The Chrysler K-Car Club

Last few times I have had my '82 Lebaron out (2.6 auto) it sounded like I had an exhaust leak up by the engine. After investigating I took the air filter out and the noise is coming from the tube inside the air cleaner housing. I plug it with my finger and the noise quiets but I can feel pressure in the tube. It looks like it is connected to a hose/pipe that goes in front of the engine and under the carburetor somewhere but I can't see what it connects to. What does this tube do and what problem do I have as I never noticed the noise before until the last few times I drove the car.