GM 10172811 Manifold, Intake

For removing the intake manifold, start by disconnecting the negative battery cable and draining the cooling system. Then take off air cleaner assembly, throttle body (if intending to resurface or replace the manifold), alternator rear brace, and on air-conditioned models move the compressor out of the way by removing brackets. Next is to unfasten ESC module bracket located on side of manifold, remove idler pulley rear bracket, and label as well as disconnect all fuel lines, wires and vacuum hoses connected to intake manifold looking for interference with other components like transmission dipstick tube, EGA system, PCV system and power brake lines. Detach upper radiator hose from thermostat housing cover and if present disconnect heater fitting in intake manifold. Distributor and ignition coil wires should be removed. Unbolt mounting bolts incrementally until they can be removed by hand with care not to harm gasket sealing surfaces. Pry bar can be placed underneath cast-in lug near thermostat housing to assist in prying up front of manifold when it sticks. Ensure cylinder heads, block and manifold mating surfaces are immaculately clean before installing; this entails removing any sealant or old gasket material using a gasket scraper and wiping surfaces with lacquer thinner or acetone. Remove shop rags covering lifter valley so that no dirt enters engine; then take a tap followed by compressed air to clean bolt holes. Apply thin coat of ATV sealant around coolant passage holes located on cylinder head side of new intake manifold gaskets; position them on cylinder heads being mindful of correct alignment as well as orientation. Front and rear end seals must be installed on 7.4L V8 engines while a 3/16-inch bead of ATV sealant is applied to each corner of end seals where they meet gaskets. Tap threads in bolt holes with correct size tap and apply Loctite 242 or equivalent threadlocker to threads on manifold bolts before installing and torquing bolts to the specified torque sequence. Finally, perform the reinstallation steps in reverse order, start the engine, and carefully inspect for oil, vacuum, and coolant leaks at the intake manifold joints. Disconnect negative battery cable; drain cooling system on 1996 and later models with upper intake manifold removal. Remove air cleaner assembly, ducts, any interfering wiring, throttle and cruise control cables and brackets as well as fuel lines (V6 and small-block VB engines). Coil and bracket also should be removed while PCV hose from EGR inlet tube purge solenoid connectors is removed together with any interfering spark plug wires from 7.4L V8 models. To install upper intake manifold, position gasket and manifold; then tighten bolts in two steps using a criss-cross pattern followed by other installation steps in reverse order.

Fuel injector replacement (CSFI) includes removing and reinstalling the fuel meter body.

Drain the cooling system and detach the fuel lines, vacuum lines, and wire leads from the fuel injection assembly, being prepared to catch any fuel and plugging the line to prevent contamination.

For TBI engines, unbolt the ESC module/bracket and position it out of the way, then detach the engine oil filler tube and transmission dipstick from the alternator bracket, removing the alternator bracket from the intake manifold.

To begin removing the intake manifold, first disconnect the negative battery cable and drain the cooling system.

Disconnect the negative battery cable, remove the upper fan shroud, air cleaner assembly, drain the cooling system, and disconnect the upper radiator and heater hoses.

Follow similar steps starting from removing the upper fan shroud, air cleaner assembly, draining the cooling system, and disconnecting the upper radiator and heater hoses. Unbolt the EGR valve, move heater hoses, and remove the ignition coil. Remove the small brace from the air conditioning compressor to the intake manifold and turn the engine to TDC for number 1 piston before removing the distributor.

The first step is to disconnect the cable from the negative battery terminal to ensure electrical safety.

To secure the new manifold to the cylinder head, place a new gasket on the manifold, hold the manifold in position against the cylinder head, and install the mounting nuts finger-tight.