DIY

5 Signs of a Bad Starter

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When a car doesn’t start, many people assume that the starter motor is to blame. After all, the component has the term “start” right in its name. But in reality, there are dozens of potential reasons why a car might not fire up.

That’s why it’s helpful to know the symptoms of a bad starter. Once you have an idea of what to look for, you (or your mechanic) can perform a thorough diagnosis to confirm whether the starter is to blame.

vehicle starter motor
Problems with other parts of a vehicle can mimic many of the symptoms associated with a bad starter.

Bad Starter Symptoms

The starter is a small motor (with a drive assembly) that turns the engine over to get the car started.

It’s important to note that the starter turns (cranks) the engine. If your engine cranks normally but does not start, the starter motor is not to blame. Such a scenario points toward an issue with air/fuel delivery, spark delivery, or compression, rather than a bad starter.

Another thing to remember is that problems with other parts of the vehicle can mimic many of the symptoms associated with a bad starter. Never assume the starter is to blame without doing some troubleshooting.

With that in mind, let’s take a look at the common symptoms of a bad starter:

Engine Won’t Crank or Start

The most obvious sign of a bad starter is an engine that won’t crank or start. Of course, there are many other issues besides a bad starter that can prevent the engine from cranking. A few examples include a bad battery, failed ignition switch, or an engine mechanical problem.

If you hear a rapid clicking when trying to start the car, that usually points to a bad battery.

In any scenario, you’ll want to perform a thorough diagnosis to determine the root cause of the car not starting.

Engine Cranks Slowly

An internal problem with the starter motor can cause the engine to crank slowly. But the problem can also be caused by other issues, such as a weak battery or internal engine problem.

You’ll need to do your homework to determine whether the starter is to blame.

starter motor
An internal problem with the starter motor can cause the engine to crank slowly.

Grinding Noise While Starting the Engine

If the teeth on the starter pinion gear are damaged, or the starter fails to retract soon enough once the engine is running, you’ll hear a grinding noise while starting the engine.

The problem can also result from damaged teeth on the flywheel (or flexplate) that mesh with the starter gear.

Whirring Noise When Trying to Start the Engine

A defective starter drive can allow the pinion gear to freewheel during engine cranking, resulting in a whirring or whining noise. In most cases, because the pinion gear isn’t engaging the flywheel properly, the engine will also fail to crank.

Engine Intermittently Fails to Crank or Start

Like most other electrical devices, the starter motor can experience intermittent failure, resulting in an engine that occasionally fails to crank or start.

How Does a Starter Work?

The starter contains a motor, as well as a drive assembly with a pinion gear. During cranking, the pinion gear meshes with the engine’s toothed flywheel (or a flexplate if the car has an automatic transmission).

Most starters also contain a solenoid (though the solenoid or relay can be located remotely) that acts as a type of switch to engage the starter.

When you turn the key to start your car, the solenoid closes the circuit between the battery and the starter motor. At the same time, the solenoid moves the starter pinion gear forward so that it engages the flywheel.

The starter motor then spins the pinion gear, which, in turn, rotates the flywheel to crank the engine.

How Do You Troubleshoot a Car Starter When the Car Won’t Start?

An old trick mechanics often use is to bang on the starter with a rubber mallet to see if the engine cranks.

If the car starts after the starter is given a few whacks, you know the starter is faulty.

The problem is the rubber mallet test only works in limited instances. To properly diagnose the starter in a no-crank situation, you’ll want to follow the steps outlined below.

Note: The following are general guidelines for educational and entertainment purposes only. Consult your vehicle’s factory information for specific repair instructions and recommended safety procedures.

car key in starter
The starter is a small motor that turns the engine over to get the car started.

Test the Battery

Because batteries fail far more often than starters, you’ll want to test the battery before you go any further. Make sure the battery terminals are also clean and tight, and that the battery cables are in good condition.

You can test a battery’s state of charge using a digital multimeter (DMM). To do so, follow these steps:

Here is a video that demonstrates the steps above:

Check that Power is Getting to the Starter Solenoid

If the battery is okay, next, you’ll want to ensure that power is getting to the solenoid on top of the starter. You can do this with a DMM.

Here’s how it’s done:

On the other hand, if there’s battery voltage present all the way to the solenoid, the starter is likely faulty. But there are a couple of additional steps you should take to be sure.

Here is a video that (starting at about the seven-minute mark) demonstrates the steps above:

Bench Test the Starter

By this point, you’ve ensured battery voltage is getting to the solenoid on top of the starter. That rules out a control circuit problem and points to either a bad starter, high resistance in the starter power/ground circuits, or an engine mechanical problem.

To confirm the starter is to blame, you’ll want to remove it and bench test it. Your local auto parts store can bench test the starter for you, or you can attempt to test it yourself, as outlined in the video below:

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Author

Mia Bevacqua

Chief Mechanic at CarParts.com

Mia Bevacqua is an automotive expert with over 15 years of industry experience. She holds ASE Master, L1, L2, and L3 Advanced Level Specialist certification, as well as a bachelor's degree in Advanced Automotive Systems.

Throughout her career, Mia has applied her skills toward automotive failure analysis inspections, consulting, diagnostic software development, and of course, freelance writing. Today, she writes for companies around the world, with many well-known clients showcasing her work.

Mia has a passion for math, science, and technology that motivates her to stay on top of the latest industry trends, such as electric vehicles and autonomous systems. At the same time, she has a weakness for fixer-upper oddballs, such as her 1987 Chevy Cavalier Z-24 and 1998 Chevy Astro Van AWD.

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