A car's starter. Starters rarely fail, but when they do, it's hard to ignore. Diagnosing a troublesome starter can be tough, but this helpful guide could give you a starting point.

Why Do Good Starters Go Bad?

Starters rarely fail, but being an integral component in the starting system, you’ll know it when they do. And despite the rarity, there are a number of ways and reasons a starter very quickly becomes anything but. Luckily, knowing what you’re dealing with can help diagnose or preserve the life of your current starter and help you answer a vital question: Why do good starters go bad?

Thriving Startup

A starter is an electromagnetic actuator comprised of several mechanisms working together to turn electrical energy into enough mechanical energy to “turn over” an entire engine. It actually comes down to a tiny, but strong pinion gear that thrusts toward the engine and spins, engaging the flywheel, which gets the pistons moving. Add fuel, air and spark, and the engine takes care of running itself from there.

From Starter to Finished

Most often, starters fail from wear and tear — naturally or induced by operator (or installer) error. Inside the starter is an armature, and the magnetic “brushes” that ride around it can wear out over time. The starter solenoid, which sits just outside the main casing, allows electricity to flow through the starter, and can thus be exposed to damagingly high temperatures, and are prone to arching and mechanical sticking. If you ever see or smell smoke from the starter, it is not long for this world and you should contact a professional immediately.

Tooth Be T’oldWhy Do Good Starters Go Bad?

The teeth of the pinion gear, which contacts the flywheel, can also suffer wear over time, as can the teeth of the flywheel itself. In either case, the gears will not mesh properly and the flywheel will not spin. This usually results in a grinding or whirring sound when you attempt to start the vehicle. This problem can start small with worn spots, but will be greatly and quickly exacerbated if the driver continues cranking at the ignition. So if your car ever cranks but won’t start, don’t force it or you could make things a lot worse.

Rules of Engagement

Some issues arise from poor installation. The bolts holding the starter to the engine also provide a ground for current. If they are loose, you could get electrical woes and will likely face wallowed out holes creating misalignment and damage on the flywheel and starter. But be careful to not over-tighten them, or you’ll snap the casting. The two gears must also be enmeshed in installation, or you might crack the casing and again, the engine may not spin.

Before replacing a starter, always confirm that you’re not just dealing with a dead battery, a blown fuse or a bad ignition switch. Starters aren’t usually too difficult to replace, but it’s important to take precautions like removing the battery’s negative cable first, or you’ll be in for a sparky surprise.

Knowing the basics of how a starter works and what components are likely to fail can help you answer the question of: “Why do good starters go bad?” Containing a failed component, especially one that’s as crucial as your car’s starter, can stop something bigger from happening.

Check out all of the electrical system products available on NAPA Online or trust one of our 17,000 NAPA AutoCare locations for routine maintenance and repairs. For more information on what can go wrong with your car’s starter, chat with a knowledgeable expert at your local NAPA AUTO PARTS store.

Photos courtesy of Blair Lampe.

about author

Blair Lampe

Blair Lampe is a New York-based professional mechanic, blogger, theater technician, and speechwriter.  In her downtime she enjoys backpacking wherever her boots will carry her, rock climbing, experimental theatre, a crisp rosé , and showering love on her 2001 Sierra truck.

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