What makes a thumping noise under a van?

A thumping noise under a van can be caused by several issues, including a loose or damaged exhaust system, worn-out suspension components, or a failing drive shaft. It could also be a sign of debris caught in the undercarriage or an issue with the tires, such as uneven wear or a broken belt. If the noise persists, it's advisable to have a mechanic inspect the vehicle to identify and resolve the underlying problem.