Car Makes a Rattling Noise When Accelerating: Why & How to Fix

You’re driving down the road, minding your own business, when you suddenly hear a strange rattling noise coming from your car. It’s most noticeable when you step on the gas, and it’s just enough to make you worry about what could be wrong. But what causes the rattling noise when accelerating?

If your car makes a rattling noise when accelerating, it could be due to loose suspension, misaligned driveshaft, loose exhaust system, faulty wheel bearings, worn-out pistons, or low transmission fluid. Easy fixes include tightening the loose parts, replacing faulty ones, and topping up the fluid.

Read on for a rundown of the possible reasons why your car is making that rattling noise and the steps you can take to fix it.

Why Your Car Makes a Rattling Noise When Accelerating

If your car is making a rattling noise when accelerating, it could be due to various reasons. With a bit of investigation and some troubleshooting, you should figure out the source of the problem and get it fixed.

Let’s look at some of the most common reasons for a rattling noise when accelerating:

Suspension System Is Loose or Worn Out

One of the most common reasons for a rattling noise when accelerating is a problem with the suspension system. The suspension system includes all components that connect the car’s body to the wheels, including the shocks and struts.

With time, the suspension components can become loose or worn out. When this happens, they can start to make noise, especially when you accelerate or go over bumps or potholes in the road.

Besides the rattling noise, signs that the suspension system is loose or worn out include:

  • A bouncy ride: When the shocks and struts are worn out, they can’t do their job correctly, which results in a bouncy ride.
  • Uneven tire wear: Worn-out shocks and struts can cause the tires to wear unevenly, eventually forcing you to replace them.
  • Swaying or leaning when driving: A loose or worn-out suspension cannot provide the support that the car needs, which can cause it to sway or lean when making turns or driving on uneven roads.

The typical causes of suspension system wear and tear are:

  • Regular use: The more you drive your car, the more wear and tear it will experience on the suspension system.
  • Harsh driving conditions: If you often drive on rough roads or in bad weather, the suspension system will experience more wear and tear.
  • Poor maintenance: If you don’t keep up with the recommended tune-ups and maintenance procedures, it can accelerate wear and tear on the suspension system.

Motor Mounts Are Loose

Another common reason for a rattling noise when accelerating is due to loose motor mounts. The motor mounts are what secure the engine to the car’s frame. If they become loose, it can cause the engine to move around and make a rattling noise.

As the loose engine shakes, it can damage other parts, such as the radiator hoses and electrical wiring.

In addition to the rattling noise, signs that the motor mounts are loose include:

  • Engine vibration: Loose engine mounts cannot provide the stability that the engine needs, which can cause it to vibrate.
  • Misaligned wheels: If the engine is shaking, it can cause the wheels to become misaligned.
  • Excessive wear and tear on other engine parts: A loose engine can cause other components to wear out prematurely.
  • Leaking oil: If the engine is shaking, it can cause the seals and gaskets to become loose, causing oil leaks.
  • The check engine light is on: A loose engine can cause the check engine light to come on.

The most common causes of loose motor mounts include:

  • Poor maintenance. If you don’t keep up with the recommended tune-ups and maintenance procedures, it can accelerate wear and tear on the motor mounts.
  • Harsh driving conditions. If you often drive on rough roads or in bad weather, the motor mounts will experience more wear and tear.
  • Modifications to the engine. If you have made modifications to the engine, it can strain the motor mounts.

Driveshaft Is Misaligned

The driveshaft is a critical part of the car’s drivetrain. It transfers power from the transmission to the rear axle, which powers the wheels. If the driveshaft becomes misaligned, it can shake and cause a rattling noise.

Additional signs that the driveshaft is misaligned include:

  • Uneven tire wear: A misaligned driveshaft places additional stress on some tires while leaving others untouched. As a result, the tires will wear unevenly.
  • Vibrations: A misaligned driveshaft can damage the suspension system. As a result, you may feel vibrations when driving.
  • Poor handling: A misaligned driveshaft results in unequal power distribution between the wheels. As a result, the car may pull to one side or the other when driving.

The typical causes of driveshaft misalignment are:

  • Worn-out suspension: If the suspension system is worn out, it can’t properly support the driveshaft, which can cause it to become misaligned.
  • Misaligned wheels: If the wheels are not aligned properly, it can cause the driveshaft to become misaligned.
  • Damaged transmission: If the transmission is damaged, it can cause the driveshaft to become misaligned.

Exhaust System Isn’t Mounted Securely

A loose exhaust system can also cause a rattling noise when accelerating. The exhaust system includes the muffler, catalytic converter, and exhaust pipes. If any of these components are loose, they may shake and cause a rattling noise.

