14 Reasons Why Your Car Makes A Rattling Noise When Accelerating

A vehicle functions optimally when its numerous components work in harmony. Each part of a car must operate correctly and in coordination with others, or it risks leading to malfunctions in the car’s overall performance. Hearing a rattling noise while driving is definitely not a good sign. Are you hearing a rattling noise when accelerating?

When your vehicle rattles during acceleration, it’s typically indicative of an issue. Your vehicle may produce rattling noise while driving due to different causes, such as low transmission fluid, a misaligned driveshaft, damaged heat shields, and deteriorating suspension elements. While some solutions to these issues can be quite straightforward, such as tightening loose elements or refilling fluids, others may need a more professional approach for diagnosis and repair.

Reasons Why a Car Makes Rattling Noise When Accelerating

Experiencing a rattling sound while accelerating as you cruise down the road can be disturbing. There are numerous potential causes for such rattling sounds when driving, such as insufficient transmission fluid, a misaligned driveshaft, loose heat shields, and deteriorating suspension elements.

Following are the major reasons why your car rattles when accelerating:

1) Faulty Engine Mounts

A damaged or bad engine mount is one of the major causes of rattling noise while driving the vehicle.

Engine mounts are very important to ensure the proper operation of your vehicle. These specific bushings are used to secure the engine to the frame of the vehicle, dampening the impact and vibrations encountered while accelerating.

When the engine goes bad, your engine may experience excessive shaking, potentially damaging other parts of the vehicle.

You would typically observe this as a noticeable rough shaking emanating from the engine compartment during driving. This can be accompanied by various sounds like vibrations, rattles, or squeaks. Furthermore, compromised engine mounts may misalign your vehicle, resulting in irregular tire wear.

Other clear signs of malfunctioning engine mounts can include leakage of engine oil or the illumination of the check engine light on your dashboard.

Read More: Bad Engine Mount Symptoms and Causes

2) Overstretched Timing Belt

A worn timing belt is one of the major of the rattle when accelerating. The role of the timing belt is to ensure that the engine’s valves and pistons move in synchronization. When the belt deteriorates, it might slip, disrupting the timely opening and closing of the valves, thus leading to a rattling sound.

Alternatively, a worn timing belt may become excessively stretched. In such a situation, the pulleys on which the belt moves can get misaligned. This misalignment may also produce a rattling sound as the engine’s speed is increased.

3) Insufficient Engine Oil

Your engine requires a sufficient quantity of oil to ensure smooth lubrication within the engine. This lubrication prevents metal components from creating friction against each other.

But when the oil becomes insufficient, a rattling noise might be heard. This noise tends to become considerably more prominent when the vehicle accelerates.

Read More: Causes of Low Oil Pressure

4) Broken Heat Shields

The exhaust heat shield serves as a protective layer for parts that tend to heat up significantly, such as the muffler, exhaust manifold, catalytic converter, and exhaust pipes. This shield is secured directly to the exhaust system via bolts or rivets, allowing it to absorb some of the engine’s heat.

Nonetheless, over time, the heat shield may come loose due to vibrations and general wear and tear. When it sustains damage, it loosens and begins to produce a rattling sound when your car is accelerating.

The heat shield is also attached to the vehicle’s frame. If it becomes loose, it may make contact with the exhaust system, resulting in a rattling noise.

5) Worn Piston Rings

The piston ring is a metallic ring snugly fitted into the grooves on the piston’s outer edge within an engine. These rings primarily ensure a tight seal for the engine cylinder, preventing the escape of pressure generated by fuel combustion.

These rings also prevent oil from seeping into the combustion chambers. They also help to ensure adequate lubrication between the cylinder wall and the piston.

But with time, the piston ring may wear down, leading to a host of issues. One common problem is referred to as ‘piston slap’. This occurs as the ring loses its tight fit against the piston, leading to a movement that creates a pronounced rattle sound.

6) Broken Flywheel or Flexplate Teeth

The flexplate or flywheel is a metallic disc affixed to the rear of the engine. Its primary function is to transfer power from the engine to the transmission.

In addition, the flywheel plays a crucial role in preventing the crankshaft of the engine from excessive back-and-forth movement during the firing of the pistons in the power stroke. It performs this job by offering a surface for the clutch discs to hold while driving.

