Chevrolet Silverado / GMC Sierra. Manual — part 1884

CAMSHAFT POSITION ACTUATOR AND SOLENOID VALVE DIAGNOSIS AND TESTING

1. Measure the engine oil level. Fill, as required.

2. Using the scan tool, inspect for diagnostic codes within the engine control module (ECM).

Refer to Diagnostic System Check - Vehicle . Repair, as required.

3. Verify proper engine oil pressure and operation of the active fuel management oil pressure

relief valve. Refer to Oil Pressure Diagnosis and Testing.

4. Inspect the CMP actuator solenoid valve for proper operation. Refer to Camshaft Position

Actuator Solenoid Valve Inspection (On-Vehicle) or Camshaft Position Actuator
Solenoid Valve Inspection (Off-Vehicle) .

If valve inspection confirms proper movement of the spool, replace the CMP actuator
and CMP valve.

If valve inspection confirms improper movement of the spool, replace only the CMP
valve.

5. Verify proper operation of the CMP actuator control system. Refer to Diagnostic Starting

Point - Engine Controls .

OIL LEAK DIAGNOSIS

IMPORTANT: Camshaft Position (CMP) Actuator and Solenoid Valve

Diagnosis and Testing is applicable for RPO LY6/L76/L92.

Step

Action

Yes

No

IMPORTANT:

You can repair most fluid leaks by first visually locating the leak, repairing or replacing the
component, or by resealing the gasket surface. Once the leak is identified, determine the cause of
the leak. Repair the cause of the leak as well as the leak itself.

1

1. Operate the vehicle until it reaches normal

operating temperature.

2. Park the vehicle on a level surface, over a

large sheet of paper or other clean surface.

3. Wait 15 minutes.

4. Inspect for drippings.

Are drippings present?

Go to Step 2

System OK

2

Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

Go to Step 3

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

3

1. Visually inspect the suspected area. Use a

small mirror to assist in looking at hard to
see areas.

2. Inspect for leaks at the following locations:

Sealing surfaces

Fittings

Cracked or damaged components

Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

Go to Step 4

4

1. Completely clean the entire engine and

surrounding components.

2. Operate the vehicle for several kilometers,

miles, at normal operating temperature and
at varying speeds.

3. Park the vehicle on a level surface, over a

large sheet of paper or other clean surface.

4. Wait 15 minutes.

5. Identify the type of fluid, and the

approximate location of the leak.

Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

Go to Step 5

5

1. Visually inspect the suspected area. Use a

small mirror to assist in looking at hard to
see areas.

2. Inspect for leaks at the following locations:

Sealing surfaces

Fittings

Cracked or damaged components

Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

Go to Step 6

1. Completely clean the entire engine and

surrounding components.

2. Apply an aerosol-type powder, baby

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

6

powder, foot powder, etc., to the suspected
area.

3. Operate the vehicle for several kilometers,

miles, at normal operating temperature and
at varying speeds.

4. Identify the type of fluid, and the

approximate location of the leak, from the
discolorations in the powder surface.

Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

Go to Step 7

7

1. Visually inspect the suspected area. Use a

small mirror to assist in looking at hard to
see areas.

2. Inspect for leaks at the following locations:

Sealing surfaces

Fittings

Cracked or damaged components

Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

Go to Step 8

8

Use the J 28428-E high-intensity black light kit
in order to identify the type of fluid, and the
approximate location of the leak. Refer to the
manufacturer's instructions when using the tool.
Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

Go to Step 9

9

1. Visually inspect the suspected area. Use a

small mirror to assist in looking at hard to
see areas.

2. Inspect for leaks at the following locations:

Sealing surfaces

Fittings

Cracked or damaged components

Can you identify the type of fluid and the
approximate location of the leak?

Go to Step 10

System OK

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado

CRANKCASE VENTILATION SYSTEM INSPECTION/DIAGNOSIS

10

1. Inspect the engine for mechanical damage.

Special attention should be shown to the
following areas:

Higher than recommended fluid levels

Higher than recommended fluid
pressures

Plugged or malfunctioning fluid filters
or pressure bypass valves

Plugged or malfunctioning engine
ventilation system

Improperly tightened or damaged
fasteners

Cracked or porous components

Improper sealants or gaskets, where
required

Improper sealant or gasket installation

Damaged or worn gaskets or seals

Damaged or worn sealing surfaces

2. Inspect the engine for customer

modifications.

Is there mechanical damage, or customer
modifications to the engine?

Go to Step 11

System OK

11

Repair or replace all damaged or modified
components.
Does the engine still leak oil?

Go to Step 1

System OK

Symptom

Correction

External oil leak

Inspect for any of the following conditions:

Restricted or kinked PCV hose or engine vent hose

Damaged, incorrect, or incorrectly installed PCV hose

Excessive crankcase pressure

Rough Idle

Inspect for any of the following conditions:

2008 Chevrolet Silverado 1500

2008 ENGINE Engine Mechanical - 4.8L, 5.3L, 6.0L, 6.2L, or 7.0L - Cab & Chassis Sierra, Cab & Chassis Silverado,

Sierra & Silverado