Mechanics

99 INTAKE GASKET

1999 Pontiac Firebird • 6 cylinder 2WD Automatic • 90 miles

I have to replace the plenum and intake manifold gaskets on a 99 pontiac Firebird 3.8 3800 series 2 rwd engine. First time to do this job, is there details? A step by step, or a video, or anything to help me not sweat this job as bad. It's my only car right now so when I take it down I have to be sure to have everything I need. I'm looking forward to the task, but I nervous about some aspects, like the injectors. (I have paid before and will gladly pay again, ya'll are the best)
Thanks guys

Avatar
Xxhoppxx
June 18, 2011.




It is going to be in two steps, the upper intake, and then the lower intake. The upper is more labor intensive, as electrical connections, vacuum lines, and the fuel rail need to be removed. I will forward you the literature step by step for both. There is alot of illustrations for the procedure that I would have to send individually. At this point I will include no illustrations, if you have a request for some, include a description of the ones you want ad I will attach them to this post as needed. One thing to mention, I know on the transverse 3.8, the upper intake can rot through by the EGR port and result in coolant entering the engine, I am not sure if the longitudinal plenum has the same possibility. If you are replacing because of this concern, you may already be aware of it.

Intake Manifold Replacement (Upper)
Removal Procedure
Tools Required
J 37088-A Fuel Line Quick Connect Separator

Disconnect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
Drain the engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.

Disconnect the intake air temperature (IAT) sensor electrical connector.

Remove the air intake duct.
Remove the drive belt tensioner. Refer to Drive Belt Tensioner Replacement.

Disconnect the fuel injector electrical connectors (1) from the fuel injectors.
Disconnect the manifold absolute pressure (MAP) sensor electrical connector (2).

Disconnect the engine harness vacuum tube (1) from the vacuum port.

Remove the fuel pressure regulator tube (2) from the following components: Manifold vacuum source (1)

Fuel pressure regulator valve (3)

Remove the manifold vacuum source screws (2).
Remove the manifold vacuum source (1) from the upper intake manifold.

Disconnect the fuel injector electrical connectors (1) from the fuel injectors.
Disconnect the EVAP canister purge valve switch electrical connector (2).
Relieve the fuel pressure. Refer to Fuel Pressure Relief in Engine Controls - 3.8L.

Disconnect the fuel lines (1) from the fuel rail using J 37088-A.
Disconnect the fuel vapor line (4) from the EVAP canister purge valve (5).

Remove the EVAP canister purge valve bolts (1).
Remove the EVAP canister purge valve (2) from the upper intake manifold.
Remove the ignition control module. Refer to Ignition Coil and Ignition Coil Module Replacement in Engine Electrical.

Reposition the brake booster hose clamp.
Remove the brake booster hose (2) from the upper intake manifold fitting (1).

Remove the captured secondary lock from the connector.
Disconnect the electronic throttle control (ETC) electrical connector (1).

Disconnect the following electrical connectors: Mass airflow (MAF) sensor (1)

Engine coolant temperature (ECT) sensor (2)

Remove the engine harness rosebud clip (3) from the throttle body.
Remove the engine harness clamp bolt (5) and harness clamp (4).
Reposition the engine wiring harness.
Remove the thermostat housing. Refer to Engine Coolant Thermostat Housing Replacement in Engine Cooling.
Disconnect the wiring harness rosebud clips from the fuel rail.
Reposition the wiring harness.

Remove the fuel rail nuts (1).
Important: Clean any dirt out of the injector bores with compressed air.

Remove the fuel rail (2) from the upper intake manifold.

Remove the throttle body bolt (1) and nuts (2).
Remove the throttle body (3) and gasket (4).

Remove the upper intake manifold bolts (1, 3, 4).
Remove the upper intake manifold (2).

Remove the upper intake manifold gasket (1).
Clean the upper and lower intake manifold sealing surfaces.

Remove the lower intake manifold O-rings seals (3, 4), if necessary.
Installation Procedure

Install new lower intake manifold O-ring seal (3, 4), if removed.

Install the upper intake manifold gasket (1).

