Chevrolet Silverado / GMC Sierra. Service manual — part 405

the drop of oil on the towel. The fuel will expand out in a ring around the oil droplet.

3. If fuel dilution is apparent, refer to Fuel Leak Diagnosis for diagnosis and repair. Inspect

the vehicle for aftermarket performance accessories that may cause damage to the injection
pump. After repairs are completed, perform the test again to verify the condition is
corrected.

4. If no fuel dilution is present, verify the oil level and correct as needed.

TURBOCHARGER WHINE NOISE

TURBOCHARGER HISSING NOISE

Condition

Action

Some whine noise is normal. Compare to a known good vehicle.
Leaking charge air cooler/pipes/hoses

Inspect for leaks in charge air
cooler/pipes/hoses using J 46091 .

Worn turbocharger bearings

Visually inspect for evidence of compressor
wheel to housing contact.
If the turbocharger bearings are worn or
damaged, inspect for a Turbocharger Lack
of Oil Supply.

Intake system leaks or obstructions

1. With the engine off, pressurize the

intake system using J 46091 and inspect
for intake manifold leaks.

2. Inspect for obstructions in the intake

manifolds.

Condition

Action

Air inlet leaks or obstructions

Inspect for leaks or obstructions in the
turbocharger inlet pipes/hoses.

Leaking charge air cooler/pipes/hoses

Inspect for leaks or obstructions in the charge
air cooler/pipes/hoses using J 46091 .

Leaking or restricted exhaust system

1. Inspect for a leak in the exhaust system.

2. Inspect for a restricted exhaust system.

Intake system leaks or obstructions

1. With the engine off, pressurize the

intake system using J 46091 and inspect
for intake manifold leaks.

2. Inspect for obstructions in the intake

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 6.6L - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

TURBOCHARGER OIL LEAK FROM COMPRESSOR SEAL

TURBOCHARGER OIL LEAK FROM TURBINE SEAL

TURBOCHARGER LACK OF OIL SUPPLY

manifolds.

Condition

Action

IMPORTANT:

Oil in the turbocharger air inlet duct,oil on the compressor wheel, and oil throughout the charge air
cooler system is normal with a closed PCV system. Do not attempt repairs for this condition.

Restricted air system

Inspect for clogged air filter element or
restricted air inlet system.

Restricted exhaust system

Inspect for a restricted exhaust.

Leaking exhaust system.

Inspect for exhaust manifold leaks.

Poor oil drainage from turbocharger

Inspect for restricted turbocharger oil drain
pipe.

Restricted crankcase ventilation system

Inspect for restricted crankcase ventilation
system.

Worn internal engine components

Inspect for excessive blowby or engine oil
consumption.

Condition

Action

Poor oil drainage from turbocharger

Inspect for a restricted turbocharger oil drain
pipe.

Restricted crankcase ventilation system

Inspect for a restricted crankcase ventilation
system.

Worn internal engine components

Inspect for excessive blowby or engine oil
consumption.

Condition

Action

Restricted oil supply hose

Inspect for restricted turbocharger oil supply
hose.

Spun camshaft bearing

1. Remove the oil supply hose. Refer to

Turbocharger Oil Feed Pipe
Replacement .

2. Visually inspect for correct alignment of

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 6.6L - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

ENGINE COMPRESSION TEST

Tools Required

J 26999 Compression Gage. See Special Tools.

EN-47603 Compression Gage Adapter. See Special Tools.

Test

1. Ensure that the vehicle's batteries are in good condition, and fully charged.

2. Operate the vehicle until the engine is at normal operating temperature.

3. Shut off engine.

4. Disconnect the crankshaft position sensor.

5. Disconnect glow plug nut; remove all 8 glow plugs. All 8 glow plugs must be removed from

the engine during each cylinder test to obtain valid test results.

6. Prior to taking a compression reading, verify the cranking speed is greater than 140 RPM. If

the cranking speed is below 140 RPM, repair the slow cranking speed condition before
continuing with the compression test. Refer to Engine Cranks Slowly .

7. Install the EN-47603 in the glow plug hole for the cylinder that is being checked. See

Special Tools.

the camshaft bearing oil hole.

3. Rotate the engine 1/2 turn and inspect

the camshaft bearing oil hole for
movement, indicating a spun camshaft
bearing.

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 6.6L - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado

Fig. 44: View Of J 26999 For A Compression Test
Courtesy of GENERAL MOTORS CORP.

8. Connect the J 26999 to the EN-47603 . See Special Tools.

9. Using the vehicle's starter motor, rotate or crank the engine for 6 compression strokes, puffs,

NOTE:

Do not add oil to any cylinder during a compression test as
extensive engine damage may result.

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 6.6L - Cab & Chassis Sierra, Cab & Chassis Silverado, Sierra & Silverado