ALT-1 How to Change Automatic Transmission Fluid Atf
A car's transmission (or transaxle as they are sometimes called in front-wheel drive vehicles) needs regular fluid maintenance just as the engine's fluid systems require attention.
There are some unique aspects to changing the fluid that must be considered before even turning a wrench.
It all begins in your owner's manual. There you must find the correct type of transmission fluid for your car. If you fail to stick to the guidelines and use fluid incompatible, the end result may be major damage. Some fluids may damage seals and other components in the transmission if they were not made for it.
A $20-$40 fluid change could end up costing so much more just because the proper fluid was not used. Fords may take a different type of fluid than Dodge/Chrysler, etc.
Know your car, is the transmission a 3-speed with overdrive? A 4-speed without overdrive? Why is this important? When you change the fluid you must also replace the filter that is mounted on the bottom of the transmission just inside the oil pan. Different configurations have different filters. You will not be able to do a visual comparison until you have the fluid out, the pan off, and then finding you have the wrong filter can get ugly very fast.
Do not leave your keys inside the car when changing the fluid.
Block the tires with sturdy blocks to prevent rolling when raising the car to gain access to the transmission. Set the parking brake, but be aware that parking brakes do not work in reverse. This means if you jack your car on an incline facing uphill, the parking brake will not prevent the car from rolling backwards (drum brakes on the back).
Back you car up the hill will offer more protection from this problem prior to starting.
Before loosening bolts, place a pan to collect the fluid under the transmission. Fluid can come out anywhere the pan is bolted to the housing.
There is no drain valve/plug on automatic transmissions. The only way to get the fluid out is to loosen the bolts holding the pan to the bottom of the transmission casing. It is best to start at the lowest corner and loosen bolts a little at a time working around the pan's circumference.
NEVER use the engine in operation to drain the fluid, it will drain faster than you can get to the ignition running the system dry. This drains the fluid in the torque converter as well. While all of the fluid will not be changed in a change cycle, if the fluid is exremely dirty, multiple changes should be considered over operating the engine to drain the fluid. This method can result in damages that will not be covered by manufacturer's warranty. Fluid levels for changes are also based on a gravity drain of the pan, not emptying the torque converter and running the system dry. It cannot be stressed enough to follow the manual for your car to avoid costly mistakes.
Even then, you may not get fluid to flow. Heat from use may bind the transmission pan to the casing. It is important to be very careful when breaking this seal. LEAVE ALL THE BOLTS IN but loosened. This will prevent it from dropping and spilling the sump contents.
Using a flat scraper is better than screwdrivers for prying the two apart. Many transmission casings are made of aluminum and screwdrivers are steel or other harder metal. If you gouge the sealing surface of the transmission housing, you will have difficulties getting it sealed again when reinstalling the pan later.
Slide a thin putty knife (preferably the plastic type) between the bolts and use it to break the contact between the pan and the transmission housing.
Start at the low end and work your way around. When the pan breaks free, the bolts will hold it up. This works best for you because you shouldn't get sprayed with fluid.
Once the fluid starts flowing, verify your collection pan is able to get all of the fluid contained. If not, tighten some of the bolts higher up to force it out the lower end.
When the fluid stops flowing, resume loosening bolts at the lowest end first and working around. Eventually the bolts will be loose enough to remove. It is best to remove all but the corner bolts.
When ready, place one hand under the pan to hold it up and remove the remaining bolts. Remember there is still going to be residual fluid in the pan. Hold it level and lower it to the collection container. Dump the remaining fluid into the container.
Look inside the pan. You should see in the lowest section a mass of black. This will be where the magnet is located. Transmissions typically have a magnet affixed to the bottom in the pan to allow metal particles to be held in the pan preventing circulation.
The magnet should only be held by the magnetic properties. Pry the magnet out and examine the debris held to it. Small particulate debris is expected. If there are larger pieces, consider professional intervention to ensure all is well.
Wipe the magnet clean using a lint-free rag. Lint free means it does not leave particles behind. Failure to use a lint free rag can contaminate your oil system with cloth particles which can restrict oil flow. Shop rags are available that are lint-free. Read the packaging to ensure they are.
Wipe the pan clean, also with lint free rags. Inspect the gasket sealing surface. It should be clean, smooth (no gasket material left) and dry. If there is gasket material still stuck to it, carefully remove it so as to not damage the sealing surface. Wire brush or scrape with a sharp blade works well. Replace the magnet back where it was removed from and dry the sealing surface before setting the pan aside.
There will be one or more bolts that hold the filter in place. BEFORE removing the filter, remove the new filter from the box and compare it to the filter installed. If they do not match it is best to not remove the old filter. It is still keeping contaminants from entering the transmission passages.
If the filter is correct, remove the bolts holding it and lower it from the transmission casing. Verify if there are any O-ring seals and if they were left in the housing. Verify if there was a gasket between the filter and housing and if so ensure it also came off with the filter or remove it separately. Leaving it is never good.
Inspect the new filter, verify there is no damage to sealing surfaces, verify it has not been crushed and has no visible damage. (Stores and/or shippers can drop and damage filters before they even reach your hands.)
If the filter is in good condition, verify if there was a gasket or O-ring and install it if required. Typically if you remove one there should be a new one to take the place of the old when performing this.
Place the new filter up and insert the bolts. Follow torque specifications when reinstalling a filter. The housing is aluminum. Too tight and you could strip the threads. Too loose and you will short cycle the fluid system causing your transmission to malfunction.
The technical manual for the car should give proper torque specs. Use a good-condition torque wrench - not one that has been dropped, left in water, etc.
Once the new filter is snuggly in place to proper torques, inspect the bottom of the housing. Ensure there is nothing that can cause damage. No pieces of cloth clinging to surfaces, etc. Also inspect the sealing surface on the bottom of the housing. Ensure all old gasket material and any sealant that may have been used is cleaned off. Inspect for damage to the surfaces. Surface damage may be a source of a leak when you are finished.
Verify the oil pan is clean, dry and the magnet is in place. Fit the new gasket on the oil pan. Put bolts through the holes in the corners, this helps hold the gasket in alignment.
Lift the pan up, but do not press against the housing (it will make the bolts fall out). Start the corner bolts holding the gasket only a few threads, then insert the remaining bolts. This ensures all of the holes are aligned before beginning tightening.
Tighten the bolts in a cross pattern or following the tightening sequence in the manual. Draw them all snug to the pan before tightening any fully.
Again, use the correct torque specifications to ensure the bolts are not left too loose or overtightened.
If jacks and/or jack stands were used for this, now is the time to remove them.
Fill the transmission to the recommended level after replacing the filter, with the correct type of automatic transmission fluid. Start the car and verify the fluid level is correct. If not, add fluid until it is the correct level. Do NOT overfill the transmissioin.
Inspect the oil pan sealing surface. Verify there are no leaks. If jacks and/or jack stands were used,Let the car run a few minutes to warm up, then cycle the transmission through the gears (keep your foot on the brake and the parking brake engaged for safety).
Place the car in park and visually inspect the gasket surfaces again to ensure there are no leaks. Leaks will lower the level of fluid in your car (costing money to maintain the correct fluid level over time) while harming the environment and making road surfaces just a bit slippery, particularly when rain first begins falling.
That is it! You have successfully completed the job of replacing the transmission fluid and the filter on your vehicle.
