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How To Fill A Torque Converter

Have you ever thought about what happens when you change the gear in your automatic transmission vehicle? This vehicle has a torque converter that transfers power from the engine to the transmission. The transmission then changes the gear of the engine. But how can you fill a torque converter? We asked the experts, and this is what we learned.

To fill a torque converter:

  1. Remove the torque converter from the transmission input shaft.
  2. Place the torque converter on a flat surface. Keep the large hole facing upward.
  3. Fill the converter with a fluid that is suitable for your car.
  4. Re-install the torque converter back to the transmission input shaft.

Keep reading as we discuss how you can drain and refill a torque converter. We will also explore signs to watch out for so you can tell whether your torque converter is failing and how you can test the torque converter.

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Automobile transmission gearbox in sections, How To Fill A Torque Converter

How To Drain And Refill A Torque Converter

An automatic transmission vehicle has a torque converter that functions similarly to a clutch in a manual transmission automobile. But it relies on a fluid to carry power to the transmission, keeping your engine from stalling and enabling the transmission to change.

Automatic transmission with torque converter is centrifugal pump and centripetal turbine

The torque converter's automatic transmission fluid (ATF) may gather dirt or deteriorate from exposure to the internal heat your car generates during regular operation. For this reason, it is vital to change the ATF every 30,000 miles.

The transmission fluid breaks down when you fail to change it, thus losing its lubricating properties. Consequently, your car's transmission may develop serious problems or die sooner than expected.

To avoid this, drain and refill the torque converter as soon as you reach the recommended mileage. Keep reading if you want to do this yourself rather than take the car to the shop.

Draining The Torque Converter

With a Drain Plug

Some car models have a drain plug in the torque converter, which lets you drain the old ATF when the engine is off. First, refer to your vehicle's manual to find out if your automobile has one, then do the following.

  1. Locate the torque converter. Ordinarily, you can find it in your car's undercarriage, between the engine flexplate and the transmission drain pan.
  2. Remove the access panel in the torque converter bell housing to reveal the drain bolt hollowed into the converter. Next, spin the crankshaft to position the hex nut opening at the bottom of the converter's rotation for easier access. 
  3. Unscrew the bolt to remove the drain plug, then let the ATF drain into a drain pan.
  4. Re-install and tighten the drain plug when there is no more fluid in the torque converter.

Without A Drain Plug

Most models do not have a drain plug. Therefore, you rely on your car's converter to pump out the fluid. Keep the engine running during this process to power the converter.

Since this method of draining requires that you drain and refill the ATF simultaneously, make a provision for extra quarts of the new ATF. You will also need one or two assistants to help you conduct the exercise seamlessly.

  1. Refer to your vehicle's user manual to access the transmission return cooling line. You may need to remove the engine's flexplate to access it.
  2. Assess whether the cooling line is flexible or rigid. Detach the pipe at the transmission if it is bendable or at the cooler if it is stiff.
  3. Fix a pipe to the cooling line and route it to a bucket or drain pan sizeable enough to hold the contents of the torque converter. Strategically position the bucket to see the fluid draining into it. Do this while the transmission is in neutral gear.
  4. Ask one of the assistants to start the engine while you observe the fluid coming from the hose. The other assistant can slowly add the fresh ATF while allowing enough time to drain the old one. The first assistant can set the car in 'drive' gear whilst engaging the parking brake to circulate the fluid in the torque converter and retain the transmission in 'park'.
  5. Observe for fresh fluid flowing from the drain hose - when new ATF drains from the tube, you will have exhausted all the old ATF.
  6. Switch off the engine and re-fix the cooler line. 

Refilling A Torque Converter

Automobile transmission part

Most models require that you remove the torque converter from the vehicle before filling it. But if your automobile has a lock-up torque converter or a torque converter that has a drain pan, you can refill it without removing it from the vehicle.

