Automotive Service Excellence (ASE) A6 Electrical/Electronic SystemsStarting System Diagnosis and RepairMedium
A technician is diagnosing a starting issue where the starter motor engages the flywheel but then makes a loud grinding noise and fails to crank the engine. A visual inspection reveals several chipped teeth on the flywheel ring gear. What is the most appropriate repair?
- AAdjust the starter motor's pinion gear clearance.
- BReplace only the starter motor's pinion gear.
- CReplace the starter motor and the flywheel/flexplate.
- DReplace the starter motor only.
Show answer & explanationAnswer & explanation
Correct answer: C. Replace the starter motor and the flywheel/flexplate.
Chipped teeth on the flywheel ring gear prevent proper engagement and can damage a new starter's pinion gear. Therefore, both the damaged flywheel/flexplate and the starter motor (which likely also has damaged pinion teeth due to the grinding) must be replaced to ensure a lasting repair.
Why the other options are wrong
- A. Adjusting clearance won't fix chipped teeth on the flywheel or a likely damaged pinion gear.
- B. While the pinion gear is likely damaged, it's typically an integral part of the starter drive assembly, and the flywheel also needs replacement.
- D. Replacing only the starter motor would lead to the new starter's pinion gear being damaged by the chipped flywheel teeth.
Flywheel Ring Gear Damage
Damage to the flywheel ring gear, often caused by improper starter engagement, leading to grinding noises and no-start conditions.
- Symptoms include grinding noise during starting.
- Requires replacement of the flywheel/flexplate.
- Often necessitates replacement of the starter motor due to secondary damage to the pinion gear.
Memory trick: Grinding gears and chipped teeth mean both parts need a new lease.