Ford Fiesta ST Forum banner

Helicopter noise and vibration at speeds over 50 mph

12K views 13 replies 9 participants last post by  Anticyclone 
#1 ·
I just bought a 2014 Fiesta less than 48 hours ago. Today when driving with my friend on the highway at about 50 mph the car started to make a wind helicopter sound and you could actually feel the air pressure and vibration inside the car for several miles. We had the air conditioning on. The noise/vibration was worse when the front windows were up. It was intense enough that it scared us and we pulled off the highway and inspected the tires, nothing looked amiss. We rolled the windows down for the ride back to the Ford dealer and took the salesman for a drive and of course the car did not do it again. Any ideas on this? I am thinking I should return the car as I have to believe it will happen again. I am not sure if it is the aerodynamics, seals, or the wheels.
 
#2 · (Edited)
Sunroof / Rear windows ?? Sounds like wind Buffeting



 
#3 ·
The car does not have a sunroof. I may have had the back windows partially down when it started. I noticed immediately that the sound and whirling pressure vibration was affected by windows being opened or closed so I tried different positions to see if I could get it to stop and start again. With all the windows closed it did it, and when I opened one or more windows it stopped. I drive that highway all the time, often with a strong crosswind, and I have never experienced that before in any car. There was no cross wind yesterday, only the wind generated by the forward movement of the Fiesta. The air outside was still with no movement in the trees. The road surface we were on was smooth and in good shape. The steering and handling was unaffected. I have to say that the sound and pressure vibration was intense enough to be very distracting and alarmed my friend who doesn't over react. I am going to take it back to the Ford dealer today and see if the mechanics can find anything. I will ask to exchange the car as I think it is something that could happen again and may have something to do with the way it was put together on the assembly line. The salesman yesterday said he had never heard of such a thing.
 
#4 ·
I think I may know what is happening.

They don't make cars the way they used to. I remember when you could drive with the driver's window open, and be fine. But lately, on newer cars, at least with my 2008 VW R32, open the window and wind comes blowing in and at you from left behind side. And for some reason, when the A/C is turned on, no matter what, it appears to be in the recycle mode (on cars with auto climate control)- meaning it is using cabin air, not from the outside. So in essence, it is also pulling the outside air in through the window (inside is now a "low pressure area" and the outside is the "high pressure area"). This can cause a buffeting effect, your pressurized helicopter effect.

I have found opening the driver's side rear door glass helps to stop this, or turning off the A/C to stop the recirculation by now having some higher cabin pressure to keep the outside wind, out.
 
#5 ·
Thanks for the replies. The Ford Service Dept. said they could find nothing wrong with the car. Off the record the man in the Ford service dept. office said similar things as ST Rocky about it being the aerodynamics of the model and that other small cars do it as well. He said keep the windows up and use the a.c. or keep at least two open. It may depend on the car models as to what exactly will work. If I could get my money back I would as I don't like having to worry about my window adjustments and a.c causing it again.
 
#10 ·
Page 73 in the owners manual (first printing) touches very very lightly on Pulsing with just one window down and it suggests you open a opposite window slightly.. not that this was the case but it appears they are aware of wind buffeting effect with one window down. Though they down address the HVAC issues some have seen. I have not had the need to run the AC yet as it is a lil chilly for that up nort here.. lol



 
#12 ·
The answer is simple physics mate.

Unequal (unstabilised) pressure = noise

Even if you had the windows up you were still causing air to suck into the cabin and buffet against the stabilsed air inside. Depending on your velocity, temperature of the air inside versus outside and other forces pushing or pulling the car, of course you'd get that noise. Same happens in some boats and motorbikes, and they don't even have an enclosed cabin! Why do you think race car drivers wear earplugs sometimes...
 
#13 ·
The answer is simple physics mate.

Unequal (unstabilised) pressure = noise

Why do you think race car drivers wear earplugs sometimes...
Because racecar ?? Just teasing :) you are correct but loud pipes save lives I'm told....
Land vehicle Vehicle Car Touring car racing Motorsport




 
This is an older thread, you may not receive a response, and could be reviving an old thread. Please consider creating a new thread.
Top