Upper intake manifold exploded while starting

BHASKAR KOLHE

MEMBER
2000 BUICK LESABRE
3.8L
6 CYL
AUTOMATIC
85,000 MILES

After 4 days in the carport, I turned the ignition switch to start the engine and there was a big bang and smoke and burning smell coming from the engine. When I opened the hood, the force of explosion had thrown the plastic cover ripping the oil filler and the upper manifold. I am sorry I could not attach picture since there is no paste option.

1 Reply

ASEMASTER6371

MECHANIC
52,797 POSTS

Good afternoon,

The car backfired in the plenum and that is what caused the explosion. That was a common issue in the older days with the plastic intake manifold.

https://www.2carpros.com/articles/engine-backfires-while-running

The manifold will have to be replaced along with any other damaged parts and then the reason for the backfire needs to be traced down.

Roy

1. Disconnect the negative battery cable.
2. Remove the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement.
3. Remove the air cleaner intake duct. Refer to Air Cleaner Intake Duct Replacement in Powertrain Management.
4. Disconnect the spark plug wires from the right side of the engine. Set the wires aside.
5. Remove the manifold vacuum source.
6. Depressurize the fuel lines. Refer to Fuel Pressure Relief Procedure in Powertrain Management.
7. Remove the fuel rail. Refer to Fuel Rail Assembly Replacement in Powertrain Management.
8. Remove the EGR heat shield.
9. Remove the cable bracket to the cylinder head mounting bolt.
10. Remove the accelerator cable. Refer to Accelerator Controls Cable Replacement in Powertrain Management.
11. Remove the throttle body support bracket.

Notice: Refer to Lower Intake Manifold To Cylinder Head Bolt Notice.

12. Remove the upper intake manifold bolts.
13. Remove the upper intake manifold.
14. Remove the upper intake manifold gasket.

Installation Procedure

Notice: Refer to Lower Intake Manifold To Cylinder Head Bolt Notice in Service Precautions.

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1. Install the upper intake manifold gasket.
2. Remove the upper intake manifold.

Notice: Refer to Fastener Notice in Service Precautions.

3. Install the upper intake manifold bolts.
- Tighten the bolts in sequence to 10 Nm (89 inch lbs.).
4. Install the throttle body support bracket.
5. Install the accelerator cable. Refer to Accelerator Controls Cable Replacement in Powertrain Management.
6. Install the cable bracket to the cylinder head mounting bolt.
7. Install the EGR heat shield.
8. Install the fuel rail. Refer Fuel Rail Assembly Replacement in Powertrain Management.
9. Install the manifold vacuum source.
10. Connect the spark plug wire(s) to the right side of the engine.
11. Install the air cleaner intake duct. Refer to Air Cleaner Intake Duct Replacement in Powertrain Management.
12. Install the fuel injector sight shield. Refer to Fuel Injector Sight Shield Replacement.
13. Connect the negative battery cable.

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