I. Preparation is Key:
* Gather Tools and Materials: You'll need a complete set of metric and standard sockets and wrenches, various screwdrivers, a transmission jack, engine hoist (possibly), a flywheel puller, a rear main seal installer/remover tool (highly recommended), a new rear main seal (ensure correct type for your engine), RTV sealant, clean rags, and plenty of shop towels. A torque wrench is absolutely essential.
* Safety First: Disconnect the negative battery terminal. Use jack stands to safely support the vehicle. Wear safety glasses and gloves.
* Fluid Drainage: Drain the engine oil and transmission fluid completely.
* Consult a Repair Manual: A factory service manual or a reputable aftermarket manual specific to your Pontiac 428 is crucial. It will provide detailed instructions, torque specifications, and diagrams unique to your engine.
II. Transmission Removal (Usually Necessary):
* Disconnect Components: Disconnect the driveshaft, shift linkage, electrical connections, and any other components connected to the transmission.
* Support the Transmission: Use a transmission jack to safely support the transmission while you remove the bolts attaching it to the engine.
* Remove the Transmission: Carefully lower the transmission using the jack.
III. Rear Main Seal Replacement:
* Flywheel Removal: Remove the flywheel. This typically requires a flywheel puller and may necessitate some persuading.
* Inspect the Crankshaft: Carefully inspect the crankshaft for any damage or scoring. Any damage should be addressed before installing the new seal.
* Remove the Old Seal: Use a rear main seal installer/remover tool to carefully remove the old seal. Avoid damaging the crankshaft during this process. A pick or screwdriver can work, but the tool is far less risky.
* Clean the Seal Surface: Thoroughly clean the crankshaft seal surface using a suitable cleaner. Remove any residual seal material, debris, or oil.
* Install the New Seal: Use the installer tool to carefully install the new rear main seal, ensuring it's seated correctly and evenly.
* Apply Sealant (If Necessary): Some seals might require a thin bead of RTV sealant on the outer lip of the seal before installation – check your manual.
IV. Reassembly:
* Reinstall the Flywheel: Carefully reinstall the flywheel, ensuring it's properly aligned and torqued to the specifications in your manual.
* Reinstall the Transmission: Carefully lift the transmission back into place using the transmission jack and bolt it securely to the engine. Reconnect all previously disconnected components.
* Refill Fluids: Refill the engine oil and transmission fluid to the proper levels.
* Start the Engine: Carefully start the engine and check for leaks. Let the engine run for a few minutes and then check for leaks again.
V. Important Considerations:
* Crankshaft End Play: Excessive crankshaft end play can damage the rear main seal. This should be checked and corrected if necessary.
* Pilot Bearing: Inspect and replace the pilot bearing if needed.
* Professional Help: If you are not comfortable performing this repair, take your vehicle to a qualified mechanic. This is a complex job that can easily lead to engine damage if not done properly.
This is a highly simplified overview. Always refer to a detailed repair manual specific to your Pontiac 428 engine for precise instructions, torque specifications, and safety precautions. The process can vary slightly depending on the year and specific model of your engine. Failure to follow proper procedures can result in costly repairs or even engine failure.
