aporias

Hey guys,

I own a brand new S3 2017 with 1500km. Sometimes when I switch off the car I can hear a "pumping" noise like a "heartbeat" from the rear right passenger side behind the gas cap. Once I open the gas tap I hear a hissing sound and the "pumping" noise stops.

I talked to the dealer and we have replaced a gas cap to test. I am pretty sure that is related to high ambient temperature (here is Greece) since it's not happening every time I drive and turn off the car.

Do you have any ideas? Is this happening to any of your A3s?

Thanks in advance.

Dimitris

Vancity88

I had the same noise in my Golf and S3, it happens when you open the driver's door when the car is parked for few hours. It basically pumps the fuel to engine before you start the car.It is normal and you don't need to be worry about it.

plat27265

+1. I used to own a 2011 VW GTI which is closely related to the A3/S3 models. Same knocking-type noise can be heard as you and Vancity88 just described above. Sometimes it happens within the few minutes of initially operating your car after it has been parked for a while. It is the fuel pump priming the fuel lines and getting the car ready for operation. This is normal. If one of my guest passengers ask me about it, I just say there's elves in the workshop making sure the car is in tip top shape 24/7.

Darryl Johnson

I had a similar noise from the gar cap of my MINI. According to BMW/MINI, this was just the pressure in the fuel tank being regulated. I have no idea why they would select a mechanism that would regulate the pressure in a series of "burps", but I am not an automobile engineer.

The hissing sound you hear when you remove the cap is the pressure adjusting all at once, instead of the sequence of small adjustments that produce the "burping" or "pumping" noises.

I haven't noticed it on the Audi, but it was quite noticeable on the MINI. And not only when I turned the car off. Idling at a red light, I could sometimes hear the noises.

In any case, I doubt you have anything to worry about.