Chevrolet Silverado / GMC Sierra. Manual — part 1899
kPa (55 psi), the oil pressure relief valve exhausts excess oil to the sump.
Oil is then directed from the filter to the upper main oil galleries and the valve lifter oil manifold
assembly. Oil from the left upper oil gallery is directed to the crankshaft and camshaft bearings.
Oil that has entered both the upper main oil galleries also pressurizes the valve lifter assemblies
and is then pumped through the pushrods to lubricate the valve rocker arms and valve stems. Oil
returning to the pan is directed by the crankshaft oil deflector. The oil pressure sensor is located
at the top rear of the engine.
With active fuel management activated, the engine control module (ECM) commands the 4
solenoids to open, directing oil through the engine block oil galleries to the intake and exhaust
valve lifters for cylinders 1, 4, 6, and 7. Refer to Cylinder Deactivation (Active Fuel
Management) System Description.
LUBRICATION DESCRIPTION - MAIN PRESSURE ABOVE 55 PSI WITH CYLINDER
DEACTIVATION (ACTIVE FUEL MANAGEMENT) ON (RPO L76)
2008 Chevrolet Silverado 1500
2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
Fig. 58: Lubrication Schematic Above 55 psi (RPO L76)
Courtesy of GENERAL MOTORS CORP.
Engine lubrication is supplied by a gerotor type oil pump assembly. The oil pump is mounted on
the front of the engine block and driven directly by the crankshaft sprocket. The pump gears
rotate and draw oil from the oil pan sump through a pick-up screen and pipe. The oil is
pressurized as it passes through the pump and is sent through the engine block lower oil gallery.
Contained within the oil pump assembly is a pressure relief valve that maintains oil pressure
within a specified range.
Pressurized oil is directed through the engine block lower oil gallery to the full flow oil filter
where harmful contaminants are removed. A bypass valve is incorporated into the oil filter, which
permits oil flow in the event the filter becomes restricted. A second valve, the active fuel
management oil pressure relief valve is incorporated into the oil pan. The active fuel management
oil pressure relief valve limits oil pressure directed to the upper oil galleries and valve lifter oil
manifold assembly to 379-517 kPa (55-75 psi) maximum. When main oil pressure exceeds 379
kPa (55 psi), the oil pressure relief valve exhausts excess oil to the sump.
Oil is then directed from the filter to the upper main oil galleries and the valve lifter oil manifold
assembly. Oil from the left upper oil gallery is directed to the crankshaft and camshaft bearings.
Oil that has entered both the upper main oil galleries also pressurizes the valve lifter assemblies
and is then pumped through the pushrods to lubricate the valve rocker arms and valve stems.
An oil passage at camshaft bearing location 2 permits oil flow into the center of the camshaft. Oil
enters the camshaft exiting at the front and into the camshaft position (CMP) actuator solenoid
valve. The CMP valve spool position is controlled by the engine control module (ECM) and
CMP magnet. When commanded by the ECM, the CMP magnet repositions the CMP actuator
solenoid valve spool directing pressurized oil into the CMP actuator to control valve timing.
Refer to Camshaft Actuator System Description .
Oil returning to the pan is directed by the crankshaft oil deflector. The oil pressure sensor is
located at the top rear of the engine.
With active fuel management activated, the ECM commands the 4 solenoids to open, directing oil
through the engine block oil galleries to the intake and exhaust valve lifters for cylinders 1, 4, 6,
and 7. For RPO L99, active fuel management hardware is present in first design engines. The
system is inactive for the 2007 model year. Refer to Cylinder Deactivation (Active Fuel
Management) System Description and Camshaft Position Actuator and Solenoid Valve
Description.
CLEANLINESS AND CARE
2008 Chevrolet Silverado 1500
2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
Throughout this section, it should be understood that proper cleaning and protection of
machined surfaces and friction areas is part of the repair procedure. This is considered
standard shop practice, even if not specifically stated.
When any internal engine parts are serviced, care and cleanliness is important.
When components are removed for service, they should be marked, organized or retained in
a specific order for assembly. Refer to Separating Parts.
At the time of installation, components should be installed in the same location and with the
same mating surface as when removed.
An automobile engine is a combination of many machined, honed, polished and lapped
surfaces with tolerances that are measured in millimeters or thousandths of an inch. These
surfaces should be covered or protected to avoid component damage.
A liberal coating of clean engine oil should be applied to friction areas during assembly.
Proper lubrication will protect and lubricate friction surfaces during initial operation.
SEPARATING PARTS
Separate, mark, or organize the following components:
Piston and the piston pin
Piston to the specific cylinder bore
Piston rings to the piston
Connecting rod location and orientation to the crankshaft journal
Connecting rod to the bearing cap
A paint stick or etching/engraving type tool are recommended. Stamping the connecting rod
or cap near the bearing bore may affect component geometry.
Crankshaft main and connecting rod bearings
Camshaft and valve lifters
Valve lifters, lifter guides, pushrods and rocker arm assemblies
Valve to the valve guide
IMPORTANT:
Many internal engine components will develop specific wear
patterns on their friction surfaces.
When disassembling the engine, internal components MUST
be separated, marked, or organized in a way to ensure
installation to their original location and position.
2008 Chevrolet Silverado 1500
2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
Valve spring to the cylinder head location
Engine block main bearing cap location and direction
Oil pump drive and driven gears
REPLACING ENGINE GASKETS
Tools Required
J 28410 Gasket Remover
Gasket Use and Applying Sealants
Do not use any gasket again unless specified.
Gaskets that can be used again will be identified in the service procedure.
Do not apply sealant to any gasket or sealing surface unless called out in the service
information.
Separating Components
Use a rubber mallet to separate components.
Bump the part sideways to loosen the components.
Bumping should be done at bends or reinforced areas to prevent distortion of parts.
Cleaning Gasket Surfaces
Remove all gasket and sealing material from the part using the J 28410 or equivalent.
Care must be used to avoid gouging or scraping the sealing surfaces.
Do not use any other method or technique to remove sealant or gasket material from a part.
Do not use abrasive pads, sand paper, or power tools to clean the gasket surfaces.
These methods of cleaning can cause damage to the component sealing surfaces.
Abrasive pads also produce a fine grit that the oil filter cannot remove from the oil.
This grit is abrasive and has been known to cause internal engine damage.
Assembling Components
When assembling components, use only the sealant specified or equivalent in the service
procedure.
NOTE:
Refer to Sealant Notice .
2008 Chevrolet Silverado 1500
2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,
Sierra & Silverado
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