GMC 12591866 Seal Assembly, Crankshaft Rear Oil

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The one-piece rear crankshaft seal is pressed into the engine block and the crankcase reinforcement section. Remove the transaxle, the clutch components, if equipped, and the flywheel. Pry out the old seal with a special seal removal tool or a flat-blade screwdriver. Caution: To prevent an oil leak after the new seal is installed, be very careful not to scratch or otherwise damage the crankshaft sealing surface or the bore in the engine block. Clean the crankshaft and seal bore in the block thoroughly and degrease these areas by wiping them with a rag soaked in lacquer thinner or acetone. Lubricate the lip of the new seal and the outer diameter of the crankshaft with engine oil. Position the new seal onto the crankshaft. Make sure the edges of the new oil seal are not rolled over. Note: When installing the new seal, if so marked, the words THIS SIDE OUT on the seal must face out, toward the rear of the engine. Use a special rear crankshaft seal installation tool or a socket with the exact diameter of the seal to drive the seal in place. Make sure the seal is not off-set; it must be flush along the entire circumference of the engine block and the crankcase reinforcement section. The remainder of installation is the reverse of removal.

The one-piece rear crankshaft seal is pressed into the engine block and the crankcase reinforcement section. Remove the transaxle, the clutch components, if equipped, and the flywheel. Pry out the old seal with a special seal removal tool or a flat blade screwdriver. To prevent an oil leak after the new seal is installed, be very careful not to scratch or otherwise damage the crankshaft sealing surface or the bore in the engine block. Clean the crankshaft and seal bore in the block thoroughly and degrease these areas by wiping them with a rag soaked in lacquer thinner or acetone. Lubricate the lip of the new seal and the outer diameter of the crankshaft with engine oil. Position the new seal onto the crankshaft. Make sure the edges of the new oil seal are not rolled over. When installing the new seal, if so marked, the words THIS SIDE OUT on the seal must face out, toward the rear of the engine. Use a special rear crankshaft seal installation tool or a socket with the exact diameter of the seal to drive the seal in place. Make sure the seal is not off-set; it must be flush along the entire circumference of the engine block and the crankcase reinforcement section. The remainder of installation is the reverse of removal.

Install a new center bolt and tighten it to the specified torque. Ensure you use a new pulley bolt. The remainder of the installation is the reverse of the removal procedure. Finally, reconnect the battery.

To prepare the vehicle, raise it and support it securely on jackstands. Additionally, remove the splash shield from below the engine compartment by removing the splash shield mounting bolts.

Check the surface on the pulley hub that the oil seal rides on. If the surface has been grooved from long-time contact with the seal, the pulley should be replaced with a new one.

The driveplate and oil pan need to be removed.

Use a seal puller to remove the crankshaft front oil seal.

Use a breaker bar and socket to remove the crankshaft pulley center bolt. A large pin spanner can be used to prevent the pulley from rotating while the bolt is loosened. Discard the old bolt and obtain a new one for installation. It's necessary to lock the pulley in position using a strap wrench or a large pin spanner. Wrap a length of the old drivebelt around the pulley for a good grip if using a strap wrench. Slide the puller off the nose of the crankshaft. If the pulley is stuck, use a puller that bolts to the three threaded holes in the pulley hub. Additionally, use a spacer to avoid damaging the crankshaft.

Raise the vehicle and support it securely on jackstands.