I got the opportunity to be in part with the technicians to replace the new flywheel oil seal. The main issue is flywheel oil seal is damaged and crack. If the seal is damaged, the constant bath of oil combined with the spinning motion of the crankshaft will cause a rear main seal leak and allow a significant amount of oil to leak from the engine as it is running.
Remove all the attached screws and set them away in a small box or container to ensure that they are not lost. Carefully lift down the gearbox by using a jack stand.
Figure 36: Gearbox lift down
Remove from the engine the clutch plate and the pressure plate. Also, make positioning marks on the flywheel and on the engine case so that it can be mounted precisely in its original position afterward.
Figure 37: Oil seal
Before installing the new oil seal, make sure to clean up the crank. Then, apply a small amount of sealant like Permatex ultra gray on the outer surface of the oil seal. Install the new oil seal into the crankcase by using hands first and then gently knock the oil seal into its position. Make sure the seal lip is parallel to the surface of the crank.
Figure 38: Oil seal placement
Next, clean the flywheel with a little thinner so that the oil stain can be cleaned easily. Then add the thread lock to the flywheel nut so that the nut can securely adhere to the threaded crank and prevent loose nuts while the engine vibrates. Place the flywheel and fasten all the screws one by one with a torque of 98 ft-lbs.
Figure 39: Flywheel
Next, plug in the clutch plate with a clutch alignment tool so that the position of the clutch plate is exactly at the center of the flywheel. Attach the pressure plate and tighten the screws with torque around 14 to 15 ft-lbs. Lastly, clean up the gearbox from dirt and oil stain with chemicals before lifting up the gearbox and assemble it back with the engine.
Figure 40: Cleaning Gearbox