As the flexplate or flywheel goes bad, it may lead to a rattling noise when you try to accelerate your vehicle. This happens because the compromised surface of the flywheel will not be able to offer a smooth grip for the clutch disc. Consequently, an uneven and rough surface leads to the discs chattering.

In a few conditions, the flywheel teeth can be damaged. They play a crucial role in interacting with the starter motor. When these teeth are damaged, the starter motor may fail to engage correctly, which could also lead to a rattling sound.

Another potential cause for a car’s transmission producing rattling sounds could be an insufficient level of transmission fluid.

7) Worn Timing Belt Pulleys and Tensioners

The timing belt pulleys and tensioners each have their distinct roles. The pulley is responsible for holding the timing belt in the correct position, while the tensioner is used to ensure the belt maintains the right level of tension. These components may wear down over time, leading to a rattling noise.

Specifically, the timing belt pulley’s bearings can deteriorate that producing noise as they rotate. Moreover, if the teeth on the pulleys suffer damage, they can also produce a rattling sound.

Similarly, the timing chain tensioner can wear out over time, failing to provide adequate tension. This can lead to the timing belt slipping, which in turn results in a rattling sound.

8) Faulty Catalytic Converter

The catalytic converter is situated within the exhaust system of your vehicle. The primary function of the catalytic converter is to transform harmful exhaust gas into less detrimental ones before it is expelled into the environment.

But your vehicle’s catalytic converters may be damaged with soot and other contaminants over time. When this occurs, it may make the engine run lean, resulting in a rattling or knocking sound.

Another potential issue with the catalytic converter is a phenomenon known as thermal shock, which is when the converter gets excessively heated. In this scenario, you might observe a loud banging sound emanating from beneath the vehicle’s hood, accompanied by the sight of flames and smoke billowing from the tailpipe.

9) Weak Water Pump

The water pump plays a vital role in moving coolant throughout the engine. Over time, the bearings within the pump may wear down, leading to rattle noise.

Moreover, the impeller, which is the component of the water pump responsible for propelling the coolant, could also be damaged and may also lead to a similar rattling sound when you are driving. In such a case, it would require replacement.

Read More: Bad Water Pump Symptoms and Causes

10) Loose Interior Trim

Interior trim refers to the covering inside a car, serving to protect the interior from contaminants.

If the interior trim becomes loose, it may create a rattling noise due to it not being firmly attached to the car’s frame.

This loosening can be the result of several factors, such as a vehicular accident, normal wear, and tear, or substandard installation. In some instances, you can fix a loose interior trim by tightening it.

However, if the rattling noise stems from a more severe issue, like a damaged vehicle’s frame, then a more extensive repair may be necessary.

11) Corroded Exhaust Components

An exhaust system contains multiple components that are used to channel exhaust gas away from the engine. This typically includes a muffler, a catalytic converter, and an exhaust manifold. Its primary purpose is to mitigate noise and emissions. 

Corrosion is one of the major causes of a faulty exhaust system. Over time, the metal parts of the exhaust system may start deteriorating and wearing away, creating a rattling noise when the car is accelerating.

In extreme conditions, the corrosion can lead to the formation of a hole in the exhaust pipe. Neglecting corrosion in the exhaust system can lead to significant issues over time. If not addressed, it may also lead to the failure of the emissions test.

12) Bad Rocker Arms

If the rocker arm of your vehicle generates a rattling sound, there could be several reasons behind it. The most prevalent cause is usually insufficient lubrication of the pushrods.

The lack of adequate lubrication can lead to metal components grinding against each other. Over time, this friction will erode the surfaces of the pushrods and rocker arms, ultimately diminishing your engine’s performance.

Another potential cause is that the rocker arm itself may be worn. This scenario is less frequent but can occur if the vehicle is driven rigorously or not adequately maintained. In this situation, it would be necessary to change the rocker arms.

13) Low Oil Pressure

Insufficient oil pressure is also one of the major reasons of the rattling noise when the car is accelerating.

If oil pressure isn’t maintained at an appropriate level, it can lead to engine damage. Nevertheless, it’s important to identify the source of the pressure drop, which could be due to a blocked filter or a malfunctioning oil pump.

