Why Car Starter Motor Spins yet Fails to Engage and Turn the Engine Over (+What to Do)

Car starter issues come in various forms. This post looks at a case where the starter motor spins, does not engage the flywheel, and therefore is not able to turn the engine over.

If you want to know why this happens and what you can do to fix it then this post is for you.

Here, you’ll find the likely cause of the starter motor running but not engaging and what you can do to fix them so that you get your car starting again.

3 Main Reasons a Car Starter Motor Spins but does not Engage the Flywheel

Here are the top 3 reasons why this happens

#1. The car starter motor has a faulty. A faulty starter may not be able to engage the system that moves the pinion gear to lock with the flex plate and turn the engine over.

This can be caused by a stuck solenoid. You may be able to release the stuck mechanism by tapping the car starter with a rubber hammer to release the stuck solenoid.

If there have been repairs on the starter then it is also possible that it may not have been adjusted properly and therefore the drive lever is not able to extend as required to engage the flex plate.

Car Wont Start Clicking Noise - How...
Car Wont Start Clicking Noise - How To Fix It?

Have the car starter inspected by a qualified mechanic. You may have to replace just the starter solenoid or the entire starter.

#2. Weak battery Is the battery sufficiently charged? If the battery voltage is low, the solenoid and drive lever mechanism may not have enough power to extend and hold the pion gear to lock with flywheel teeth.

A fully charged battery usually has a resting voltage of 12.5V DC and above. At 11.5V the battery is nearly or completely discharged and will not be able to start the car.

Charge the car battery or have it tested at an auto repair shop and replaced if faulty.

#3. The Flex plate has worn or damaged teeth. It is possible too that the teeth on the flex plate might be worn in one spot or in several around the flex plate.

When this happens, you’ll hear the grinding sound as the pinion gear gets in contact with the flex plate teeth but since there is no alignment it fails to engage.

You’ll probably have to replace the flex plate. Have the car inspected by a qualified mechanic.

Signs that a Car Starter Motor is not Engaging the Flywheel

When the starter motor fails to engage the flex plate, all you’ll hear is a whirring sound, like that of an electric motor spinning but no engine crank and car engine turning over.

Related Questions

#1. Can a Starter Spin and not Engage the flywheel?

Yes, it is possible for a car starter motor to spin yet fail to engage the flywheel. This may be because the starter motor is faulty, the battery voltage is low or the flywheel has broken or worn teeth. Check this section for more information.

#2. What Causes a Starter Bendix not to Engage the Flywheel?

The mechanism for locking the starter pinion gear with the ring gear on the flywheel (the Bendix) may be just stuck, unable to move the pinion gear, broken or the car’s battery voltage may be low.

You may be able to release it by hitting it gently with a rubber hammer to minimize mechanical damage, replace it, or just charge the car battery to get it engaging.

Closing Thoughts

if the starter motor spins (you hear the whirring sound) but fails to turn the engine over then it’s usually one of, a faulty starter or its component, a weak battery, or the worn-out teeth on the ring gear of the flex plate.

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