GM 12587621
Rear Main Seal

Mount replacement of the Crankshaft rear oil seal requires the disassembly of the Flywheel. The installer positions Crankshaft rear seal puller (J 43320) over guide pins from Crankshaft rear seal puller (J 43320) which have been inserted into the Crankshaft. Using a proper drill install eight self-drilling sheet metal screws across the rear Crankshaft Seal in a cross-pattern. The Crankshaft rear seal puller (J 43320) includes eight self-tapping screws for its installation. The Crankshaft puller assembly requires threads through its central bolt that slips into the Crankshaft to extract the seal. The guide pins should be extracted from the Crankshaft once the seal is removed. Confirm the Crankshaft has no surface abrasions or loose rust or burrs before moving ahead with assembly. Make all necessary corrections beforehand. Dampen the Crankshaft sealing surface with a slender drop of oil while excluding oil from the engine block's sealing surface. Place the Crankshaft rear seal installer (J 42849) on its seal before setting it against the Crankshaft and tightening screws into the facing tapped holes. Using a screwdriver, clamp down the screws on the Crankshaft rear seal installer (J 42849) firmly to achieve square alignment over the Crankshaft before rotating the center nut until complete bottoming occurs. Remove the Crankshaft rear seal installer (J 42849) then reinstall the Flywheel.

Remove the Front Cover Oil Seal Installer (J 42851) and reinstall the crankshaft balancer.

Loosen the oil pan.

Lubricate the outside diameter (OD) of the oil seal and the rear housing oil seal bore with clean engine oil.

Remove the J 41479 and reinstall the engine flywheel.

Do not lubricate the oil seal sealing surface and avoid reusing the crankshaft oil seal.

Apply a very light film of oil onto the crankshaft sealing surface, avoiding oil on the engine block's sealing surface.

Reinstall the crankshaft balancer.

Thread the J 41479 threaded rod into the tapered cone until it contacts the oil seal, align the oil seal into the tool, and rotate the handle of the tool clockwise until the seal is fully seated in the rear cover bore.

Use the Cover Aligner Seal Installer (J 35468) to install the new seal.

Securely tighten the screws with a screwdriver to ensure the seal is installed squarely over the crankshaft.

Remove the crankshaft balancer, taking care not to damage the engine front cover or the crankshaft sealing area.

Install the crankshaft front oil seal onto the J 41478 guide, insert the threaded rod into the end of the crankshaft, and use the J 41478 to install the oil seal into the cover bore.

That the crankshaft front seal is flush and square to the engine front cover.

Reinstall the flywheel.

Inspect the seal for proper orientation.