Scavenge /(?)/

Scav·enge

Scavenge

v. t.
  1. To cleanse, as streets, from filth.
  2. to salvage (usable items or material) from discarded or waste material.
  3. To remove (burned gases) from the cylinder after a working stroke.

Scavenge

v. i.
  1. To remove the burned gases from the cylinder after a working stroke; as, this engine does not scavenge well. (Internal-combustion Engines)