To install a new crankshaft front oil seal, loosen the alternator to slacken the drive belt. Remove the belt along with radiator if these items block access to the seal. If the car has a manual transmission, set it on first or reverse, and raise the handbrake to its tightest position to keep the vehicle stationary. If the car is an automatic, detach the battery terminals, and remove the starter motor.
Insert a wrench or screwdriver into the starter opening to keep the flywheel from moving, then loosen the pulley bolt using a socket and bar combination. Apply as much sharp force as necessary. The pulley bolt rotates counter clockwise on a clockwise turning engine and vice versa. Once loosened, the pulley may be pulled off easily or require the use of a universal puller.
There's a key between the pulley and crankshaft that prevents the pulley from turning along with the crankshaft. Remove this key, and secure it for later.
Clean the area around the oil seal thoroughly, and confirm that you can see the seal's outer end. If not, remove the timing chain or timing belt cover. Include the water pump if necessary. If the engine has a belt-driven overhead camshaft, remove the belt and drive sprocket.
Use a flat screwdriver to pry the oil seal out, making sure not to scratch the seal housing. Wipe off the housing with clean rags, and push the new seal in with the open side facing the engine. To ensure the seal and housing are perfectly aligned, place an object with a solid flat surface such as a wooden block over the seal, then tap the block gently with a mallet to push the oil seal into place. Reverse the removal process to complete the oil seal installation.