GM 12575084 Manifold Assembly, Lower Intake

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Disconnect the cable from the negative battery terminal. Remove the air filter housing and the intake air duct. Disconnect the throttle body solenoid, the intake manifold runner control solenoid, and any other electrical connector that will interfere with the intake manifold removal. Remove the vacuum hoses from the intake manifold runner control vacuum actuator and the vacuum solenoid. Remove the clamps from the intake manifold runners at the upper intake manifold. Disconnect the EGR pipe from the upper intake manifold. Remove the upper intake manifold mounting bolts and lift the manifold from the engine. Clamp off, then disconnect the coolant hose from the throttle body after the upper intake manifold has been slightly lifted. Carefully set the upper intake manifold in place. Install the upper intake manifold bolts. Tighten the bolts to the specific torque. Install the intake manifold runners at the intake manifold. Tighten the clamp bolts to the specific torque. The remaining installation steps are the reverse of removal. Check the coolant level, adding as necessary. Reconnect the battery, then start the engine and check carefully for leaks. To remove the lower intake manifold, follow these steps: Remove the upper intake manifold and the intake manifold runners. Depressurize the fuel system, then remove the fuel rail and injectors. Remove the lower intake manifold mounting bolts. Remove the lower intake manifold spacer from the engine block. Remove the O-rings from the lower intake manifold spacer. Clean the surface of the spacer and the engine block. Clean the mating surfaces with lacquer thinner or acetone. When working on the cylinder heads and engine block, cover the open engine areas with shop rags to keep debris out of the engine. Use a vacuum cleaner to remove any material that falls into the intake ports in the cylinder heads. Use a tap of the correct size to chase the threads in the bolt holes, then use compressed air (if available) to remove the debris from the holes. Install the new O-rings into the spacer. Install the spacer onto the engine block. Carefully set the lower intake manifold in place. Don't disturb the spacer and don't move the lower intake manifold fore-and-aft after it contacts the spacer on the engine block. Install the lower intake manifold bolts and tighten them to the specific torque. Apply a small amount of thread locking compound to the lower intake manifold bolt threads. The remaining installation steps are the reverse of removal. Check the coolant level, adding as necessary. Reconnect the battery, then start the engine and check carefully for leaks.

Disconnect the cable from the negative battery terminal. Remove the throttle body. Disconnect any electrical connectors that would interfere with manifold removal. Open the wiring harness clips and detach all wiring harnesses from the manifold. Disconnect any vacuum hoses connected to the manifold, marking the hoses, if necessary, to ensure correct reassembly. Remove the dipstick tube mounting bolt and position the dipstick to the side. Remove the intake manifold mounting bolts and nuts. Lift the intake manifold from the engine compartment. Install a new gasket, if necessary. Note: The intake manifold gasket does not need to be replaced unless it has become damaged during the removal process. Make sure the mating surfaces of the manifold and cylinder head are clean. Install the manifold over the studs on the cylinder head. Install the bolls and nuts and tighten them finger-tight. Tighten the bolls to the specific torque, starting with the center bolls and working towards the ends. The remainder of installation is the reverse of the removal steps. Reconnect the battery. Run the engine and check for vacuum leaks.