Occasional hooting sound.

[bodabdan]

You mentioned that it may have started after your expansion rank was replaced. Any chance you're hearing the cap as it's venting excess pressure?

 

[99WhiteC5Coupe]

You mentioned that it may have started after your expansion rank was replaced. Any chance you're hearing the cap as it's venting excess pressure?

Not sure.

After the tank and cap was replaced by the Ford dealer (for a leak) - I bought another cap from Ford and changed it. No change in the sound.

The noise will begin after starting the vehicle and driving away (slow speed), after the vehicle has been parked overnight. Hot or cold ambient temperature doesn’t seem to have any affect on the sound.

 

[99WhiteC5Coupe]

Any idea what this sound is. You can’t predict when it will happen. It will be two to four descending notes. Usually happens when I let off the gas. Listen to the sound in the following link. Kind of sounds like a cuckoo. https://photos.app.goo.gl/afKE2fcQaEvswg4d8

Were you able to determine the cause of this sound?

 

[adwmac6]

any update?