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Hummer H1 (2002+). Manual - part 13

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Engine 2-13

05745159

Excessive Oil
Consumption

Prolonged high speed, high load, or overload
operation.

Incorrect oil grade used for high ambient
temperature operation.

Oil leaks at:
¥ Rocker covers ¥Oil pan
¥ Rear main seal ¥Oil Þlter
¥ Timing chain cover or seal
¥ Cooler hoses/lines

CDR valve or hose faulty.

Engine problem:
¥ Worn broken piston rings

¥ Worn valve seats or guides

1. Reduce overload, or speed as needed.

2. Switch to SG, SH-CD oil with SAE viscosity rat-

ing of 15W-40, 20W-50, or 30W.

3. Locate and correct leaks as needed.

4. Check valve and hose and replace if necessary.

5. Run compression test to verify ring problem.

Overhaul cylinder heads if guides, seals, valves are
worn. If wear is premature, check injectors and
injection pump. Excessive fuel will wash oil off
walls/guides causing ring and valve wear.

Engine Vibration

NOTE

: See road

test information
in this section.

Loose engine accessories:

¥ Alternator
¥ A/C compressor
¥ Power steering pump
¥ Mounting brackets
¥ Pulleys
¥ Belt tensioner
¥ Serpentine belt
¥ Drive pulleys

Torsional damper damaged or loose.

Flywheel (driveplate) cracked or loose.

Torque converter imbalance caused by inter-
nal damage or missing balance weight.

1. Check and repair as needed. Replace damaged

missing bolts and apply Loctite 242 to loose bolt
threads. Replace serpentine belt if damaged.
Replace bent, broken pulleys.

2. Replace damper if damaged, worn, loose.

3. Replace ßywheel and also check for ballooned or

damaged converter.

4. Replace converter.

Overheating

Dirt, debris blocking air ßow through cool-
ers, condenser, and radiator.

Low coolant level.

Serpentine belt loose, worn, or tensioner
inoperative.

Prolonged idling/slow speed operation in
heavy trafÞc when ambient temperatures are
high.

1. Remove and clear Þns with compressed air, soft

bristle brush, or water stream.

2. Add coolant and check for leaks (hoses, surge

tank, hose connections, water pump, radiator).

3. Replace belt and/or tensioner if either part has

failed or is worn beyond limit.

4. If this type operation cannot be avoided, have

driver turn on heater and ÒrevÓ engine when
stopped in trafÞc. This will help dissipate some
heat and get more air through radiator (from fan).

Engine Diagnosis

PROBLEM

POTENTIAL CAUSE

CORRECTION

2-14

Engine

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Overheating
(continued)

Failed thermostat or radiator cap.

Fan clutch inoperative.

Water pump inoperative.

Blown head gasket.

Crack in block, or leaking freeze plug.

10. Coolant temperature gauge or sensor faulty.

5. Check thermostat and cap operation. Replace

either part if inoperative.

6. Replace clutch.

7. Check coolant ßow and replace pump if necessary.

8. Verify that coolant is leaking into combustion

chamber and replace gasket.

9. Replace corroded freeze plugs. Replace block if

cracked.

10. Test and replace gauges or sensors as needed.

High Fuel
Consumption

1. Prolonged high speed - high load operation.

2. Air cleaner/Þlter partially plugged.

3. Fuel leaks in lines, hoses at connections.

4. Restriction in exhaust system (should also be

accompanied by drop in power).

5. Decrease in boost on turbocharged models,

caused by vacuum leak at actuator, manifold
leak, or turbo damage.

6. Brake drag

7. Converter one way clutch failure.

8. Injection pump internal problem.

9. Power loss due to worn rings, valve guides,

cylinder bores, valves, etc.

1. Normal with this type of operation. Have driver

reduce speed or load if possible.

2. Remove and clean air horn, intake hose, air

cleaner. Replace Þlter.

3. Locate and repair as needed.

4. Inspect and replace bent, kinked, damaged compo-

nents.

5. Correct leaks. Replace actuator or turbocharger if

inoperative.

6. Repair stuck/seized calipers.

7. Replace converter.

8. Diagnose and replace as necessary.

9. Overhaul engine.

Engine Diagnosis

PROBLEM

POTENTIAL CAUSE

CORRECTION

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Engine 2-15

05745159

TURBOCHARGER SERVICE AND DIAGNOSIS

Description

The turbocharger used on 6.5L diesel engines is a Borg-
Warner model 1H1 (Figure 2-7). Lubrication is by engine oil
from the engine lubrication system.

Boost is monitored by the PCM and controlled by the waste-
gate and electronic accelerator pedal. The pedal assembly con-
sists of a bracket, pedal and arm, and the pedal position sensor
(potentiometer); a conventional throttle linkage is not used.

The turbocharger is mounted in the lifter valley at the rear of
the engine block. It is positioned between the two halves of the
intake manifold.

