Automatic Transmission Have Grinding Noise When Put in Gear. How To Fix?

Automatic transmissions are impressive pieces of machinery. They can change gears smoothly and effortlessly, making it possible for drivers to focus on the road ahead. However, automatic transmissions sometimes encounter problems that make them produce grinding noise when put in gear.

Automatic transmission grinding noise when put in gear results from low transmission fluid, clogged filters, damaged synchronizers, and gears, or worn-out torque converters and transmission pumps. Easy fixes include topping up the fluid, cleaning dirty components, and replacing damaged parts.

The rest of this article will describe these and more causes of automatic transmission grinding noise in detail. Read on for more information on how to fix each potential cause of this problem.

Causes of Automatic Transmission Grinding Noise

In a nutshell, automatic transmissions can produce a grinding noise when put in gear for various reasons. These often range from neglecting simple maintenance guidelines to more severe damage that may require replacing entire components.

The following are some of the most common causes of grinding noise when an automatic transmission is put in gear.

Low Transmission Fluid

The transmission fluid is the lifeblood of your automatic transmission, as it keeps the internal components lubricated, cooled, and functioning correctly. When the transmission fluid level is low, it can cause the gearbox to overheat. This damages the gears and other internal components, leading to a grinding noise when the car is put into gear.

Read: Why Speedometer Is Not Working and Transmission Is Not Shifting?

The Transmission Filter Is Clogged

The transmission filter keeps the fluid clean and clear of debris, but when it becomes clogged, the flow of fluid is restricted. This can lead to overheating and damage to the gears, leading to a grinding noise when the car is put into gear.

Some of the tell-tell signs that your transmission filter is clogged include:

The transmission fluid discolors from bright red or pink to brown or a darker color.
The transmission fluid has a burnt smell.
The car struggles to move forward or reverse when the transmission is put into gear.

The Synchronizers Are Worn Out or Damaged

Synchronizers ensure the transmission fluid is delivered evenly to each gear. When they become worn-out or damaged, they can’t properly synchronize the gears, and as a result, the gears grind against each other, causing a grinding noise when the car is put into gear.

Read: Why Your Car’s Transmission is Slipping & Fix

The Gears Are Bent or Damaged

The gears play a critical role in the smooth functioning of an automatic transmission. According to AAMCO, when these components are bent or damaged, the transmission may grind when put into gear. This often results from an accident, but it can also be due to wear and tear.

Some of the signs of gear damage include:

Grinding noises when the transmission is put into gear.
The car jerks or shudders when it’s in gear.
Difficulty shifting gears.
The transmission slips when accelerating.

The Torque Converter Is Damaged

The torque converter is responsible for transferring power from the engine to the transmission. When it becomes damaged, it can’t do its job correctly.

As a result, the car may struggle to move when the transmission is put into gear, leading to a grinding noise. Also, a damaged torque converter can cause the vehicle to stall out when the transmission is put into gear.

Read: Why is My Car With Automatic Transmission Jerking?

The Transmission Pump Is Worn Out

The transmission pump helps circulate the transmission fluid throughout the gearbox. However, like any other component in your car, this part will eventually wear out and need to be replaced. When this happens, it can’t deliver the correct amount of fluid to the transmission, leading to overheating and damage.

The grinding noise is often the first sign that the transmission pump is worn-out. Other symptoms of a damaged pump include:

The transmission fluid is abnormally black or thick.
The car has trouble accelerating.
There’s a leak in the transmission line.

The Valve Body Is Damaged or Dirty

The valve body is a critical component in the automatic transmission, as it regulates the flow of fluid and keeps the gears synchronized.

However, when it becomes damaged or dirty, it can’t do its job correctly. This can lead to several problems, including overheating, fluid leakage, and a grinding noise when the car is put into gear.

The Transmission Mounts Are Worn Out

The transmission mounts secure the transmission system in place. When they wear out, they can’t do their job properly, which can lead to the transmission moving around excessively, damaging the gears.

As a result, you may hear a grinding noise when the car is put into gear, especially when you start driving.

