Here's a general outline. This is not a comprehensive guide and should be supplemented with a repair manual specific to your vehicle. A Haynes or Chilton manual is highly recommended. Improper procedures can lead to injury or further damage to your vehicle.
Tools you'll likely need:
* Jack and Jack Stands: Absolutely essential for safety.
* Wheel Chocks: To secure the vehicle.
* Engine Support Bar: Crucial to prevent the engine from falling. Renting one is a good idea if you don't own one.
* Torque Wrench: To tighten bolts to the proper specifications (found in your repair manual).
* Sockets and Wrenches (metric): A variety of sizes will be needed.
* Ratchet and Extensions: To reach those hard-to-access bolts.
* Pry Bar: Might be helpful to break loose stubborn bolts.
* Penetrating Oil (like PB Blaster): Soak bolts before attempting to remove them.
* New Engine Mounts: Get the correct ones for your model year and engine.
* Gloves and Safety Glasses: Protect yourself.
Steps (General):
1. Preparation: Disconnect the battery negative terminal. Consult your repair manual for any other necessary disconnections (e.g., electrical connections near the mounts).
2. Vehicle Support: Securely jack up the vehicle and place it on jack stands. Always use wheel chocks on the wheels that remain on the ground.
3. Engine Support: Install the engine support bar. This is CRITICAL to prevent the engine from falling and causing damage or injury. Connect the bar securely to the engine and a solid point on the vehicle's frame.
4. Access the Mounts: Locate the engine mounts. There are typically two, one on each side of the engine. You'll likely need to remove some components to access the mounting bolts fully (this is where your repair manual will be invaluable). This might involve removing some heat shields, exhaust components, or other parts.
5. Remove the Old Mounts: Use the appropriate sockets and wrenches to remove the bolts securing the old engine mounts to the engine and the chassis. Penetrating oil will likely be your friend here. Be patient and avoid stripping the bolts.
6. Install the New Mounts: Carefully install the new engine mounts, ensuring they are properly seated. Use the repair manual as a guide; there might be specific alignment requirements.
7. Tighten Bolts: Tighten the bolts to the torque specifications listed in your repair manual. This is crucial to prevent problems.
8. Remove Engine Support: Carefully remove the engine support bar after all bolts are tightened.
9. Lower the Vehicle: Slowly lower the vehicle using the jack.
10. Reconnect Battery and Test: Reconnect the negative battery terminal and start the engine. Check for any unusual noises or vibrations. Test drive the vehicle carefully to ensure the mounts are properly installed and functioning correctly.
Important Considerations:
* Repair Manual: Get a repair manual for your specific 1991 Cadillac Coupe DeVille with the 4.9L engine. This is not a substitute for the detailed instructions and diagrams found in a professional manual.
* Bolt Sizes and Torque Specs: The repair manual will provide the correct sizes and torque specs for all bolts. Using incorrect torque can damage the engine mounts or surrounding components.
* Difficulty: This is not a beginner job. If you're not comfortable working on cars, consider taking it to a qualified mechanic.
Remember safety first! If you're unsure about any step, seek professional help. Improperly installed engine mounts can lead to significant damage to your vehicle.
