Chevrolet Silverado / GMC Sierra. Service manual — part 403

BASE ENGINE MISFIRE WITH EXCESSIVE OIL CONSUMPTION

ENGINE NOISE ON START-UP, BUT ONLY LASTING A FEW SECONDS

Cylinder Head or Engine Block Damage

3. Inspect the cylinder block to head

mating surface for straightness.

4. Replace components as necessary.

Condition

Action

Worn valve guides

1. Inspect the valves and valve guides.

2. Repair or replace all damaged

components.

Worn valve stem oil seals

1. Inspect the valve stem oil seals.

2. Repair or replace all damaged

components.

Excessive piston-to-cylinder bore clearance

1. Perform cylinder leak down and

compression tests to determine the
cause.

2. Inspect the piston rings for low ring

tension, broken or worn rings.

3. Inspect cylinder bore.

4. Repair or replace all damaged

components.

Condition

Action

Incorrect oil viscosity

1. Drain the oil.

2. Install the correct viscosity oil.

Excessive piston-to-cylinder bore clearance

1. Inspect the piston and piston skirt,

connecting rod, and cylinder bore.

2. Repair or replace all damaged

components.

Damaged or faulty oil filter by-pass valve

1. Inspect the oil filter by-pass valve for

proper operation.

2. Repair or replace as necessary.

2008 Chevrolet Silverado 1500

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

UPPER ENGINE NOISE, REGARDLESS OF ENGINE SPEED

Condition

Action

Low oil pressure

Insufficient or poor oil supply to valve train.

1. Perform oil pressure test.

2. Repair or replace all damaged

components.

Improper lubrication to the valve rocker
arms

1. Inspect valve rocker arm and shaft,

valve pushrod, oil filter bypass valve, oil
pump and pump screen, and engine
block oil galleries.

2. Repair or replace all damaged

components.

Excessive valve lash

1. Check the valve lash adjustment, and

correct if above specifications.

2. Repair or replace all damaged

components.

Worn pushrod upper end ball

1. Inspect pushrod end ball.

2. Repair or replace all damaged

components.

Bent valve pushrod

1. Inspect valve pushrod and valve rocker

arm.

2. Repair or replace all damaged

components.

Loose, worn or damaged valve rocker arm

1. Inspect valve rocker arm and rocker arm

shaft.

2. Repair or replace all damaged

components.

Loose valve rocker arm attachments

1. Inspect valve rocker arm and rocker arm

shaft.

2. Repair or replace all damaged

components.

Broken valve springs

1. Inspect valve springs.

2. Repair or replace all damaged

2008 Chevrolet Silverado 1500

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

LOWER ENGINE NOISE, REGARDLESS OF ENGINE SPEED

components.

Worn and/or damaged valve spring shims,
seats, or keys

1. Inspect valve spring shims, seats, and

keys.

2. Repair or replace all damaged

components.

Sticking valve

Carbon on the valve stem or valve seat may
cause the valve to stick.

1. Inspect valves and valve guides.

2. Repair or replace all damaged

components.

Missing or improperly positioned lifter
guides

1. Inspect lifter guides.

2. Repair or replace all damaged

components.

Worn or faulty camshaft lobes

1. Inspect camshaft lobes.

2. If damaged replace camshaft and all

lifters.

Worn valve guide

1. Inspect the valves and valve guides.

2. Repair or replace all damaged

components.

Damaged or misaligned timing gears

1. Inspect timing gears.

2. Replace all damaged components.

Condition

Action

Worn accessory drive components
(abnormalities such as severe cracking,
bumps or missing areas in the accessory drive
belt and/or misalignment of the system
components.)

1. Inspect the accessory drive components.

2. Repair or replace all damaged

components.

Low oil pressure

Insufficient or poor oil supply to crankshaft
and connecting rod bearings.

1. Perform oil pressure test.

2. Repair or replace all damaged

2008 Chevrolet Silverado 1500

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

components.

Leaking and/or sticking fuel injection nozzle
(A stuck fuel injection nozzle can cause a
noise similar to a damaged piston, rod or rod
bearing.)

1. Use the cylinder balance diagnostic

procedure to help locate the cylinder
that is the source of the noise.

2. If you cannot locate the cylinder that is

the source of the noise, diagnose the
engine for mechanical damage.

3. If it has been determined that the fuel

injection nozzle is causing the noise,
replace the fuel injection nozzle.

Loose and/or damaged crankshaft balancer

1. Inspect crankshaft balancer and

balancer bolt.

2. Repair or replace all damaged

components.

Loose torque converter bolts

1. Inspect torque converter bolts and

flywheel.

2. Repair or replace all damaged

components.

Loose and/or damaged flywheel

1. Inspect flywheel and flyweel attaching

bolts.

2. Repair or replace all damaged

components.

Excessive piston-to-cylinder bore clearance

1. Inspect the piston, piston rings and

cylinder bore.

2. Repair or replace all damaged

components.

Excessive piston pin-to-bore clearance

1. Inspect the piston, piston pin, and the

connecting rod.

2. Repair or replace all damaged

components.

Misaligned or bent connecting rod

1. Inspect connecting rod and connecting

rod bearings.

2. Repair or replace all damaged

components.

Excessive connecting rod bearing clearance

1. Inspect the connecting rod bearings,

2008 Chevrolet Silverado 1500

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