Skip the auto shop - Our mechanics make house calls
  1. Home
  2. Articles
  3. How Does a Starter Motor Work?

How Does a Starter Motor Work?

Starter Motor

When you turn the key in your car’s ignition, the engine turns over and then cranks. However, getting it to crank is actually much more involved than you might think. It requires a flow of air into the engine, which can only be achieved by creating suction (the engine does this when it turns over). If your engine isn’t turning, there’s no air. No air means that fuel can’t combust. The starter motor is responsible for turning the engine over during ignition and allowing everything else to happen.

How your starter works

Your starter is really an electric motor. It engages when you turn the ignition to “run” and turns the engine over allowing it to suck in air. On the engine, a flexplate or flywheel, with a ring gear around the edge, is attached to the end of the crankshaft. On the starter, there’s a gear designed to fit into the grooves of the ring gear (the starter gear is called a pinion gear).

When you turn the ignition switch, the starter motor is energized, and the electromagnet inside the body engages. This pushes out a rod to which the pinion gear is attached. The gear meets the flywheel, and the starter turns. This spins the engine over, sucking in air (as well as fuel). At the same time, electricity is sent through the spark plug wires to the plugs, igniting the fuel in the combustion chamber.

As the engine turns over, the starter disengages, and the electromagnet stops. The rod retracts into the starter once more, taking the pinion gear out of contact with the flywheel and preventing damage. If the pinion gear remained in contact with the flywheel, it’s possible that the engine would spin the starter too fast, causing damage to it.

The statements expressed above are only for informational purposes and should be independently verified. Please see our terms of service for more details
Icon-warranty_badge-02

Skip the repair shop, our top-rated mechanics come to you.

At your home or office

Choose from 600+ repair, maintenance & diagnostic services. Our top-rated mechanics bring all parts & tools to your location.

Fair & transparent pricing

See labor & parts costs upfront, so you can book with confidence.

12-month, 12,000-mile warranty

Our services are backed by a 12-month, 12,000-mile warranty for your peace of mind.

Get A Quote

Need Help With Your Car?

Our certified mobile mechanics make house calls in over 2,000 U.S. cities. Fast, free online quotes for your car repair.

GET A QUOTE

More related articles

What are the Car Pool Rules in Hawaii?
Hawaii is widely regarded as a land of vacation and relaxation, and as such, its scenic roads and routes are far better known than the state’s freeways. But, as with all...
P0291OBD-II Trouble Code: Cylinder 11 Injector Circuit Low
P0291 code definition When your vehicle’s PCM registers the P0291 code, it means that a voltage reading came from the fuel injector circuit – for cylinder number 11’s fuel injector –...
P0477 OBD-II Trouble Code: Exhaust Pressure Control Valve Low
P0477 code means that the PCM has detected an abnormally low voltage reading often due to the exhaust back pressure control valve circuit.

Related questions

Q: Car idles for a while and then shuts off

Hello. You will need to monitor the fuel pressure and spark plug spark at the plugs when the engine dies. I suspect you may have a defective ignition stator in the distributor. When you lose power, you should see the...

Q: Gauges not moving

Hi. A no-start condition with no rpm while cranking would leave me to suspect that the coil isn't switching. This causes your car to not produce any spark, contributing to your vehicle not starting. I would have a certified mechanic,...

Q: Q: Car won't start

Hi there! This concern plagues many vehicles and may stem from either a failing battery, or some charging system component that is not charging the battery properly (e.g., a shorted circuit that drains the battery while the car is idle)....