In addition to the rattling noise, signs that the exhaust system isn’t mounted securely include:

  • A loud exhaust: A loose exhaust increases the backpressure in the exhaust system. As a result, the exhaust noise will be louder than usual.
  • Increased fuel consumption: A loose exhaust can cause the engine to work harder, which will use more fuel.
  • Decreased performance: A loose exhaust can cause the engine to lose power. This decrease in power happens due to the increased backpressure in the exhaust system.
  • A stench of exhaust gasses: A loose exhaust system may leak exhaust gasses, creating a strong odor inside the car.

The most common causes of a loose exhaust system are:

  • Poor maintenance. Skimping on regular tune-ups and maintenance can cause the exhaust system to become loose.
  • Harsh driving conditions. Driving on rough roads or in bad weather can cause the exhaust system to become loose.
  • Improper installation. If the exhaust system is not installed correctly, it can become loose.

Heat Shield Is Loose

The heat shield is a crucial component of the car that protects the engine from excessive heat. If the heat shield is loose, it may move around and cause a rattling noise.

In addition to the rattling noise, signs that the heat shield is loose include:

  • A burning smell: A loose heat shield allows hot gasses to escape and burn nearby components, resulting in a burning smell.
  • Decreased performance: A loose heat shield can damage the engine, causing power loss.
  • Overheating: Excessive heat may build up around the engine if the heat shield is loose.

Typical causes of a loose heat shield include:

  • A collision: A car accident can damage the heat shield and cause it to become loose.
  • Corrosion: Over time, the heat shield may corrode and become loose.
  • Wear and tear: The heat shield may eventually become loose with regular use.

Wheel Bearings Are Worn Out

Worn-out wheel bearings can also cause a rattling noise when accelerating. Wheel bearings are the components that keep the wheels attached to the car. If they’re worn out, they may not be able to hold the car’s weight, which can cause the wheels to shake and make a rattling noise.

In addition to the rattling noise, signs that the wheel bearings are worn out include:

  • Wheel wobble: Worn-out bearings cause uneven weight distribution on the wheels, causing them to wobble.
  • Excessive or uneven tire wear: Faulty wheel bearings can cause the tires to wear down unevenly. This wear is due to the uneven weight distribution on the wheels.
  • Increased fuel consumption: Worn-out wheel bearings cause the car to work harder, increasing fuel consumption.

The most common causes of worn-out wheel bearings include:

  • A collision: A car accident can damage the wheel bearings and cause them to wear out.
  • Bad driving habits: Driving aggressively or braking harshly can cause the wheel bearings to wear out.
  • Wear and tear: The wheel bearings may eventually wear out with regular use.

Piston Is Worn Out

Another possible reason for a rattling noise when accelerating is due to a worn-out piston. The piston is a crucial engine component that helps drive the car. If it’s worn out, it may hit the sides of the cylinder, causing a rattling noise.

Additional signs that the piston is worn out include:

  • The engine is running rough: A worn-out piston can cause the engine to run rough due to the incorrect timing of the fuel and air mixture.
  • The check engine light comes on: The check engine light comes on when there is a problem with the car’s engine. If the light comes on and you notice a rattling noise, it’s likely due to a worn-out piston.
  • Decreased fuel economy: A worn-out piston can cause the car to use more fuel due to the inefficient combustion of the fuel and air mixture.

The most common causes of a worn-out piston include:

  • A collision: A car accident can damage the piston and cause it to wear out prematurely.
  • Normal wear and tear: The piston can wear down over time due to regular use.

Transmission Fluid Is Low

Transmission fluid lubricates and cools the gears in the transmission. It can cause the gears to overheat and make a rattling noise if it’s low.

In addition to the rattling noise, other signs that the transmission fluid is low include:

  • Difficulty shifting gears: Low transmission fluid can cause the gears to stick and not shift correctly.
  • The transmission slips: If the transmission fluid is low, it can cause the transmission to slip out of gear.
  • The car jerks when accelerating: The vehicle may jerk due to the gears’ lack of lubrication and cooling.

The most common causes of low transmission fluid include:

  • A transmission leak: This can cause the fluid to drain out, leading to low fluid levels.
  • Not changing the fluid regularly: If the transmission fluid isn’t changed regularly, it can become dirty and low on lubrication.
  • Bad driving habits: Driving aggressively or braking harshly can cause the transmission fluid to become low.

For more insights into the common noises a car makes and how to fix them, I recommend that you watch the following video:

How to Fix Rattling Noise When Accelerating

Now that you have an overview of the common causes of rattling noise when accelerating, you’re probably wondering how to fix them.

Here’s a rundown of what you can do to fix the problem.

