GM 10087650 Plenum,Intake Manifold

If the vehicle has air-conditioning, examine the routing of the hoses and the compressor mounting carefully, as it may be possible to remove the intake manifold without disconnecting the system; if uncertain, consult a dealer or refrigeration specialist for system depressurization. Begin by disconnecting the cable from the negative battery terminal and draining the coolant from the radiator. For carbureted models, remove the air cleaner assembly, tagging each disconnected hose with numbered tape for easier reinstallation, then label and disconnect all electrical wires and vacuum hoses at the carburetor, followed by disconnecting the fuel line and plugging it to prevent contamination. Disconnect the throttle cable, spark plug wires, and wires at the coil, using numbered tape for labeling. Remove the distributor cap, distributor, power brake fitting, and mounting bracket, then move the power brake tube aside. Remove the solenoid/hose bracket, left and right rocker arm covers, upper radiator hose, heater hose, and vacuum lines from the TVS switch, along with the electrical connector from the coolant switch. Ensure all interfering wires, vacuum hoses, and coolant hoses are disconnected. If replacing the manifold, transfer external components from the old manifold, including the carburetor choke assembly, coolant switch, EGR valve, and emissions system TVS valve. Remove the manifold mounting bolts and separate the manifold from the engine without prying between mating surfaces; tap it gently with a hammer and wooden block if necessary. If installing a new manifold, transfer external components and clean the engine cavity, block, cylinder head, and gasket surfaces thoroughly, removing all gasket material and dirt. Apply a bead of R1V sealant to the engine block gasket surfaces, install new intake gaskets marked for the correct cylinder heads, and hold them in place with extended sealant. Carefully lower the intake manifold into position, ensuring the gaskets remain undisturbed, then install and tighten the mounting bolts according to the recommended sequence. Reinstall remaining components in reverse order, fill the radiator with coolant, start the engine, and check for leaks while adjusting ignition timing and idle speed as necessary. For fuel-injected models, remove the port fuel-injection components, disconnect spark plug wires and coil wires, and remove the distributor cap and distributor. Remove the air management hose, emission canister hoses, and rocker arm covers, then disconnect the upper radiator hose and heater hose, and remove coolant switches from the manifold. Loosen and remove the intake manifold bolts, separate the manifold from the engine without prying, and clean the mating surfaces thoroughly. If installing a new manifold, transfer external components and follow the remaining procedure as previously outlined.

Disconnect all other hoses connected to the carburetor, identifying each hose with strips of numbered tape to prevent confusion upon reassembly.

Ensure all interfering electrical wires, vacuum hoses, and coolant hoses are disconnected before separating the manifold from the engine without prying between mating surfaces.

Disconnect the accelerator linkage at the carburetor, ensuring any supporting bracket is also removed.

Disconnect the temperature sending unit wire, vacuum hoses from the distributor, TVS, and EFE valve pipe at the carburetor (mark hoses with tape for ease of reassembly), and the coolant by-pass hose at the manifold.

Label and disconnect the fuel line, vacuum lines, and electrical leads from the throttle body assembly, being prepared to catch some fuel when disconnecting the fuel line and plugging it to prevent contamination.