How Does a Starter Motor Work?

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.


Next Step

Schedule Car is not starting Inspection

The most popular service booked by readers of this article is Car is not starting Inspection. Once the problem has been diagnosed, you will be provided with an upfront quote for the recommended fix and receive $20.00 off as a credit towards the repair. YourMechanic’s technicians bring the dealership to you by performing this job at your home or office 7-days a week between 7AM-9PM. We currently cover over 2,000 cities and have 100k+ 5-star reviews... LEARN MORE

SEE PRICING & SCHEDULING

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

Recent Car is not starting Inspection reviews

Excellent Rating

(12,843)

Rating Summary
11,838
514
88
99
304
11,838
514
88
99
304

Corey

16 years of experience
136 reviews
Corey
16 years of experience
Jeep Patriot - Car is not starting - Charlotte, North Carolina
Corey was awesome! Very knowledgeable, he knew what was wrong with my car by just looking at it! He went the extra mile!
Nissan Sentra - Car is not starting - Charlotte, North Carolina
Corey was quick and thorough with his inspection. I usually do not like dealing with mechanics as a female as some try ang get over on you, but Corey was honest and I trust his advice.

Pierre

9 years of experience
187 reviews
Pierre
9 years of experience
Jeep Liberty - Car is not starting - Boston, Massachusetts
Pierre was professional, friendly, efficient and extremely effective. He determined the issue and fixed the problem right away. Highly recommend his service and will absolutely use this company again.
Ram ProMaster 3500 - Car is not starting - Quincy, Massachusetts
Pierre was communicative, transparent, and committed to finding answers to my problem. Even though he was not able to fix the problem, I had more information to bring to a mechanic than ever before and am more informed about where the problem is coming from. Highly recommend!

Pardeep

21 years of experience
863 reviews
Pardeep
21 years of experience
BMW 325i - Car is not starting - San Jose, California
Pardeep is very knowledgable and capable to fix my problem ( car not start due to broken starter). He quickly diagnosed my car and found the issue. Then he ordered the part and replace it soon. The whole process was very smooth.
Ford Explorer - Car is not starting - Fremont, California
Pardeep was very knowledge on my issue. He did a few underhood tests, Then he was able to explain my issue. Unfortunately he was unable to do the repair. I thank him for assisting me with true information that will have me on the road tomorrow.!

Marco

29 years of experience
129 reviews
Marco
29 years of experience
Fiat 500L - Car is not starting - Moreno Valley, California
Marco is amazing! He was able to diagnose the issue with my car and give me a list of work that still needed to be done and list it by priority. Would highly recommend to everyone!
Chevrolet Corvair - Car is not starting - Ontario, California
Marco ... is a top notch mechanic that was able to trouble shoot my problem and get me back on the road. He is a asset to have representing your company.

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

Related articles

How Often Do Spark Plug Wires Need to Be Changed?
Spark plugs provide the electricity necessary for combustion to happen by igniting atomized fuel in an engine's cylinders. However, they need a...
How Can Problems with the Ignition System Cause Misfiring?
Misfires Misfires are never good, and they're always a sign that there’s a problem with the engine that needs to be repaired. The problem won’t “go away on its own” and waiting too long can cause the situation to grow...
How Engine Timing Works
Your Your car engine consists of a number of rapidly moving parts, including a crankshaft, camshaft, pistons, engine valves, rods and pulleys. As the piston moves up and down, the valves move correspondingly, in and out. The crankshaft spins, and...

Related questions

My car is on anti-theft mode and I can't turn my car on. I don't have a key for that

Hey there. The vehicle has an integrated anti-theft system that can not be turned off or bypassed for a no start. If you lost all the factory keys, then you will need to have new keys made and programmed using...

Car won't start; just clicks

Hi. A clicking noise when trying to start your car and no engine movement typically means that the battery is too low to crank the engine or there may be a bad connection at the battery. If the battery and...

How do I adjust the auto door unlock?

Your vehicle can automatically unlock the doors when you finish driving, so that you can exit your vehicle more easily. These settings can be adjusted based on which doors you would like to unlock (driver door, or all doors), and...

How can we help?

Our service team is available 7 days a week, Monday - Friday from 6 AM to 5 PM PST, Saturday - Sunday 7 AM - 4 PM PST.

1 (855) 347-2779 · hi@yourmechanic.com