5 Reasons Why Your Starter Is Not Engaging & How To Fix It

If your starter spins without engaging the flywheel, you definitely have a problem. Here is how to fix it and diagnose the starter

Starter Not Engaging

Picture this: You have an early morning presentation with seed investors. It is a meeting that is going to change your life.

You pop into your garage in a hurry, but the car will not start when you turn the ignition key.

You can hear the starter spinning, but it’s not engaging with the flywheel. What could be wrong? What could cause your starter to not engage with the flywheel?

Reasons Why Your Starter Is Not Engaging

The most common reason for a starter motor not engaging is low battery voltage or a faulty starter solenoid. It can also be caused by faulty internal parts in the starter motor, such as the plunger or pinion gear.

There could be many other reasons causing your starter not to engage properly, but generally speaking, it will be an internal issue with the starter motor. Here is a more detailed list of the 5 most common causes why your starter won’t engage.

1. Low battery voltage

Bad Car Battery

When you are experiencing battery problems, the first culprit is your battery voltage, so you should check this first. The battery powers the starter, and if it is not working, the starter will fail to engage completely.

Charge your car battery fully. You can even try to replace the car battery if you have another one you know works. You can also try jump-starting your car from the car battery of another car if you have the knowledge.

Next, check out whether your battery terminals are corroded. For this, you will notice a whitish or greenish substance on the terminals.

If you notice any corrosion on the battery terminals, you should remove the battery cable clamps and remove the terminals carefully.

RELATED: Does Auto-Start/Stop Wear Out Engine Components?

2. Starter solenoid

Starter Solenoid

The starter solenoid is located on top of the starter. When you turn the key, it is the starter solenoid that pushes a plunger inside the starter motor, pushing the pinion toward the flywheel.

Use a jumper wire to ground the solenoid to a bolt. Start the ignition and listen for sounds coming from the solenoid. If the click is loud and solid, then the solenoid is working fine, but if you hear a weak click, then recheck the wiring between the solenoid and starter. Electrical wires can, with time, become dirty, loose, and broken.

3. Starter motor Plunger or Pinion

Starter Motor Diagram

If your starter solenoid seems to be fine, there might be another problem inside the starter motor. The parts that can accomplish this are the starter plunger or the starter pinion.

It is time to dismantle the starter and check inside for the pinion gears. These are often placed at the front of the starter. The pinion gears engage the flywheel in firing up your engine.

With time, these gears get worn out and cause problems with the starter engaging. It is time to purchase a new piston gear if it moves in both directions when you try to rotate it.

RELATED: How to Start a Car with a Bad Starter (7 Steps)

4. Faulty wirings to the starter

Corrosion On Cable

There may also be a situation where the starter gets enough electricity to make a sound, but not enough to actually turn the starter. This can happen if there is a bad starter cable between the car battery and the starter or corrosion at any connection.

Clean all connections, both at the starter and the battery, to ensure there is no bad connection. You can often locate bad connections by feeling the cable connection; it will create a lot of heat if there is a bad connection.

5. Flywheel damages

Car Flywheel

You can identify the flywheel as the large wheel that is located between the engine and transmission. The starter pinion gears engage it to start the engine. What you should be looking for in a faulty flywheel are worn or damaged gears.

While the car is in neutral, rotate the crankshaft using a ratchet. As you move it, watch the behavior of the flywheel. You will need to replace it if you notice that the gears are damaged.

It would rarely happen suddenly; it is more common to have the wrong flywheel installed on the car.

Starter Testing Video

Starter FAQs

Why does my starter spin but not engage the flywheel?

If your starter motor spins but does not engage the flywheel, it could be due to a faulty starter solenoid or a bad car battery. It can also be due to other faulty internal parts of the starter motor, such as the pinion gear.

How do you manually engage a starter?

To manually engage a starter motor, you must power the starter solenoid and the starter motor connections. The easiest way to do this is to bridge the connection between the power cable and the starter solenoid. This will spin the motor, though, so be careful!

Where to hit a starter to make it work?

If you suspect the starter motor is bad, you can give it a small hit on the starter solenoid first to see if it starts the starter motor. If that doesn’t work, you can also hit the starter motor itself. Be careful while doing this, since the motor can suddenly turn over.

Will a jump help a bad starter?

A jump can help a bad starter in some cases, because of the higher voltage the starter motor will get. In most cases, a bad starter won’t turn over just because you give it more power, but it might be worth a try.

Magnus Sellén
Written by:

Magnus is the owner and main author of Mechanicbase. He has been working as a car mechanic for over 10 years, and the majority of them specialized in advanced car diagnostics and troubleshooting. Certified Automotive Diagnostic Technician.

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