What is the flipping noise coming from under the gas pedal of my 1998 Caravan? The sound starts at about 30 miles an hour. I can only hear it when the car is coasting and not when I am stepping on the gas. The van has 142,000 and otherwise runs well.
My guess is that it might be a vacuum-controlled door in the vent system opening and closing. Lifting your foot drops the vacuum sharply and it might affect the position of the door. If this guess is accurate you face only a nuisance that can safely be ignored. Let’s hear some other guesses.
Until I read “I can only hear it when the car is coasting”, I thought there may be a loose plastic splash guard or shroud of some kind.