Hummer 12580678 Manifold, Intake

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The water pump intake hose and drivebelt should also be removed.

The air filter housing outlet duct and the alternator need to be removed.

The air filter housing outlet duct and the alternator need to be removed.

Start by removing and installing intake manifolds. Disconnect the negative battery cable. The lower intake manifold has to be removed to be able to access it. Remove the alternator and air filter housing outlet duct. Take note of all wires connected to the intake manifold that must be disconnected when removed including harness retainer and clips. Disengage the power brake vacuum hose, canister purge solenoid hose, fuel line from the fuel rail and PCV hose from the intake manifold. There are any remaining electrical connectors or vacuum hoses attached to either throttle body or intake manifold located then disconnect them as well. Loosen the mounting bolts for the intake manifold in reverse order until they can be removed by hand. In such a case, you may have to use a pry bar to gently break the gasket seal. Lift and remove the intake manifold taking care not to miss anything that may still be attached. When installing, carefully clean off gasket surfaces without aggressively scraping which could damage sealing surfaces then wipe them down with safety solvent. Clear out debris from bolt holes using tap and compressed air, snap new gaskets onto manifold ensuring they are firmly seated, cautiously place it down, then proceed with tightening of bolts according to specified torque values in sequence given that is indicated in manufacturer's instruction manual. Avoid over tightening. Finally reverse steps taken earlier, start car engine up and check if there is any leakage at any of the joints in this area on a vacuum basis after all this is done.

To remove the intake manifold, you need to loosen the intake lower manifold mounting bolts and pry up the manifold to break the gasket seal.

The new gaskets should be positioned on the manifold, ensuring they snap into place.

To remove the intake manifold, you need to loosen the intake lower manifold mounting bolts and pry up the manifold to break the gasket seal.

To start with, disconnect the cable from the battery's negative terminal prior to eliminating the intake manifold. Also, drain coolant and remove ignition coil as well as EVAP canister tube. In addition, sever heater hoses; throttle body wiring, and numerous electrical connectors. Moreover, get rid of PCV valve hose; power brake booster hose, and radiator hose. Furthermore, drop water pump intake hose together with drivebelt. And then, release power steering pump bracket nut and bolts. Finally, shift power steering pump bracket forward in order to reach the bolt at front of intake manifold. Therefore, remove intake lower manifold mounting bolts and pry up manifold to break gasket seal. Eventually loosen all connections attaching the intake manifold while ensuring nothing is still attached. For installation purposes: clean mating surfaces and tap thread in bolt holes; apply RTV sealant on front and rear manifolds' mating surfaces plus a thin ring around new intake manifold gaskets' cylinder head side coolant passage holes; place gaskets accordingly while sealant is still wet then set the manifold in position; install bolts eventually following recommended sequence; finally perform remaining tasks in reversed manner fill cooling system again and check for leaks at joints between intake manifolds.

Other components that need to be disconnected include the heater hoses, throttle body wiring, and various electrical connectors.

Before installing the new intake manifold, you should clean the mating surfaces and tap the threads in the bolt holes.