Install the upper intake manifold (2) onto the lower intake manifold.
Install the upper intake manifold bolts (1, 3, 4).
Tighten

Tighten the upper intake manifold bolt (3) to 15 N m (11 lb ft).

Tighten the nine upper intake manifold bolts (4) to 10 N m (89 lb in).

Tighten the two upper intake manifold bolts (1) to 30 N m (22 lb ft).

Install the throttle body (3) and gasket (4).
Install the throttle body bolt (1) and nuts (2).
Tighten

Tighten the throttle body nuts (2) to 10 N m (89 lb in).

Tighten the throttle body bolt (1) to 10 N m (89 lb in).

Install the fuel rail (2) to the upper intake manifold.
Install the fuel rail nuts (1).
Tighten
Tighten the fuel rail nuts (1) to 8.5 N m (75 lb in).

Position the wiring harness.
Connect the wiring harness rosebud clips from the fuel rail.
Install the thermostat housing. Refer to Engine Coolant Thermostat Housing Replacement in Engine Cooling.
Position the engine wiring harness.

Install the engine harness clamp (4) and harness clamp bolt (5).
Tighten
Tighten the harness clamp bolt (5) to 6 N m (53 lb in).

Install the engine harness rosebud clip (3) to the throttle body.
Connect the following electrical connectors: Mass airflow (MAF) sensor (1)

Engine coolant temperature (ECT) sensor (2)

Connect the electronic throttle control (ETC) electrical connector (1).
Install the captured secondary lock from the connector.

Install the brake booster hose (2) to the upper intake manifold fitting (1).
Position the brake booster hose clamp.
Install the ignition control module. Refer to Ignition Coil and Ignition Coil Module Replacement in Engine Electrical.

Install the EVAP canister purge valve (2) to the upper intake manifold.
Install the EVAP canister purge valve bolts (1).
Tighten
Tighten the EVAP canister purge valve bolts (1) to 10 N m (89 lb in).

Connect the fuel vapor line (4) to the EVAP canister purge valve (5).
Connect the fuel lines (1) to the fuel rail.

Connect the EVAP canister purge valve switch electrical connector (2).
Connect the fuel injector electrical connectors (1) to the fuel injectors.

Install the manifold vacuum source (1) to the upper intake manifold.
Install the manifold vacuum source screws (2).
Tighten
Tighten the manifold vacuum source screws (2) to 10 N m (89 lb in).

Install the fuel pressure regulator tube (2) to the following components: Manifold vacuum source (1)

Fuel pressure regulator valve (3)

Connect the engine harness vacuum tube (1) to the vacuum port.

Connect the manifold absolute pressure (MAP) sensor electrical connector (2).
Connect the fuel injector electrical connectors (1) to the fuel injectors.
Remove the drive belt tensioner. Refer to Drive Belt Tensioner Replacement.

Install the air intake duct.

Connect the intake air temperature (IAT) sensor electrical connector.

Connect the negative battery cable. Refer to Battery Negative Cable Disconnection and Connection in Engine Electrical.
Refill the engine coolant. Refer to Cooling System Draining and Filling in Engine Cooling.

Intake Manifold Replacement (Lower)
Removal Procedure

Remove the upper intake manifold. Refer to Intake Manifold Replacement.
Remove the coolant temperature sensor.

Remove the O-ring seals (3, 4), if necessary.
Remove the lower intake manifold bolts (1).
Remove the lower intake manifold (2).

Remove the lower intake manifold seals (1).
Remove the lower intake manifold gaskets (2).
Installation Procedure

Install the lower intake manifold gaskets (2).
Install the lower intake manifold seals (1).
Apply silicone sealer GM P/N 12345366 or equivalent to the ends for the manifold seals (2).

Install the lower intake manifold (2).
Apply thread lock compound GM P/N 12345493 or equivalent to the bolt threads before installing.
Install the lower intake manifold bolts (1).
Tighten
Tighten the lower manifold bolts (1) to 15 N m (11 lb ft).

Remove the coolant temperature sensor.
Tighten
Tighten the coolant temperature sensor to 25 N m (18 lb ft).

Remove the upper intake manifold. Refer to Intake Manifold Replacement.

Factoryjack
Jun 18, 2011.


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