Chevrolet Silverado / GMC Sierra. 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