How to Remove the Front Seal From an Automatic Transmission

by Jessica Danson
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transmission image by Philippe SURMELY from

An automatic transmission helps to ensure your vehicle runs correctly. The automatic transmission keeps the driver from having to shift gears by hand and will do this for you automatically. Its main purpose is to deliver power to the wheels so that the automobile can move. One of its main components is the seals and gaskets that control the flow of hydraulic fluid and keeps it from leaking out onto other parts of the engine. When this happens the front seal must be replaced.

Step 1

Raise the front of the car to begin the repair process with the use of a car jack. To do this, slide the jack under the differential and lift the vehicle off the ground. Unlock the ignition and place the gearshift in neutral. Do not start the engine.

Step 2

Locate the front seal and remove everything that prevents your access to it. Start with the belt which can be removed by loosening the belt tension that holds it. Move on to the harmonic balancer bolt and unscrew with the use of a wrench. Once unscrewed, pull off the balancer by hand. If the transmission has a key, take that out as well but keep it in a safe place as you will need to put it back once you start reinstalling everything.

Step 3

Use a screwdriver to pry out the driveshaft. With the duct tape, secure the universal caps so that they don't fall onto the driveshaft. Place the drain pan under to catch the oil that will spill out. It is now safe and easy to pull off the old seal. Make sure not to damage the crank shaft. Clean the front seal with your rag. Do the same to the seal surface to ensure that the front seal slides back easily onto it when you reinstall.

Step 4

Rub a bit of engine oil onto the outside edge of your seal. With the socket wrench or the screwdriver handle, tap the seal back into place. Make sure that the seal sits squarely on the shaft's surface.

Step 5

Reinstall the key next. To do so, you will need to put some silicone sealant onto the key-way to hold the key in place. You are now ready to place the key back onto the key-way.

Step 6

Apply a small amount of clean engine oil around the lip of the seal to help the balancer slide on easily. Slide the balancer in using your bare hands. Make sure not to tear any part of the balancer when you slide it in. Align it carefully with the key-way slot before you bolt it back on. Re-install the belt by tightening the tension. When the tension is tight, the job is finished.

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