2006 Honda CRV, about a year ago we started to hear a popping sound like that of a metal can being squeezed or expanding underneath the vehicle (back-side) right after we turned the car off. It would only take a few seconds to sound off. We took it to the dealership recently and they stated that most likely it was coming out of the muffler or inside baffle as the metal contracted. They could not locate the area since it happens so fast. No issues with drive-ability or safety, just a minor occurrence. Has anyone experience this or have any other suggestions or ideas?
Most likely, if this noise begins a few seconds after you shut off the engine, and if the noise ceases after a few minutes, then the dealership is correct. As the various parts of the exhaust sytem cool off and contract–unevenly–that noise is frequently produced.
While not every car will produce this noise under those circumstances, I have found that a fairly large percentage of cars will do this. I first noticed this on my father’s brand-new '66 Ford Galaxie 500, and I have heard it on recent models of various makes.
Some cars will make this noise when new and then the noise will subside after a few months.
In other cases, the noise appears after the car has aged a bit.
The good news is that this is not something that you need to worry about.
The guess of the noise coming from the exhaust system is probably correct. If so, it is totally harmless. Another possibility is that it is coming from the fuel tank. The tank is under a partial vacuum when the engine is running. This is an anti-pollution measure. When the engine shuts down the vacuum pump stops and sheet metal, if distorted, can return to its original shape. Just another guess. Again, I would not be concerned over the noise.
Thank you for the reply.
My son and I thought at first that it was the fuel tank. We felt it was pressure/vacuum related. Thank you for your reply.