Hummer H2. Manual — part 1887

Fig. 694: The 6.0 Liter V8 Engine
Courtesy of GENERAL MOTORS CORP.

The 6.0 Liter V8 engine is identified as RPO LQ4 VIN U.

Camshaft and Drive System

A billet steel one piece camshaft is supported by five bearings pressed into the engine block. The camshaft has a
machined camshaft sensor reluctor ring incorporated between the fourth and fifth bearing journals. The
camshaft timing sprocket is mounted to the front of the camshaft and is driven by the crankshaft sprocket
through the camshaft timing chain. The splined crankshaft sprocket is positioned to the crankshaft by a key and
keyway. The crankshaft sprocket splines drive the oil pump driven gear. A retaining plate mounted to the front
of the engine block maintains camshaft location.

Crankshaft

The crankshaft is cast nodular iron. The crankshaft is supported by five crankshaft bearings. The bearings are

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2

retained by crankshaft bearing caps which are machined with the engine block for proper alignment and
clearance. The crankshaft journals are undercut and rolled. The center main journal is the thrust journal. A
crankshaft position reluctor ring is press fit mounted at the rear of the crankshaft. The reluctor ring is not
serviceable separately. All crankshafts will have a short rear flange, at the crankshaft rear oil seal area.

Cylinder Heads

The cylinder heads are cast aluminum and have pressed in place powdered metal valve guides and valve seats.
Passages for the engine coolant air bleed system are at the front of each cylinder head. The valve rocker arm
covers are retained to the cylinder head by four center mounted rocker arm cover bolts.

Engine Block

The engine block is a cam-in-block deep skirt 90 degree V configuration with five crankshaft bearing caps. The
engine block is cast iron. The five crankshaft bearing caps each have four vertical M10 and two horizontal M8
mounting bolts. The camshaft is supported by five camshaft bearings pressed into the block. First design engine
blocks have different drill and tap depths using both medium length 100 mm (3.94 in) and long 155 mm (6.1 in)
M11 cylinder head bolts. Second design engine blocks use only the medium length 100 mm (3.94 in) bolt with a
common drill and tap depth.

Exhaust Manifolds

The exhaust manifolds are a one piece cast iron design. The exhaust manifolds direct exhaust gasses from the
combustion chambers to the exhaust system. Each manifold also has an externally mounted heat shield that is
retained by bolts.

Intake Manifold

The intake manifold is a one piece composite design that incorporates brass threaded inserts for mounting the
fuel rail, throttle body, evaporative emission (EVAP) solenoid, wire harness stud, engine sight shield and sight
shield bracket. Each side of the intake manifold is sealed to the cylinder head by a nonreusable silicone sealing
gasket and nylon carrier assembly. The electronically actuated throttle body bolts to the front of the intake
manifold. The throttle body is sealed by a one piece push in place silicone gasket. The fuel rail assembly with
eight separate fuel injectors is retained to the intake by four bolts. The injectors are seated into their individual
manifold bores with O-ring seals to provide sealing. A fuel rail stop bracket is retained to the rear of the left
cylinder head by a mounting bolt. The manifold absolute pressure (MAP) sensor is installed and retained to the
top rear of the intake manifold and sealed by an O-ring seal. The EVAP solenoid is mounted to the top front of
the intake manifold and retained by one bolt. There are no coolant passages within the intake manifold.

Oil Pan

The structural oil pan is cast aluminum. Incorporated into the design are the oil filter mounting boss, drain plug
opening, oil level sensor mounting bore, and oil pan baffle. The oil pan transfer cover and oil level sensor
mount to the sides of the oil pan. The alignment of the structural oil pan to the rear of the engine block and
transmission bell housing is critical.

Piston and Connecting Rod Assembly

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2

The pistons are cast aluminum. The pistons use 2 compression rings and a 3-piece oil control ring assembly.
The piston is a low friction, lightweight design with a barrel shaped skirt. All applications use pistons with
graphite-coated skirts. The piston pins are chromium steel. First design applications use a piston pin that is
floating fit to the piston and press fit to the connecting rod. Second design applications use a pin that is full-
floating to both the piston and connecting rod. The connecting rods are powdered metal. The connecting rods
are fractured at the connecting rod journal and then machined for the proper clearance. The first design piston,
pin, and connecting rod are to be serviced as an assembly.

