BS will fill with water should i end up in a , pond, lake, or perhaps the ocean.

 

[Johnny]

Fyi.. here is what Ford has to say:

SSM 51874 2021-2023 Bronco Sport, 2020-2023 Escape - Rattle Or Flapping Noise From The Rear Air Extractors

Some 2021-2023 Bronco Sport and 2020-2023 Escape vehicles may exhibit a rattle or flapping noise coming from the rear air extractors while driving. This may be due to the normal operation of the rear air extractors. To determine if this is a normal condition, perform a road test at 40 mph (65 km/h) or above. Inspect if the noise is coming from the rear extractors. During the road test alternate air conditioning (A/C) between fresh mode and air re-circulation mode. If the noise is eliminated when the A/C is in fresh mode, this is considered a normal characteristic of the vehicle and no repairs should be performed.

 

[Johnny]

Thanks for the official Ford technical bulletin answer. This is the point I was trying to make. Ford knew this was a problem and they consider this flapping noise normal operation. It is totally unacceptable that a company makes a statement like this; normal and acceptable to experience a flapping noise. I appreciate everyone weighing in.

 

[Johnny]

There are engineers in almost every sizable company who focus on cost reduction. Even before a product is introduced on the market, there are already people working on ways to make it less expensive.

I realize that this has been frustrating for you but to assume this part was introduced without testing it is purely an emotional response. The cost of a recall of any kind far outweighs the testing needed to prove the function. That is not to say that the testing always exposes every possible way that a part could fail, or just be annoying in this case. Again there are people who spend their entire careers just thinking about how something could fail and designing tests to mitigate those failures.

Apparently there are times/examples of this part making noise. It is not very widespread or there would be more evidence of it here on the forum. I seem to remember some talk about noises from the cargo area but nothing that has been brought up consistently. Maybe it is just something to do with the parts on your BS?

Ford has probably corrected this problem with later models I would hope. Maybe this is the reason it's not showing up on this forum. The design fix and running change would be fairly simple. My BS was an early production year model, 2021.

 

[RS1]

I too have heard that type of noise. After crawling under and finding everything secure, I use the radio volume knob to fix the problem. Now glad to find out it is just an annoyance. I like my cheap fix.

 

[rootdoc]

This is an A/C vent issue with Ford Expeditions, also. The Expedition problem is random occurrence, not above 40mph. My wife recently noticed it in her 2012 Expedition. Switching A/C off and on stopped the clicking/thumping.

 

[Johnny]

I too have heard that type of noise. After crawling under and finding everything secure, I use the radio volume knob to fix the problem. Now glad to find out it is just an annoyance. I like my cheap fix.

Cheap car, cheap fix.

 

[jhnvan]

My bs does that same thumping (like heavy bass some times) sound and is so loud. I'll be removing those pieces to get rid of the noise.

 

[DLakeBadlands]

I had the same issue and found it to be the foam inserts around the spare tire was causing it. Used a cloth under the inserts sound gone.

I would be cautious removing the flaps as they are there to prevent critters getting into your car when its not moving.

 

[Johnny]

mine does this to some extent but nothing i would call thumping.. it just lets me know it's there and not performing to expectations. Still, it gets a little annoying to think a simple vent can't get done without an issue. If it gets unbearable, i'll pull it. Until then, i might try my wife's surefire odd-noise abatement method and turn the radio up a little higher

If/when i DO pull those vent flaps, i'll need to start worrying about how much faster my BS will fill with water should i end up in a , pond, lake, or perhaps the ocean.

Based on the design of these floppy flaps, there is no way dust or water is being kept out by them.

 

[Johnny]

I had the same issue and found it to be the foam inserts around the spare tire was causing it. Used a cloth under the inserts sound gone.

I would be cautious removing the flaps as they are there to prevent critters getting into your car when its not moving.

I also focused on the cheap styro foam trays. I isolated them with rags, etc. like you mentioned, but it did not fix the problem until I discovered the air extractors.

 

[Glamdring70]

I'm a little surprised you're so heavily focused on the noise from the cabin pressure flaps, considering your diagnosis method was to go throughout the vehicle and prevent dozens of other noises from interfering with the discovery of the flap noise. When I first got the car, I couldn't stand the clicking from the faulty park release cable. After two years of ownership, the car has an entire symphony orchestra going so the cable noise is greatly lessened. It's like when you hang a new picture in a room. You can't not notice it. Then eventually, you'll forget to dust it off. You may or may not have eventually become used to the sounds too.

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