Here's a general overview. Specific steps will vary depending on the engine (3.4L, LT1, etc.):
1. Preparation:
* Safety First: Disconnect the negative battery terminal. This prevents accidental shorts and protects your electrical system.
* Gather Supplies: You'll need the new intake manifold gaskets (make sure you get the correct ones for your specific engine!), new bolts (highly recommended, as the old ones can be stretched), gasket sealant (high-temperature RTV silicone), a torque wrench, socket set, various wrenches, and possibly a breaker bar for stubborn bolts. Clean rags and a shop vacuum are also essential. Consult a repair manual specific to your engine for the correct torque specifications.
* Consult a Repair Manual: A factory service manual or a reputable aftermarket repair manual (like Haynes or Chilton) is crucial. These provide detailed instructions, diagrams, and torque specifications specific to your year and engine. This is not something to attempt without one.
2. Removal:
* Disconnect Components: Disconnect all components attached to the intake manifold: fuel injectors, vacuum lines, throttle body, various sensors (air temperature sensor, etc.), and the PCV valve. Take pictures as you go to help with reassembly. Label everything clearly if you're not confident remembering.
* Remove the Upper Intake Manifold: This usually involves removing bolts securing it to the lower intake manifold. Be careful not to drop anything into the engine.
* Remove the Lower Intake Manifold: This is more involved and will require removing more components and bolts depending on the engine. You might need to disconnect coolant hoses, and carefully support the manifold as you remove it.
3. Cleaning and Inspection:
* Clean mating surfaces: Thoroughly clean the mating surfaces of both the intake manifold and the engine block using a parts cleaner and rags. Remove any old gasket material, dirt, or debris.
* Inspect for damage: Check for any cracks or damage to the intake manifold itself. Replace the manifold if necessary.
4. Installation:
* Apply Sealant: Apply a thin, even bead of high-temperature RTV silicone sealant to the mating surfaces as directed by the sealant manufacturer and your repair manual. Don't overdo it.
* Install Gaskets: Carefully install the new intake manifold gaskets.
* Install the Lower Intake Manifold: Carefully align the lower intake manifold and install the bolts, tightening them in stages as specified in your repair manual, using a torque wrench. Tighten in a criss-cross pattern to ensure even pressure.
* Install the Upper Intake Manifold: Install the upper intake manifold, again tightening bolts in stages and in the correct pattern to the specified torque.
* Reconnect Components: Reconnect all components that were disconnected earlier, ensuring everything is properly seated and secured.
5. Final Steps:
* Reconnect Battery: Reconnect the negative battery terminal.
* Check for Leaks: Start the engine and check for any leaks around the intake manifold. Look for coolant leaks, vacuum leaks, and fuel leaks. Let the engine run for a while to make sure everything is stable.
Important Considerations:
* Torque Specifications: Using a torque wrench and adhering to the manufacturer's specifications is absolutely critical. Over-tightening can crack the manifold or engine block. Under-tightening can lead to leaks.
* Coolant: Be prepared for some coolant loss during this process. Have coolant on hand to refill the system.
* Engine Type: The exact procedure will vary significantly depending on whether you have the 3.4L V6 or the 5.7L LT1 V8 engine. The repair manual is your best friend here.
Again, this is a complex job. If you're unsure about any step, consult a professional mechanic. Improperly completed repairs can result in significant engine damage.
