How to Change Transmission Fluid Without Removing the Panby John Yarbrough
A transmission transfers rotational motion from the engine to the wheels that move the vehicle. At regular service intervals, typically between 12,000 and 30,000 miles, transmission fluid must be changed to keep the gears shifting smoothly. Performing a transmission fluid change requires a little more precision than changing motor oil. But, if you know how to remove a drain plug, then you should be able to change transmission fluid without removing the pan. However, understand that this method will only allow you to change about 25 percent of the fluid.
Start and run the engine. This is a good opportunity to pick up any supplies you may not have on hand. Let the engine and transmission run for at least 5 minutes to bring the transmission fluid to its normal operating temperature.
Park and secure the vehicle. Turn off the engine and immobilize the vehicle so it will remain stationary while being serviced. Use wheel chocks both in front of and behind at least one of the wheels.
Place the bucket under the transmission drain pan. Position the larger bucket underneath the drain plug.
Carefully remove the drain plug using a socket wrench with the appropriate socket. Allow the transmission fluid to drain freely into the bucket until slowed to a drip.
Replace the crush washer. Remove the old crush washer from the drain plug by twisting it free. Some crush washers are stubborn, so you might have to carefully nib away at the washer with diagonal-cutting pliers and then twist it free with needle-nose pliers. If there is a crush washer to replace, twist it on to the drain plug threads until it reaches the head of the plug. The flat bottom of the washer should be butting against the head of the drain plug.
Replace the drain plug. Carefully thread the drain plug back into the pan and hand-tighten with the socket wrench. Transfer the socket to the torque wrench. Torque the drain plug to the torque specified in the vehicle's service manual.
Locate and open transmission fluid filler. Typically, this is also the location of the transmission dipstick.
Pour in fresh transmission fluid. This step is crucial and requires attention to precision. Carefully pour the drained fluid into the 1-quart paint pail until you have reached the 1-quart mark. Remove the transmission dipstick and insert the funnel. Pour that same amount of fresh transmission fluid into the transmission filler. One quart of the old transmission fluid can now go into the now-empty quart bottle to later take to a recycling center. Repeat this process until exactly the same amount of new transmission fluid has replaced the old fluid. Periodically reinsert the dipstick to check the level and ensure you are pouring in enough fluid.
Start the engine and allow the transmission to run. Run the vehicle through all the gears. Stop the engine and check the dipstick again. If the fluid level is low, gradually add more transmission fluid. Repeat this process until the fluid level is in the acceptable range.
- Purchasing more transmission fluid than you need is better than not buying enough.
- Many parts stores will recycle your used transmission fluid free of charge.
- If the transmission fluid has a burn smell to it, you may need to have the transmission examined by a professional transmission service technician.
Things You'll Need
- Transmission fluid
- Vehicle-specific service guide
- Wheel chocks
- Socket wrench and sockets
- Torque wrench
- 1-quart painter's touch-up pail with ounce volume graduations
- Crush washer
- Only use transmission fluid that is compatible with the transmission you are servicing—the wrong amount and wrong type can ruin the mechanism.
- Some manufacturers do not recommend a flush and fill of transmission fluid.
John Yarbrough has been a freelance writer since 2009. He has published online works on eHow with an emphasis on electronics, home improvement and other technical subjects. He holds a Bachelor of Science in electrical engineering and a Master of Science in engineering from Virginia Commonwealth University.