The 3.1L engine is equipped with upper and lower intake manifolds. The upper intake manifold is also known as the intake manifold plenum.
The fuel system is under pressure and must be properly relieved before disconnecting the fuel lines. Failure to properly relieve the fuel system pressure can lead to personal injury and component damage.
Relieve the fuel system pressure.
Disconnect the negative battery cable.
Remove the top half of the air cleaner assembly and throttle body duct.
Drain and recycle the engine coolant.
Disconnect the EGR pipe from exhaust manifold.
Remove the serpentine belt.
Remove the brake vacuum pipe at the intake plenum.
Disconnect the control cables from the throttle body and intake plenum mounting bracket.
Remove the power steering lines at the alternator bracket.
Remove the alternator.
Label and disconnect the ignition wires from the spark plugs and wire retainers on the intake plenum.
Remove the ignition assembly and the EVAP canister purge solenoid together.
Exploded view of the upper and lower intake manifold and fasteners
Detach the upper engine wiring harness connectors from the following components:
Throttle Position (TP) sensor
Idle Air Control (IAC) valve
Engine Coolant Temperature (ECT) sensor
Manifold Absolute Pressure (MAP) sensor
Camshaft Position (CMP) sensor
Tag and disconnect the vacuum lines from the following components:
Fuel pressure regulator
Disconnect the MAP sensor from the upper intake manifold.
Remove the upper intake plenum mounting bolts and lift off the plenum.
Disconnect the fuel lines from the fuel rail and bracket.
Install a suitable engine support fixture tool.
Remove the right side engine mount.
Remove the power steering mounting bolts and support the pump out of the way without disconnecting the power steering lines.
Disconnect the coolant inlet pipe from the outlet housing.
Remove the coolant bypass hose from the water pump and the cylinder head.
Disconnect the upper radiator hose from the thermostat housing.
Remove the thermostat housing.
Remove both rocker arm covers.
Remove the lower intake manifold bolts. Make sure the washers on the four center bolts are installed in their original locations.
When removing the valve train components they should be kept in order for installation the original locations.
Remove the rocker arm retaining nuts or bolts and extract the rocker arms and pushrods.
Remove the intake manifold from the engine. Remove and discard the gasket.
Using a suitable scraper, clean gasket material from all mating surfaces. Remove all excess RTV sealant from front and rear ridges of cylinder block.
Place a 0.12 inch (3mm) bead of RTV, on each ridge, where the front and rear of the intake manifold contact the block.
Using a new gasket, place the intake manifold on the engine.
Install the pushrods in their original locations. Coat the pushrods with prelube.
The intake pushrods are marked yellow (5 3/4 inch long) and the exhaust are green (6 inches long). Make sure the pushrods are properly seated in the valve lifters and rocker arms.
Position the rocker arms in their original locations and tighten to the proper specifications.
Install lower the intake manifold attaching bolts. Apply sealant or equivalent thread locking compound to the threads of bolts. Tighten the vertical bolts first, then the diagonal bolts to 115 inch lbs. (13 Nm).
Install the front rocker arm cover.
Install the thermostat housing.
Connect the upper radiator hose to the thermostat housing.
Fasten the coolant inlet pipe to the thermostat housing.
Connect the coolant bypass pipe at the water pump and cylinder head.
Install the power steering pump in the mounting bracket.
Loosely install the serpentine belt.
Connect the right side engine mount.
Remove the special engine support tool.
Fasten the fuel lines to fuel rail and bracket.
Install the upper intake manifold and tighten the mounting bolts to 18 ft. lbs. (25 Nm).
Install the MAP sensor.
Connect the upper engine wiring harness connectors to the related components removed earlier.
Connect the vacuum lines to the PCV, vacuum modulator and fuel pressure regulator.
Install the EVAP canister purge solenoid and ignition assembly.
Install the alternator assembly.
Connect the power steering line to the alternator bracket.
Install the serpentine belt.
Connect the spark plug wires to the spark plugs and intake plenum wire retainer.
Install the EGR pipe to the exhaust manifold.
Attach the control cables to the throttle body lever and upper intake plenum mounting bracket.
Install air intake assembly and top half of the air cleaner assembly.
Install the brake vacuum pipe.
Fill the cooling system.
Connect the negative battery cable, then start the vehicle and verify that there are no leaks.