Why your Car may be Making the “machine gun” Sound (+Possible Fixes)

For the most part, your car’s engine will turn over successfully when the ignition key is switched to the START position.

You may find yourself in a situation though where instead of the smooth running of the engine, you’re instead “greeted” by the frustrating, rapid clicking, machine gun sound with the car not turning over when you try to start.

What causes this and what should you do to fix it?

The good news is that in some cases, you may be able to fix the machine gun sound yourself without the services of a mechanic.

To find out how and what causes the rapid clicking, read on.

Quick answer: If a car makes a rapid clicking machine gun-like sound when you attempt to start it, it is possible that the battery voltage is low and not able to supply the starter with the required power to turn the engine over.

Read on for what else may be causing this.

What Causes the Machine Gun Sound when Starting a Car (+ What to Do)

The machine gun or rapid clicking sound comes from the car starter as it attempts to start the car engine. This sound may be heard if:

1. Either the battery positive or negative terminals are not making firm contact with the battery posts leading to a lower-than-required current draw that is not enough to power the starter and turn the car over.

The machine gun-like sound comes from repeated failed attempts by the car starter solenoid to engage (because of lack of enough power) when the ignition is turned to the start position.

Confirm that the battery terminals are firmly gripping the battery posts. Attempt to swivel the terminals or gently lift them off the battery posts.

They should hold firm and should not come off easily or turn from side to side with gentle pressure.

2. The battery terminals and posts are corroded hampering a good solid contact necessary for sufficient current to flow from the battery to the starter.

Inspect the battery terminals. Are they clean or do they have a white powdery fluffy substance that’s building up on them?

Clean the corrosion off battery terminals by mixing baking soda with warm water or any other good quality battery cleaning solution. Pour the mixture over the battery terminals.

Make sure the battery clamps make firm clean and firm contact with the battery posts.

You may also be interested in learning more about why batteries corrode and how to remove the corrosion

3. The car battery charge is low. If the contacts are firm and there’s no corrosion, it is possible that the battery charge is low and not able to consistently supply enough power for the car starter to run.

Use a good quality digital multimeter set to read voltage to measure the battery voltage.

A fully charged battery measures about 12.6 V. A battery with a voltage below 12V may not be able to start the car.

Switch off any accessories that may be draining the car battery charge such as the headlamps, sound system, blower, and others then try and start the car.

Use an external charger to charge the car battery. Make sure it is set to charge the battery type that matches your car battery.

Look out for any parasitic current draw that may be draining the battery. Do not hesitate to contact a qualified car mechanic.

A quick check on whether a car battery is able to hold charge

use an external charger to fully charge the battery and then switch on the headlights.

They should be able to light for about as long as the reserve capacity (minutes) of the battery, usually 60-90 min.

Should they dim after say 30 minutes then it is probable that the car battery is aging and losing its ability to hold charge.

You can confirm this by testing the car battery at a reputable auto parts store.

4. The car starter may be faulty too. The Starter solenoid contacts may not be closing properly. If the starter is damaged or the contacts are burnt or worn then the starter can produce the machine gun sound.

Contact a qualified mechanic. You might have to replace it with a new starter.

4. Some car owners make modifications to their car exhaust systems. The cars then make the sound of gunfire as the car is revved or accelerated.

Related Topics

1. Can a Car Sound Like Gunshots?

Yes, a car can sound like gunshots as the engine runs or the car accelerates if modifications are made to the exhaust system. Not only is this scary, it is also illegal in several cities.

2. What Causes a Car Window to Make Machine Gun-Like Sounds?

If the car window makes a machine gun sound as it rolls up or down then it is highly probable that the teeth on the gear wheels in the rollup/down system are stripped, skipping and making the machine gun sound.

Contact a qualified mechanic for assistance.

Closing Thoughts

If your car makes a machine gun sound under the hood when you try to start it, it may be one of several reasons – the car battery voltage is low, the battery connections are loose or corroded, or the car’s starter is faulty.

Do not hesitate to contact a qualified mechanic.

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