14) Low Transmission Fluid

Transmission fluid plays a crucial role as a lubricant for the transmission system gears. If the fluid level dips below the necessary level, your vehicle may face difficulties shifting gears. As a result, the transmission could produce a rattling noise, exhibit shaking, or even overheat.

Read More: Causes of Transmission Warning Light Illumination

How To Fix a Car That Rattles When Accelerating

Follow the below-given steps to fix a rattling noise coming from your car when accelerating:

1) Open the Hood and Listen for Noise

Utilize a cost-free diagnostic tool, your ears, to identify issues. By attentively listening, you can determine the root of the issue. Open up your vehicle’s hood and carefully listen until you successfully locate the origin of the noise.

Remember to exercise extreme caution to prevent injury. Make sure not to get too near to the moving parts, as your loose clothing, hair, or any other body parts may potentially get entangled.

2) Listen Under the Vehicle

If the rattling sound cannot be traced from the hood, the next step is to inspect the underside of your car. With the engine operating, attempt to pinpoint the source of the rattle. However, this might prove to be challenging if the noise only produces during acceleration.

Should you need to explore further beneath your vehicle, you may need to elevate it using a jack. However, safety should always be your primary concern – ensure that the vehicle is securely positioned on jack stands before you venture underneath it.

3) Tight the Loose Heat Shield

To rectify a rattling noise caused by a loose heat shield in your vehicle, you need to stabilize it. This is a fairly straightforward task that involves a series of simple steps.

• Use ramps or jacks to elevate your vehicle. After doing so, get underneath the vehicle and find faulty or loose heat shields.
• Fasten the screws that link the heat shields to the vehicle. If the screws are not present, you need to reconnect the shield by using new screws or wire. In cases where your heat shield is significantly damaged or corroded, you may have to change it altogether.

4) Tight the Engine Mounts

Rattling noise from the engine while driving may be due to a loose motor mount. However, replacement may be required in some cases, but you can often solve the problem by simply tightening the bolts that fasten the engine mounts to your car’s frame.

• Properly Park the vehicle and switch off the engine.
• Detach the negative terminal of your car battery.
• Identify the engine mounts, which are typically three or four in number. Employ a wrench or ratchet to tighten the bolts until they are comfortably secure. It’s crucial not to over-tighten the mount.
• Restart your vehicle and inspect the engine mount by putting the car in gears, maintaining brake pressure, and gently accelerating the engine. Poor motor mounts will lead to the engine violently jolting and vibrating when these actions are performed.

5) Repair the Suspension System

If you identify that the source of the rattling noise is your car’s suspension system, you must isolate the defective component and proceed with its repair.

• Use ramps or jacks to elevate your car.
• Change the damaged parts. These could include parts like tie rods, control arms, coil springs, shocks, sway bars, and struts.
• Make sure to secure all components according to the correct torque arrangements. Subsequently, perform a low-speed test drive of your vehicle to verify the suspension’s performance before gradually increasing your speed to check for any persistent sounds.

6) Realign the Driveshaft

If the rattling sound in your vehicle originates from the middle or bottom of the frame and is accompanied by a vibration, it means that there is something wrong with the driveshaft alignment.  

• Employ a jack along with jack stands or ramps to lift the car.
• Get beneath your vehicle and pinpoint the driveshaft. It is recommended to consult the vehicle’s manual to easily locate the driveshaft.
• Unscrew the bolts that link the driveshaft to the differential and transmission, and remove it.
• Examine the driveshaft and identify the markings (either arrows or a dimple) that indicate how the driveshaft should be oriented. Otherwise, you may align the shaft by making sure that each half is arranged with the serial numbers facing the same way.
• Align the markings on both segments of the shaft.
• Reinstall the driveshaft by fastening the bolts in accordance with the manufacturer’s torque specifications.

7) Check Engine Oil and Pressure

Most vehicles come equipped with an alert light that signals when the engine oil pressure is insufficient. If this light illuminates, you should cease driving until the issue is addressed.

Additionally, assessing the engine oil level is important. If the oil appears to be contaminated, it’s recommended to replace it entirely and install a new filter.

Alternatively, if the oil is clean, topping off the system with some additional oil might be enough. However, if the oil level persistently falls, you might have an oil leak that requires fixing. If this leak is not visible, it may be internal, as is often the case with a blown head gasket.

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