Valve Rocker Arm Cover Assemblies

The valve rocker arm covers are cast aluminum and use a pre-molded silicon gasket for sealing. Mounted to
each rocker cover are the coil and bracket assemblies. Incorporated into the left cover is the positive crankcase
ventilation (PCV) system passage. Incorporated into the right cover is the oil fill tube and engine fresh air
passage.

Valve Train

Motion is transmitted from the camshaft through the hydraulic roller valve lifters and tubular pushrods to the
roller type rocker arms. The nylon valve lifter guides position and retain the valve lifters. The valve rocker arms
for each bank of cylinders are mounted on pedestals, pivot supports. Each rocker arm is retained on the pivot
support and cylinder head by a bolt. Valve lash is net build.

NEW PRODUCT INFORMATION

The purpose of New Product Information is to highlight or indicate important product changes from the
previous model year.

Changes may include one or more of the following items:

z

Torque values and/or fastener tightening strategies

z

Changed engine specifications

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New sealants and/or adhesives

z

Disassembly and assembly procedure revisions

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Engine mechanical diagnostic procedure revisions

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New special tools required

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A component comparison from the previous year

Torque Values and/or Fastener Tightening Strategies

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All fasteners and threaded holes on the 6.0 liter engine utilize metric threads.

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Cylinder head, connecting rod, crankshaft balancer, and main bearing cap bolts now apply a torque angle
strategy.

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Certain fasteners should not be reused. Bolts, studs, or other fasteners that must be replaced will be called
out in the specific service procedure.

z

First design engine blocks cylinder head bolts have different torque/angle specifications using both

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2

medium length 100 mm (3.94 in) and long 155 mm (6.1 in) M11 cylinder head bolts. Second design
engine blocks use only the medium length 100 mm (3.94 in) bolt with a common torque/angle
specification.

z

Refer to Fastener Tightening Specifications and Thread Repair Specifications .

Disassembly and Assembly Procedure Revisions

z

Disassembly of the piston, press fit design piston pin, and connecting rod may create scoring or damage
to the piston pin and piston pin bore.

z

The piston, pin, and connecting rod are to be serviced as an assembly.

z

Newer design pistons have a graphite coated piston skirt. The coated skirt outside diameter (OD) may be
slightly larger than the cylinder bore inside diameter (ID) and the piston assembly may have a slight
interference fit to the cylinder bore during initial installation.

Engine Mechanical Diagnostic Procedure Revisions

All diagnosis on a vehicle should follow a logical process. Strategy based diagnostics is a uniform approach for
repairing all systems. The diagnostic flow may always be used in order to resolve a system problem. The
diagnostic flow is the place to start when repairs are necessary. For a detailed explanation, refer to Strategy
Based Diagnosis in General Information or Diagnostic Starting Point - Engine Mechanical .

New Special Tools Required

Angle Meter J 45059 has been developed to provide technicians with a convenient method to tighten bolts that
require the torque angle tightening strategy. See Special Tools and Equipment .

A Component Comparison from the Previous Year

z

Exhaust gas recirculation (EGR) system has been deleted on all applications.

z

All 2004 applications use a piston with a graphite-coated skirt.

z

The positive crankcase ventilation (PCV) valve is a non-serviceable fitting in the left rocker arm cover.

z

The fuel rails for all engines are returnless fuel systems. The fuel pressure regulator is now a part of the
fuel pump module.

z

First design applications use a piston pin that is floating fit to the piston and press fit to the connecting
rod. Second design applications use a piston pin that is full-floating to both the piston and connecting rod.

z

The first design piston, pin, and connecting rod are to be serviced as an assembly.

LUBRICATION DESCRIPTION

Lubrication Flow Schematic

2004 Hummer H2

2004 ENGINE Engine Mechanical - 4.8L, 5.3L, and 6.0L - Hummer H2