1. Fix the Suspension System

If you suspect that the suspension system is loose or worn out, you’ll need to fix it and repair the faulty components. To do so, follow these steps:

  1. Jack up the car and remove the wheels.
  2. Inspect the suspension components for damage, wear, or looseness. These include the shocks, struts, and coil springs.
  3. If any of the components are damaged, replace them with new ones.
  4. Tighten all the suspension components to the manufacturer’s specifications.
  5. Replace the wheels and lower the car.

Caveat: If you’re not comfortable doing this repair yourself, take the car to a professional mechanic. Otherwise, ensure you read your car’s owner’s manual for proper installation instructions.

That said, if you need a quality jack, I recommend this E-HEELP Car Jack Kit from Amazon. It comes with sturdy, durable steel construction and is pretty easy to use, making it an excellent fan for the money.

2. Tighten the Motor Mounts

If the engine mounts are loose, you must tighten them to stop the rattling noise when accelerating.

To tighten the motor mounts, follow these steps:

  1. Stop your car and park it on a level surface.
  2. Turn the car off and disconnect the battery terminals.
  3. Open the hood and locate the engine mounts.
  4. Use a wrench to tighten the bolts that hold the engine mounts in place.
  5. Tighten the bolts until they are snug, but don’t over tighten them.

Note: If you’re unsure how to tighten the motor mounts, consult your car’s owner’s manual or take the vehicle to a professional mechanic.

3. Align the Driveshaft

If the driveshaft is misaligned, realigning it can stop the rattling noise when accelerating. To align the driveshaft, follow these steps:

  1. Park the car on a level surface and apply the parking brake.
  2. Jack up the vehicle and support it with jack stands.
  3. Crawl underneath the car and locate the driveshaft. It’s typically between the front wheels and the gearbox.
  4. Using a socket wrench, loosen the bolts that hold the driveshaft in place.
  5. Align the driveshaft with the gearbox and tighten the bolts.

Caution: Make sure the driveshaft is correctly aligned before tightening the bolts. If it’s not, you can damage the driveshaft and transmission. Also, if you are not confident in your ability to align the driveshaft, take the car to a professional mechanic.

4. Secure the Exhaust System in Place

To secure the exhaust system in place, follow these steps:

  1. Jack up the car and support it with jack stands.
  2. Crawl underneath the car and locate the exhaust system.
  3. Using a socket wrench, loosen the bolts that hold the exhaust system in place.
  4. Reposition the exhaust system so that it doesn’t touch other parts of the car.
  5. Tighten the bolts to secure the exhaust system in place.

Caution: Be careful not to damage the exhaust system when repositioning it. If there are any corroded or damaged parts, replace them with new ones before tightening the bolts.

See also: How To Make Your Exhaust Quieter

5. Secure the Heat Shield in Place

If the heat shield is loose, you’ll need to secure it in place to stop the rattling noise when accelerating. To do so, follow these steps:

  1. Jack up the car and support it with jack stands.
  2. Crawl underneath the car and locate the heat shield.
  3. Tighten the screws that hold the heat shield in place using a screwdriver.

Tip: In some cases, you may need to replace the heat shield if it’s damaged or corroded.

6. Replace the Wheel Bearings

If the wheel bearings are worn out, they’ll need to be replaced. To do so, follow these steps:

  1. Jack up the car and support it with jack stands.
  2. Crawl underneath the car and locate the wheel bearings.
  3. Remove the wheel bearings by removing the bolts that hold them in place.
  4. Replace the wheel bearings with new ones.

Tip: Ensure you read your car’s manual for the proper installation instructions. Also, it will help you get suitable wheel bearings for your car.

7. Replace the Piston

If the piston is worn out, it’ll need to be replaced. However, this is a fairly complicated process involving removing other components like the cylinder head, so it’s best to have a professional mechanic do it.

A qualified mechanic may also help you determine if there are additional issues to address beyond the rattling noise when accelerating.

8. Top Up the Transmission Fluid

If the transmission fluid level is low, you must add more to stop the rattling noise when accelerating. Here’s how:

  1. Park your car and turn it off.
  2. Open the hood and locate the transmission dipstick.
  3. Remove the dipstick and wipe it clean with a rag.
  4. Reinsert the dipstick and pull it out again to check the fluid level.
  5. If the transmission fluid level is low, add more transmission fluid to the dipstick.

Warning: Be careful not to overfill the transmission. It can overflow and can damage engine parts due to excess pressure.

Final Thoughts

A rattling sound when accelerating could be a quick fix if you know where to look. It is essential to inspect all the components listed above to solve your particular issues. However, if you’re not confident in your ability to fix the problem, take the car to a professional mechanic to properly diagnose and fix the issue. After all, it is better to be safe than sorry!

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