A turbocharger is fundamentally an air pump used to generate
additional engine power. This is accomplished by increasing
volume and pressure of air entering the engine combustion
chambers. An increase in air volume allows a proportional in-
crease in fuel injected into the cylinders. The net result is a
denser fuel/air mixture. A denser mixture produces more power
when compressed and burned in the combustion chamber.

A turbocharger feature concerns the method of operation. The
turbocharger turbine and compressor impellers are rotated by
the flow of engine exhaust gases. As a result, separate drive
belts and pulleys are not needed.

Figure 2-7: Turbocharger and Vacuum Actuator

Mounting

The turbocharger used on 6.5L engines consists of a turbine
impeller and housing, a compressor impeller and housing, a
wastegate, a wastegate actuator and an impeller connecting-
shaft (Figure 2-8). A separate, belt driven vacuum pump sup-
plies vacuum for wastegate actuator operation.

Figure 2-8: Turbocharger Components (Typical)

WASTEGATE

VACUUM

ACTUATOR

MANIFOLD

CROSSOVER

HOUSING

TURBOCHARGER

AIR OUTLET

(TO MANIFOLD)

COMPRESSOR HOUSING

AND IMPELLER

FRESH AIR INLET

(FROM AIR CLEANER)

WASTEGATE VACUUM ACTUATOR

TURBINE/COMPRESSOR

SHAFT

WASTEGATE

VALVE

LEVER

ROD

OUTLET

EXHAUST

AND IMPELLER

TURBINE HOUSING

2-16

Engine

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TURBOCHARGER OPERATION

The wastegate valve controls boost. It is operated by the vac-
uum actuator. Opening the valve stops boost and closing the
valve generates boost. Boost levels are continuously monitored
by the PCM.

In the operation, an increase in accelerator pedal sensor angle
to boost detent, causes the pedal sensor to signal the PCM that
engine load is increasing. At this point, the PCM closes the
wastegate valve with the actuator and increases fuel flow to the
injectors.

Closing the wastegate valve allows full exhaust gas flow into
the turbine housing. As the gas enters the housing, it acts
against the blades on the turbine impeller causing it to rotate.
Since the turbine and compressor impellers are fixed to the
same shaft, the turbine impeller causes the compressor impel-
ler to rotate as well.

Once the compressor impeller begins rotating, it draws fresh air
into the compressor housing. The air is then compressed and
pumped into the intake manifold. Fresh air source for the com-
pressor section is through the air cleaner and related ducting.

A decrease in pedal sensor angle signals the PCM that boost
can be reduced or stopped entirely. The PCM then opens the
wastegate valve by reducing vacuum to the actuator. Once
open, the wastegate causes exhaust gas to bypass the turbine
housing and impeller.

Electronic Accelerator Pedal

The electronic pedal is unique to models equipped with a turbo-
charged engine. It consists of a pedal, arm, and position sensor
(potentiometer), attached to a mounting bracket (Figure 2-9).

Figure 2-9: Electronic Accelerator Pedal

The position sensor is a potentiometer that operates like a TPS.
It signals pedal position to the PCM. At boost detent position,
the potentiometer signal causes the PCM to close the wastegate
valve and generate boost.

Turbocharger Service

The turbocharger is not a repairable component. It must be re-
placed as an assembly when diagnosis indicates this is necessary.

Wastegate Actuator Test

The actuator is tested with a hand operated vacuum pump.
Testing is performed with the engine off (not running) as fol-
lows:

Operate wastegate lever by hand. Lever should move back
and forth freely without bind or drag.

Disconnect vacuum line at actuator and connect vacuum
pump to actuator.

Apply 5 inches vacuum to actuator and note action.
Actuator rod should close wastegate smoothly. If rod fails
to move, release vacuum and proceed to next step.

Disconnect actuator rod at wastegate lever. Apply 5 inches
vacuum to actuator, and note rod operation. If rod fails to
move replace actuator. But if rod does move wastegate
valve or lever is binding. Free up lever with heat valve
lubricant. Replace turbocharger if wastegate valve is
seized or binding.

Boost Pressure Test

Boost pressure is checked with a compound vacuum/pressure
gauge. A road test under boost conditions is required. Proce-
dure is as follows:

Attach compound gauge hose to Þtting on air inlet tube, air
horn, or turbocharger outlet.

Route hose to passenger side-window and into vehicle
interior.

Road test vehicle. Have helper either drive or observe test
gauge. Press accelerator pedal to wide open position and
note gauge reading. A gauge reading of 2 psi (14 kPa) or
more indicates normal operation.

NOTE:

During deceleration, boost level may decrease, this is

normal.

If gauge reading is zero, or well below 2 psi (14 kPa),
check complete air intake and exhaust system for leaks
and repair as needed. Also check vacuum actuator, and
accelerator pedal potentiometer. Run electrical check with
Tech 2 scan tool if electrical system problems are
suspected.

Vacuum Pump Test

The pump can be checked with a standard vacuum gauge. Out-
put should be minimum of 20-21 inches vacuum.

PEDAL AND

ARM

MOUNTING

BRACKET

POSITION SENSOR

(POTENTIOMETER)

Content .. 11 12 13 14 ..