GMC 10128316 Timing Cover Oil Seal

Remove the cable from the negative battery terminal. Remove the drive belt. Raise the vehicle and securely place it on jackstands. Remove the hub retaining bolt. Place a bar through one of the pulley holes and wedge it against the bottom of the front cover to keep the pulley from turning while loosening the pulley bolts. Remove the pulley hub. Use a puller if necessary. Note how the seal is installed-the new one must face the same direction! Carefully pry the Crankshaft Seal out of the cover with a seal puller or a large screwdriver. Be very careful not to distort the cover or scratch the crankshaft! Apply a thin layer of engine oil or multi-purpose grease to the Crankshaft Seal lip and to the outer edge of the new seal. Install the seal in the cover with the lip (open end) facing IN. Drive the seal into place with a large socket and a hammer. Make sure the seal enters the bore squarely and is driven in until the front face is flush with the cover. The seal can also be replaced if the timing chain cover has been removed for other work. Support the cover on a block of wood and drive the seal out from the backside. Install a new seal into the bore. Reinstall the timing chain cover with a bead of RTV sealant applied to the mating surface of the oil pan. Apply a small amount of RTV sealant on the crankshaft Woodruff key. Align the slot in the hub with the crankshaft Woodriff key, then press the hub onto the crankshaft until it bottoms against the crankshaft timing gear. The hub retaining bolt can be used to press the hub into position. Install the crankshaft pulley on the hub. Use a non-hardening thread-locking compound on the bolt threads. Tighten the hub-to-crankshaft bolt. Install the drive belt.