Automatic Transmission Clunks When Stopping (Here Is Why)

automatic transmission clunks when stopping

Automatic transmission clunks when stopping can be quite worrisome for car owners. This clunking noise may be indicative of an underlying issue that needs attention. In this article, we will explore the common causes of transmission clunks, how to diagnose them, and how to address these issues to keep your vehicle running smoothly and safely.

1. Causes of Transmission Clunks

There are several reasons why your transmission may make clunking noises when coming to a stop. Some common causes include:

A. Low or Contaminated Transmission Fluid

Transmission fluid is vital for providing sufficient lubrication and allowing smooth gear shifting. If the fluid level is too low or the fluid is old, contaminated, or burnt, proper cooling and lubrication become difficult. Checking the fluid level and appearance can help identify if this is the problem.

B. Faulty Sensors or Computerized Controls

Many modern cars have transmissions controlled by computerized sensors. Clunking noises can occur if these sensors send incorrect shifting or speed information, causing problems due to improper regulation. This issue should be inspected by a professional.

C. Internal Component Problems

The transmission houses various components like springs, gears, and bearings that contribute to proper gear shifting. Problems with any of these components can result in clunking noises. In such cases, the transmission must be removed for accurate diagnosis.

D. Loose or Broken Transmission or Engine Mounts

If the transmission or engine mount becomes loose or breaks, clunking noises may be heard when changing speed or shifting gears, due to the movement of the unsecured mount. A mechanic can determine if this is the issue by inspecting the parts that hold the transmission or engine in place.

E. Universal Joint Issues

Sometimes, the clunking noise you think is coming from your transmission may actually be caused by malfunctioning universal joints.

Read also >> Automatic Transmission Problems and Solutions (Easy Fix)

Read also >> Automatic Transmission Problems Shifting Gears (Solved!)

Read also >> Limp Mode in Automatic Transmission (Causes and Solutions)

Read also >> Automatic Transmission Slipping When Accelerating (SOLVED!)

2. Diagnosing Transmission Clunks

To determine the cause of transmission clunks when stopping, follow these steps:

Step 1: Identify the Source of the Noise

Determining the general area the clunking noise is coming from can help you pinpoint the problem. Listen for whether the noise comes from the front, back, left, or right side of the vehicle.

Step 2: Check Engine and Transmission While Stopped

If the clunking continues even when the vehicle is stationary, the problem may lie with the engine or transmission. In this case, seek professional help for repairs.

Step 3: Test Drive at Various Speeds

If the noise only occurs at specific speeds, try driving at that speed in different gears. If the sound stops, the problem may be with the transmission. Consult a certified professional for assistance.

Step 4: Inspect Tires

Worn or damaged tires can cause strange noises while driving. Check for cup-shaped wear patterns or excessively worn tread, which may indicate issues with shocks or springs.

Step 5: Drive Over a Bump

If you hear a clunking noise when going over bumps, your shock absorbers could be wearing out, or there may be an issue with ball joints.

3. Addressing Transmission Clunks

Once you’ve identified the cause of the clunking noise, it’s crucial to address the issue promptly to prevent further damage or safety concerns.

A. Transmission Fluid Maintenance

If low or contaminated transmission fluid is the culprit, you may benefit from a transmission flush service. This process involves draining the old fluid, cleaning the system, and refilling it with fresh fluid.

B. Sensor and Computerized Control Repairs

If faulty sensors or computerized controls are causing clunking noises, a professional mechanic should be consulted for diagnostic testing and repairs.

C. Internal Component Repairs

For problems with internal transmission components, removal and inspection of the transmission are necessary. A professional mechanic will be able to identify and repair the issue.

D. Transmission and Engine Mount Repairs

If loose or broken transmission or engine mounts are causing clunking noises, a mechanic can replace or repair these mounts to secure the transmission and engine in place.

E. Universal Joint Repairs

If the clunking noise is due to malfunctioning universal joints, a mechanic can inspect and replace these parts as needed.

4. Preventive Measures

To avoid clunking noises and other transmission issues, it’s essential to practice proper maintenance and care for your vehicle. Some preventive measures include:

A. Regularly Check and Change Transmission Fluid

Check your transmission fluid levels and quality at least once a year, or as per your vehicle manufacturer’s recommendations. Replace the fluid if it’s low, contaminated, or burnt.

B. Keep Sensors and Computerized Controls in Good Condition

Ensure that your vehicle’s sensors and computerized controls are functioning correctly. Consult a professional mechanic for regular checkups and necessary repairs.

C. Inspect Transmission and Engine Mounts

Regularly inspect the transmission and engine mounts for signs of wear or damage. Replace or repair them as needed to keep your vehicle running smoothly and safely.

D. Monitor Tire Condition

Check your tires regularly for signs of wear or damage. Replace them if the tread depth is 2/32 of an inch or less, or if they show signs of cupping due to worn shocks or springs.

E. Regularly Inspect Suspension Components

Examine your vehicle’s suspension components, including shock absorbers and ball joints, for signs of wear or damage. Replace or repair them as necessary to maintain proper vehicle handling and safety.

Is it safe to drive with clunking noise?

Driving with a clunking noise can be unsafe and it is recommended to get it checked as soon as possible to avoid further damage and costly repairs.

Unusual noises like clunking, humming, and grinding could indicate transmission problems, and it is important to diagnose the cause of the noise by checking fluid levels and examining the clutch assembly for issues.

However, low transmission fluid levels can also cause clunking noises, and driving with low fluid can cause permanent damage to the transmission. Therefore, it is best to seek the help of a certified transmission specialist and avoid driving with a clunking noise for an extended period of time.

Why does my car make a clunking noise when idling?

Clunking noise in a car when idling can be caused by various issues, including problems with the transmission. If the transmission fluid is low or old, it could cause clunking noises and permanent damage to the transmission.

Faulty internal components, loose or broken transmission or engine mounts, or issues with transmission sensors can also cause clunking noises. Another possible cause of clunking noises is a faulty engine or transmission mount, which can cause the engine or transmission to clunk against the frame.

Loose exhaust system clamps or a failing catalytic converter can also cause rattling noises under the car.

why does my automatic gearbox clunk?

Your automatic gearbox may be making a clunking noise due to a variety of reasons. These may include transmission problems, low or old transmission fluid, issues with sensors in the transmission, faulty internal components, broken or lose transmission or engine mounts, and malfunctioning universal joints.

If the clunking noise occurs when idling, it could be due to faulty internal components, loose engine or transmission mounts, or broken transmission mounts. It is not safe to drive with a clunking noise, as it may lead to permanent damage and costly repairs.

5. Conclusion

In conclusion, paying attention to clunking noises from your automatic transmission when stopping is crucial for maintaining your vehicle’s performance and safety.

By diagnosing and addressing the issue, you can prevent further damage and ensure a smooth, safe driving experience.

Steve P.

Steve is an automotive technician, technical writer, and Managing Editor. He has held a lifelong passion for cars, with a particular interest in cars like the Buick Riviera. Steve is based in Boise, Idaho.

Recent Posts

error: Content is protected !!