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How to Fix a Car Making Rattling Noise When Accelerating?

Annoying rattling noises from your car when you accelerate are nerve-wracking when you don’t know if it affects the safety and drivability of your car. Whether major or minor, a rattling noise from a car as it accelerates is a sign of something seriously wrong and should not be ignored.

A car can make a rattling noise when accelerating because of a loose exhaust system, worn-out suspension, a poorly lubricated transmission, loose engine or transmission mounts, and worn-out heat sinks. Fixes include replacing faulty parts, tightening loose ones, and topping up the concerned fluids.

Fix a Car Making Rattling Noise When Accelerating

In this article, I will discuss how to find out the source of a car rattle when accelerating and how to fix it once you know where the problem lies.

Also read: Car Making Clicking Noise When Driving? Find Out Why!

Rattling Noise When Speeding Up: What It Says About Your Car and How To Fix It

Your car making rattling noise when accelerating or driving at highway speeds indicates that it might be time to take a closer look at what’s happening with your car. 

1. The Exhaust System May Be Loose

First, it is good to rule out the simple things before considering engine and transmission issues. A loose exhaust system will cause rattling as you accelerate when the exhaust manifold bangs on other car parts

This rattling will increase with speed and may not be heard when the car is at low speeds below 20mph (32 kph). Acceleration generates and transmits massive amounts of energy through the transmission system, which causes a car to shake. 

As the car shakes, the loose exhaust system will bang on the body and cause rattling sounds.

Other possible signs that your exhaust system is not securely attached include

  • A stench of exhaust gases.
  • Loud exhaust rumbles that were previously unheard.
  • Decreased performance.
  • Increased fuel consumption.

Some things that may make the exhaust loose are

  • Bad driving conditions
  • Harsh driving habits characterized by rough acceleration
  • Improper installation of the exhaust system

Here are some tips on how to fix this problem:

  1. Inspect your exhaust system while the engine is running. Ensure the gear is not engaged. 
  2. Note if the exhaust is loose and shaky, smoke leakages, and listen for strange noises. You can grab the exhaust tip at the back and try to shake. 

If you identify the exhaust as the culprit, you must secure it. You can fix the bolts and mounts yourself or engage a qualified mechanic. For exhaust rumbles that are a sign of leakage, you need to take your car to a mech for the identification of the leakage and sealing. 

2. Suspension Parts Are Worn Out

The suspension system is crucial for a car’s ability to control its motion. It connects the car’s body to the wheels through shock absorbers, struts, stabilizer links, rods, and bushings. 

When one of these components becomes loose or wears out, you should expect a rattling noise, considering that the suspension system absorbs the shocks that the wheels generate as they roll on the road. 

The rattling noise from your suspension system will be worse when you drive through a rough road or over bumps.

Besides the rattles, other signs of a damaged suspension system include the following:

  • A bouncy ride
  • Excessive vibrations
  • A swaying or leaning on one side
  • Uneven tire wear 

To fix this problem, get your suspension system checked by a qualified mechanic. I do not recommend doing this yourself because some of the suspension parts are in hard-to-reach places. 

For these parts to be accessed, your car has to be lifted. On top of that, some suspension wear may not be visible to the untrained eye.

Possible causes of suspension wear and tear include 

  • Poor maintenance
  • Harsh driving
  • Overloading

3. Damaged Heat Shields 

Your car has several heat shields to protect parts from excessive heat. These heat shields include 

  • A thermo-protective barrier between your exhaust system and other car parts. 
  • Heat shields in the engine bay area to prevent heat damage to internal components and bodywork. 

The heat shield can break due to rust or crack, causing a rattling noise as the car accelerates. 

Other signs that your heat shields are damaged include:

  • Excessive cabin heat
  • An overheating engine
  • A burning smell from under the hood or car body
  • Decreased performance

The easiest fix is inspecting your car to identify the worn-out shield and then replacing it. 

While at it, consider insulating your entire car from heat, sound, and dust. Car deadening will make your ride more comfortable and can mute the rattling sounds.

car deadening
Car Sound Deadening

Some issues that may damage your heat shields include:

  • Normal wear and tear
  • Impact of collision accidents
  • Corrosion from rust

You should replace a damaged heat shield as soon as possible to reduce the risks of deadly fires and accidents when heat damages a part, such as a fuel or a brake line.

4. Worn-Out or Loose Engine Mounts

Your engine and transmission are mounted to the car frame through motor mounts. These mounts secure your engine and transmission to the car frame while reducing noise and vibrations. 

When a mount becomes loose or worn out, it will allow your engine or gear to move around during acceleration, and this can cause rattling sounds. As your engine shakes and moves about due to faulty mounts, it will damage other parts. 

Commonly, faulty mounts will cause the engine to incline towards one side, misaligning drive shafts. The misaligned shafts can cause a rattling noise themselves and bring about many other complications.

Damaged engine mounts also show additional signs. 

  • Engine vibrations
  • Oil leakages
  • Excessive damage to other engine parts
  • Misaligned wheels

Have your motor mounts checked by a qualified technician as soon as possible, and don’t try to fix the problem yourself. The mountings have some hydraulic shields that, at times, leak hydraulic fluid, which might be challenging to detect.

5. Transmission Issues

When transmission fluid gets low, your car may start making rattling sounds. Low transmission fluid can cause gears to overheat and make the sounds worse. 

Other signs of low transmission fluid include 

  • Difficulty in changing gears
  • Transmission slips
  • Car jerking as it speeds

Here are some possible causes of low transmission fluid. 

  • Transmission leaks
  • Bad driving habits
  • Poor maintenance 

How to Fix Transmission Issues Leading to Car Making Rattling Noise When Accelerating

You can fix rattling noises caused by transmission issues easily. Here are simple steps to follow to prevent your gears from overheating.

  1. Check your transmission fluid levels
  2. If the fluid is low, drain and refill with new transmission oil; topping up is not a good idea.
  3. Ensure you service your transmission regularly to lower the chances of leaks.

6. Worn-Out Wheel Bearings

When your wheel bearings wear out, they may cause rattling sounds. Wheel bearings attach the wheel to the wheel hub, and when they wear out, they can make the car shake and rattle.

Other symptoms of worn-out bearings include

  • Excessive wobble 
  • Increased fuel consumption

Causes of wheel bearing wear and tear include

  • Bad driving habits
  • Collision accidents
  • Normal wear and tear

To address this issue, get a qualified mechanic to check your wheel bearings and advice accordingly. 

Final Thoughts

Your car rattling when accelerating is a sign of serious issues with the internal components. Ignoring car rattles can put you at risk for some causes of rattling sounds are serious mechanical issues. 

Check your car or get it checked by a qualified technician and address the cause of the rattling urgently. The rattles can lead to something more serious and increase repair costs.