Caution: Any of these problems can cause a grinding noise when you put your car into gear. If you’re experiencing this problem, make sure to take it to a mechanic to get it fixed. If you don’t address it, the damage could get worse and lead to even more severe problems with your car.

Read: Car Diagnosis Cost

8 Ways To Fix Automatic Transmission Grinding Noise

If you hear grinding noise when you put your automatic transmission in gear, one or more of the problems listed above may have caused it. So, how do you solve these problems?

Let’s take a look at a few steps to follow to address each of the possible causes of automatic transmission grinding noise.

1. Top Up or Replace the Transmission Fluid

If the transmission fluid is low, topping it up can often fix the grinding noise. But if the fluid is dirty or contains burnt particles, you should replace it with a new batch of fluid.

To top up or replace the transmission fluid, you’ll need to:

Open the engine cover.
Locate the transmission fluid dipstick.
Remove the dipstick and wipe it clean.
Reinsert the dipstick and check the level of fluid.
Add more fluid, if necessary, until the level reaches the “full” mark.
If the fluid is contaminated, drain it and refill the transmission with fresh fluid.
Close the engine cover.

2. Clean the Transmission Filter

If the transmission filter is clogged, cleaning it can help to eliminate the grinding noise. To clean the filter, you’ll need to:

Open the engine cover.
Locate the transmission filter. You’ll find it right above the transmission pan.
Remove the filter and clean it using a degreaser or solvent.
Rinse the filter with clean water.
Secure the filter back in place.
Close the engine cover.

3. Replace the Synchronizers

If you think the synchronizers are at fault, you can replace them by following these steps:

Remove the transmission pan.
Disassemble the transmission.
Locate the synchronizers.
Remove the synchronizers using a pair of pliers or a wrench.
Install the new synchronizers.
Reassemble the transmission.
Refill the transmission with fresh fluid.

Caveat: You need mechanical knowledge and experience to correctly disassemble and reassemble the transmission. If you’re not comfortable doing this yourself, take your car to a mechanic. However, arm yourself with a shop manual if you prefer the DIY route.

Read: Car Full Service Cost // Whats included?

4. Replace the Gears

If the gears are bent or damaged, replacing them is your best bet for eliminating the grinding noise. To replace the transmission gears, you’ll need to:

Remove the transmission cover.
Disassemble the transmission.
Remove the gears.
Replace the gears.
Reinstall the transmission cover.

Note: Ensure you have the proper tools and knowledge before replacing the gears yourself.

5. Replace the Torque Converter

If a damaged torque converter is the cause of the grinding noise, replacing it should solve the problem. To replace the torque converter, you’ll need to:

Open the engine cover
Remove the transmission pan.
Disassemble the transmission
Remove the torque converter.
Install the new torque converter.

Here’s a YouTube demo of how to remove a torque converter from a disassembled transmission:

Caveat: Replacing the torque converter requires some mechanical knowledge and experience. If you’re not comfortable doing this yourself, take your car to a mechanic.

6. Replace the Transmission Pump

If the transmission pump is worn-out, replacing it can help fix the grinding noise. To replace the transmission pump, you’ll need to:

Open the engine cover.
Locate the transmission pump.
Remove the pump and replace it with a new one.
Reinstall the pump.
Close the engine cover.

7. Clean or Replace the Valve Body

If the valve body is dirty or damaged, cleaning or replacing it can help to eliminate the grinding noise. To clean or replace the valve body, you’ll need to:

Open the engine cover.
Locate the valve body.
Remove the valve body and clean it using a degreaser or solvent.
Rinse the valve body with clean water.
Reinstall the valve body. Replace the current valve body if you spot signs of damage.
Close the engine cover.

8. Replace the Transmission Mounts

If the transmission mounts are worn-out, replacing them can help fix the grinding noise. To replace the transmission mounts, you’ll need to:

Jack up the car and remove the wheel on the side of the transmission.
Remove the bolts that hold the transmission mount to the car’s frame.
Install a new transmission mount and reinstall the bolts.
Lower the car.

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