1. Preparation:
* Safety First: Disconnect the negative battery cable to prevent electrical shorts.
* Gather Tools: You'll need a variety of tools, including wrenches (various sizes), sockets, screwdrivers (Phillips and flathead), possibly a radiator flush kit, and possibly a transmission jack (depending on the configuration).
* Drain Coolant: Completely drain the old coolant from the radiator, engine block, and heater core. Have a large container ready to catch the used coolant. Dispose of the coolant properly according to local regulations.
* Gather Supplies: New coolant, new radiator hoses (upper and lower), possibly new clamps, and potentially a new thermostat and gasket.
2. Removal of Old Radiator (If Applicable):
* Disconnect Hoses: Carefully disconnect the upper and lower radiator hoses from the radiator. They may be brittle and prone to breaking, so be gentle. Have rags ready to absorb any spilled coolant.
* Disconnect Transmission Cooler Lines (if applicable): If your radiator has transmission cooler lines attached, disconnect them carefully.
* Disconnect Fan: Remove the fan shroud and fan assembly (if applicable, sometimes the fan is attached directly to the radiator).
* Remove Radiator Support: You'll likely need to loosen or remove the radiator support brackets to give yourself enough room to maneuver the radiator out.
* Remove Radiator: Carefully lift the radiator out from the engine compartment. It can be heavy, so enlist help if needed.
3. Installation of New Radiator:
* Inspect the New Radiator: Ensure it's the correct one for your vehicle.
* Install Radiator Support (if removed): Reinstall the radiator support brackets if you removed them earlier.
* Position New Radiator: Carefully position the new radiator in the engine compartment, ensuring it's correctly aligned with the radiator support.
* Connect Transmission Cooler Lines (if applicable): Reconnect the transmission cooler lines if applicable.
* Connect Hoses: Carefully attach the upper and lower radiator hoses to the new radiator, using new clamps if necessary. Make sure the hoses are properly seated and clamped securely.
* Install Fan and Shroud (if removed): Reinstall the fan shroud and fan assembly.
* Refill System: Carefully refill the cooling system with the correct type and amount of coolant, following the instructions in your repair manual. Bleed the air from the system thoroughly to prevent overheating. This is crucial and often involves opening bleed valves or running the engine for a while with the heater on.
4. Testing and Final Steps:
* Check for Leaks: Carefully inspect all connections for leaks.
* Reconnect Battery: Reconnect the negative battery cable.
* Start Engine: Start the engine and let it run for a while to ensure the cooling system is working correctly. Monitor the temperature gauge closely. Look for any leaks.
Important Notes:
* Repair Manual: A factory service manual or a Haynes/Chilton manual specific to your 1971 Pontiac Lemans is essential. It will provide detailed instructions, diagrams, and torque specifications for your specific model.
* Professional Help: If you're uncomfortable performing this repair, it's best to take your vehicle to a qualified mechanic. A poorly installed radiator can lead to engine damage.
* Coolant Type: Use the correct type of coolant for your vehicle.
This is a general overview. Always consult your repair manual for specific instructions and safety precautions. The process can vary depending on the specific model and engine of your 1971 Pontiac Lemans. Remember safety first!
