A screw extractor, commonly called an Easy Out, is a tool that removes broken bolts. When a bolt head snaps off flush with the engine block or bracket, standard tools cannot grip it. The extractor is made of hardened steel and features left-hand spiral threads. You drill a pilot hole into the center of the broken stud, insert the extractor, and turn it counterclockwise. As you turn, the left-hand threads bite into the metal, backing the broken bolt out.
Drilling the pilot hole straight and centered is the most critical step. If the hole is off-center, you will drill into the engine block's threads, ruining the hole. Use a center punch to mark the middle of the stud before drilling. If the extractor snaps inside the bolt, you will have a major problem. Extractor steel is extremely hard, meaning standard drill bits cannot cut through it. Apply heat and penetrating oil to seized bolts before attempting extraction.