  1. Use both hands to hold the torque converter, then apply a little pressure to turn it counterclockwise. 
  2. Listen for a click sound; the click implies its release from the transmission input shaft, thus allowing it to slide off.
  3. Set the torque converter on level ground with the large opening in the converter hub facing upwards. 
  4. Carefully fill the torque converter with an ATF befitting your car. Add as much fluid as you can to ensure that it doesn't dry out when you start the engine. You can wiggle the torque converter slightly to create more room for the fluid.
  5. Slide the torque converter onto the transmission input shaft. Do this as quickly as possible to reduce spillage.
  6. Rotate the converter clockwise while listening for a click sound to ascertain that it is firmly held in place.

How To Identify A Failing Torque Converter

Your car's torque converter can malfunction, threatening your safety and that of other road users. Because it is a common transmission problem, it is necessary to know what to look out for to identify a failing torque converter. 

Transmission is Overheating

Excess ATF can exert too much pressure within the transmission, causing it to overheat. At other times, low or old transmission fluid can cause heating up due to the fluid's reduced lubricating properties. The friction between the transmission's components generates heat in such instances.

Leaking Transmission Fluid

Oil leaks or drops from the car's engine on the parking lot

Regular car operation can wear out or damage the torque converter seals, resulting in fluid leaks. Promptly take action if you notice that the ATF is spilling to avoid causing significant internal damage to your vehicle.

Loss Of Acceleration

The transmission fluid in the torque converter helps move power generated by the engine to the transmission. The transmission then changes the engine's gear, thus transferring this power to the wheels, causing the vehicle to accelerate. 

Your car may fail to gain speed when the torque converter is defective since the power generated is not transferred efficiently. At other times, the vehicle may vibrate when you exert pressure on the gas pedal.

Slipping Between Gears

Gears can slip if too much or too little fluid flows through the car's system. If the transmission filter is clogged, it can alter the quantity of the oil that flows through, causing the gears to slip. Thus, you should be concerned if the gears do not shift smoothly as the torque converter may be malfunctioning. 

Vehicle Fails To Shift Gears

If the torque converter is defective, your car may fail to engage a specific gear, say forward drive or reverse. Here, the automobile fails to engage the transmission, which is responsible for shifting the gears.

How To Test A Torque Converter

You can test whether your torque converter is defective by conducting a stall-speed test. But it is wise to check with your car's manufacturer whether this check is suitable for your vehicle. The stall-speed test can damage both newer and older transmissions.

You cannot carry out this test on a vehicle with traction control or an anti-lock brake system. Furthermore, the test will activate the check engine light in an automobile with an electronically controlled transmission.

1. Prepare The Vehicle

Check that all the fluids in your car are in perfect condition. Then chock the vehicle's wheels and set it on 'park' to avoid accidental movement. Buy a tachometer if the automobile does not have one. The tachometer aids in calculating the number of revolutions per minute. It can be manual or automatic.

2. Start The Engine

Man starting the car

Push the brake pedal to the floor, start the engine, and set the transmission to drive. Keep your foot pressed on the brake pedal.

3. Press The Accelerator

Accelerator and breaking pedal in a car

Keeping one foot on the accelerator, use the other foot to push the accelerator all the way for two to three seconds. Ensure that you do not hold for more than five seconds to avoid blowing the transmission.

Check the RPM (Revolutions Per Minute) that the engine maxes out. This reading is your car's stall speed. 

4. Interpret The Readings

Compare the RPM readings you obtain with your car's torque converter and engine specifications. If the reading is lower or unusually high, you may need to investigate further and repair or replace it. Higher readings often imply a slip in the transmission, while lower readings indicate a damaged converter.

In Closing

You rely heavily on the proper working of a torque converter for the efficient running of your car if you have an automatic transmission vehicle. Therefore, it is necessary to occasionally remove the old ATF and replace it with fresh fluid to maintain your vehicle in good condition.

We hope the information provided in this article will guide you if you would like to drain and refill the torque converter. We also hope that you will be able to catch any malfunction before it develops into a bigger problem.

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