Changing Automatic Transmission Oil and Filter
Changing the fluid in the
automatic transmission
in your vehicle promotes proper operation and helps the transmission last longer
without failure. All car manufacturers have different service intervals for their
particular transmission. In a typical transmission service, the fluid is completely
flushed (including the torque converter),
a filter is changed, the transmission pan is cleaned and a new pan gasket installed.
When refilling, use manufacturer specified fluids.
Step 1 - Replacement Parts (service kit) and Transmission Fluid
Tools and Parts Needed for a Transmission Service
Start with proper tools; transmission fluid and transmission filter service kit.
The service kit includes a transmission filter with seal and pan gasket. All transmission
fluid varies from car to car. Consult your vehicle's owner's manual for your particular
type of transmission fluid.
Step 2 - Identify Transmission Components
Automatic Transmission Pan
Most automatic transmissions
have a service pan that houses the transmission fluid and filter. This transmission
has a heat shield to keep heat from the exhaust away from the transmission. Some
transmission pans have a fluid drain plug used to drain the fluid.
Step 3 - Drain Transmission Fluid
Locate Drain Plug
Insert drain plug removal tool and turn counter clockwise. Loosen the drain plug
until easily removed by hand. Some transmissions do not have a drain plug. In this
case the fluid will exit when the transmission pan is removed.
Step 4 - Drain Transmission Fluid
Remove Drain Plug
After the drain plug is loosened, remove plug to drain transmission fluid into
oil catch pan then allow to drain until completely empty.
Step 5 - Remove Transmission Pan
Remove Pan Bolts
When the fluid is finished draining, remove transmission pan mounting bolts.
Remove all but two bolts to hold pan in place.
Step 6 - Removing Transmission Pan
Lowering Transmission Pan
When all but two bolts remain, place your hand under the transmission pan and
remove the remaining bolts. Gently lower the pan from the car. You may have to move
a heatshield or gear selector cable mount to remove the pan.
Step 7 - Checking the Pan for Metal Debris
Inspecting Transmission Pan for Metal Chips and Clutch Material
When the fluid pan is removed, inspect the pan for metal debris. All transmissions
have some metal in the pan but excessive metal can mean you may have a more serious
problems. The transmission in our example is very well maintained and has little
metal in the pan. Some transmission pans have a particle magnet that traps metal
and keeps it away from moving internal parts.
Step 8 - Clean Transmission Pan
Installing Transmission Pan Gasket
Fit Gasket
Before fitting your new gasket to the transmission pan, clean the pan magnet
completely. Some gaskets are manufactured with gasket sealer built right in like
the one in the diagram above. If your gasket is made of cork or some other style
of gasket, you will need a gasket fastening cement before you can install the gasket.
Step 9 - Changing Transmission Filter
Removing Used Transmission Filter
Most automatic transmissions have a filter that is located in the transmission
pan. Some filters are secured to the transmission with bolts or clips. The transmission
filter in this photo is held in by an o-ring seal at the front of the filter. Grasp
the transmission filter firmly and twist to remove, fluid will be present
in the filter.
Step 10 - Identify Internal Transmission Parts
Cleaning Gasket Surface
Before re-installing transmission pan; clean the gasket sealing surface with
a shop towel. This enables a secure seal to the new gasket when the pan is reinstalled.
While the transmission pan is removed you can inspect the electrical connection
to the shift control solenoids. The control solenoids determine what gear the transmission
is operating in and are housed in the valve body. All electrical connectors inside
the transmission should be secure for a good electrical connection.
Step 11 - Re-install New Transmission Filter
Installing New Transmission Fluid Filter
Always replace the seal for the transmission filter. As with most seals, it is
important that this seal does not leak. If the transmission filter seal leaks it
can cause the transmission to ingest air causing low transmission hydraulic pressure.
This causes the clutch disc's to slip and can cause premature failure. Re-install
filter in its proper location, re-bolt or re-clip as needed.
Step 12 - Re-Install Pan
Re-Installing Automatic Transmission Pan
Carefully reinstall the transmission pan, do not damage the gasket on reassembly
or transmission fluid could leak. Reinstall bolt and tighten them in sequence one
away from the other and continue until all pan bolts are snug. (Note: do not over
tighten, pan gasket could flatten out and leak)
Step 13 - Remove Transmission Fluid Level Check
Locate and Remove Automatic Transmission Level Dip Stick
Locate and remove the transmission fluid level checker, in most cars and trucks
this is where the fluid is checked
and added.
Step 14 - Refilling Transmission Fluid
Adding Transmission Fluid Using a Funnel
Insert fluid funnel and add transmission fluid until the proper amount of fluid
level is reached. Allow the engine
to warm and recheck the fluid level, add fluid as needed. Do not over fill the transmission,
it could foam the fluid and cause low fluid pressure causing premature transmission
failure. Recheck transmission for leaks and recheck fluid level in a couple of days.
Common Problems
- Premature transmission failure due to lack of maintenance, low fluid, dirty
filter.
- Manual transmission: premature clutch failure due to abusive driving habits.
If further assistance is needed, our certified car repair technicians are ready
to answer your car questions. Also, gain manufacturer
specific instructions and information by clicking -
Auto Repair Manual
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