Intake manifold and Valve Lifter Oil Manifold (VLOM) — removal and installation

Warning: Wait until the engine is completely cool before starting this procedure.

Removal

Intake manifold

1. Disconnect the cable from the negative terminal of the battery (see Engine electrical systems).
Relieve the fuel system pressure (see Fuel and exhaust systems).

2. Refer to Fuel and exhaust systems and remove the air filter housing outlet duct.

3. Label, then disconnect all of the engine wiring harnesses that interfere with intake manifold removal. Also detach all the harness retainers and clips. Move the detached harnesses aside and secure them out of the way.

Note: Clear labeling will make the assembly procedure go smoothly and quickly.

4. Disconnect the hose from the canister purge solenoid (see Emissions and engine control systems). Disconnect the fuel line from the fuel rail (see Fuel and exhaust systems). Disconnect the PCV hose from the intake manifold.

5. Disconnect any remaining electrical connectors or vacuum hoses connected to the intake manifold or throttle body.

6. Loosen the intake manifold mounting bolts in 1/4-turn increments until they can be

removed by hand (see illustrations).

7.6a Loosen the bolts in 1/4-turn increments on the left side …

Chevrolet Silverado V6 engine 4,3L _ Loosen the bolts in 1/4-turn increments on the left side

7.6b … then on the right side until all the bolts can be removed by hand

Chevrolet Silverado V6 engine 4,3L _ Intake manifold and Valve Lifter Oil Manifold (VLOM) - removal and installation

Caution: Do not pry between the manifold and the heads or damage to the gasket sealing surfaces may result and vacuum leaks could develop. Also, don’t use too much force — the manifold is made of a plastic composite and could crack.

7. Remove the intake manifold. As the manifold is lifted from the engine, be sure to check for and disconnect anything still attached.

Valve Lifter Oil Manifold (VLOM)

8. Remove the fuel pump insulator (see illustration).

7.8 Remove the insulator from the top of the valve lifter oil manifold

Chevrolet Silverado V6 engine 4,3L _ Remove the insulator from the top of the valve lifter oil manifold

9. Remove the fuel rail and injectors (see Fuel and exhaust systems).

10. Remove the balance shaft sprocket (see Balance shaft, chain and sprockets — removal and installation).

11. Remove the Valve Lifter Oil Manifold (VLOM) assembly mounting bolts (see illustrations).

7.11a Valve Lifter Oil Manifold (VLOM) assembly details

1 Oil pressure sensor
2 Valve Lifter Oil Manifold
3 Valve lifter oil filter plug
4 Mounting bolts
5 High-pressure fuel lines and fuel rails

Chevrolet Silverado V6 engine 4,3L _ Valve Lifter Oil Manifold (VLOM) assembly details

7.11b The Valve Lifter Oil Manifold (VLOM) gasket (A) can be re- used if it’s in good condition. Don’t pick up the assembly by the electrical lead frame (B)

Chevrolet Silverado V6 engine 4,3L _ The Valve Lifter Oil Manifold (VLOM) gasket (A) can be re- used if it's in good condition. Don't pick up the assembly by the electrical lead frame (B)

Note: Removing the manifold will be easier if you have an assistant hold the wiring harnesses out of the way.

Installation

Note: The mating surfaces of the cylinder heads, block and manifold must be perfectly clean when the manifold is installed.

12. Carefully remove all traces of old gasket material. Note that the intake manifold is made of a composite material and the cylinder heads on some engines are made of aluminum; therefore, aggressive scraping is not suggested and will damage the sealing surfaces. After the gasket surfaces are cleaned and free of any gasket material, wipe the mating surfaces with a cloth saturated with safety solvent. If there is old sealant or oil on the mating surfaces when the manifold is installed, oil or vacuum leaks may develop. Use a vacuum cleaner to remove any gasket material that falls into the intake ports in the heads.

13. Position the new gasket on the cylinder block then installs the VLOM, if removed, and tighten the bolts to the torque listed in this Chapter’s Specifications.

Warning: Wear safety glasses or a face shield to protect your eyes when using compressed air.

14. Position the new gaskets on the intake manifold. Note that the gaskets are equipped with installation tabs that must snap into place on the intake manifold. The words «Manifold Side» may appear on the gasket. If so, this will ensure proper installation. Make sure the gaskets snap into place and all intake port openings align.

15. Carefully set the manifold in place.

16. Install the bolts and tighten them following the recommended sequence (see illustration) to the torque listed in this Chapter’s Specifications. Do not overtighten the bolts or gasket leaks may develop.

7.16 Intake manifold bolt tightening sequence

Chevrolet Silverado V6 engine 4,3L _ Intake manifold bolt tightening sequence

17. The remainder of installation is the reverse of removal. Start the engine and check carefully for vacuum leaks at the intake manifold joints.

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