Free ASE A-Series Auto Technician Tests (A1-A8) Flashcards

Suspect a cracked flexplate before suspecting a rod or main bearing. In Park and Neutral the flexplate carries no load and the crack faces can sit together quietly; shifting into a driving gear applies torque through the flexplate to the torque converter, opening the crack and producing an impact noise once per revolution. A true rod-bearing knock is driven by combustion and oil-film load and is normally present in Park/Neutral too, just louder under load, so a noise that is completely silent out of gear and appears only in gear points specifically at the flexplate-to-converter interface rather than the bottom end.