Hummer H1 (2006+). Manual - part 24
2-2
Engine
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ENGINE DESCRIPTION
A turbocharged diesel engine is used in the HUMMER H1 vehicles. It is a liquid cooled, four-stroke, 90° – V8 engine with a dis-
placement of 6.6L (402 cu. in.) (Figure 2-1). The engine is manufactured by Duramax Inc. (GM / Isuzu).
Figure 2-1: 6.6L Turbo Diesel Engine
Engine Components
The engine block is grey iron and the cylinder heads are aluminum. Turbo engines are equipped with a three-piece aluminum in-
take manifold and cast iron exhaust manifolds.
The oil cooling system for turbo diesel pistons provides for oil spray onto the underside of the piston crown. This is accomplished
by additional oil feed orifice tubes and galleries in the block. Oil spray occurs when the piston is approaching bottom dead center
on the intake and power strokes. The extra oil pressure and volume needed for piston cooling is provided by a high output oil
pump. The pump has a working pressure of 55 to 60 psi at 3250 RPM. Oil feed for piston spray is through galleries and oil tubes lo-
cated in the main bearing saddles and webs.
The crankshaft is supported by five insert style main bearings. The camshaft is also supported by five bearings; plain type bearings
are used.
The engine is equipped with three ring aluminum pistons. Connecting rods are forged steel. The pistons are attached to the rods
with hardened steel piston pins. Each piston pin is retained by two snap rings; one at each end of the pin. The pin is a floating fit in
the rod and piston.
A gear driven camshaft operates the overhead valve train. Roller lifters and tubular push rods actuate the rocker arms. The arms are
mounted on shafts bolted to each cylinder head.
The cylinder heads are equipped with glow plugs for each cylinder and a prechamber for each combustion chamber. One plug and
one prechamber are used in each combustion chamber. The glow plugs heat the air entering the prechamber. This aids the combus-
tion process and improves cold weather starting and operation. The glow plugs are activated only when ambient temperatures fall
below a pre-set value. On the turbo diesel engine the glow plug relay is mounted on the intake manifold and is controlled by the
ECM.
The turbocharged diesel engine is equipped with an IHI turbocharger. Vanes in the turbine housing control the boost. The position
of the vanes is variable and controlled by a vain position solenoid based on information sent to the ECM by the boost sensor. The
vane position is monitored by the vane position sensor. This allows a proportionate increase in fuel injected into the cylinders. The
result is a much denser cylinder charge and greater power output.
The turbocharger turbine and compressor impellers are the mechanisms that pump additional air into the combustion chambers.
The impeller wheels are operated by the high speed gas flow through the engine exhaust system.
Engine lubrication is through a conventional mechanical pump located at the rear of the crankcase. The pump is shaft driven by the
oil pump drive unit which in turn, is driven off the camshaft. The 6.6L diesel is equipped with a high pressure fuel injection system.
The system consists of an electric fuel supply pump, an injection pump, a separate injector nozzle for each cylinder, and the neces-
sary injector feed lines.