Visual Inspection

Camshaft Thrust Washers (If Equipped)

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the camshaft thrust washers for deep scoring or uneven wear (1).

2. Replace as necessary.

Camshaft Position Actuators

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the front of the exhaust camshaft position actuators for the following:

   • Sprocket damage (1)
   • Reluctor/sensor wheel damage (2)
   • Camshaft position actuator bolt seating/sealing inner hub flange damage (3)

2. Courtesy of GENERAL MOTORS COMPANY

   Inspect the back of the exhaust camshaft position actuators for the following:

   • Sprocket damage (1)
   • Camshaft locating pin damage (2)
   • Camshaft seating/sealing inner hub flange damage (3)
   • Blockage to the oil passages (4)
   • Loose or missing housing bolts (5)

3. Courtesy of GENERAL MOTORS COMPANY

   Inspect the front of the left intake camshaft position actuators for the following:

   • Sprocket damage (1)
   • Reluctor/sensor wheel damage (2)
   • Camshaft position actuator oil control valve bolt seating/sealing inner hub flange damage (3)

4. Courtesy of GENERAL MOTORS COMPANY

   Inspect the back of the left intake camshaft position actuators for the following:

   • Sprocket damage (1)
   • Camshaft locating pin damage (2)
   • Camshaft seating/sealing inner hub flange damage (3)
   • Blockage to the oil passages (4)
   • Loose or missing housing bolts (5)

5. Courtesy of GENERAL MOTORS COMPANY

   Inspect the front of the right intake camshaft position actuators for the following:

   • Sprocket damage (1)
   • Reluctor/sensor wheel damage (2)
   • Camshaft position actuator oil control valve bolt seating/sealing inner hub flange damage (3)

6. Courtesy of GENERAL MOTORS COMPANY

   Inspect the back of the right intake camshaft position actuators for the following:

   • Sprocket damage (1)
   • Camshaft locating pin damage (2)
   • Camshaft seating/sealing inner hub flange damage (3)
   • Blockage to the oil passages (4)
   • Loose or missing housing bolts (5)
7. Replace a damaged camshaft position actuator.

Camshaft Position Actuator Oil Control Valves

1. Fig 1: Identifying Camshaft Position Actuator Oil Control Valves Inspection Areas (LF4)

   Courtesy of GENERAL MOTORS COMPANY

   Inspect the camshaft position actuator oil control valves for the following:

   • Blockage to the oil passage (1)
   • Missing or damaged oil screen clip (2)
   • Blockage or damage to the oil screen (3)
   • Damage to the sealing surface for the camshaft position actuator oil control valve solenoid oil seal (4)
   • Damage to the bracket (5)
   • Damage to the wiring harness connection and/or terminals (6)
2. Replace a damaged camshaft position actuator oil control valve.

Left Intermediate Sprocket with Primary and Secondary Inverted Tooth (IT) Chain

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the front of the left intermediate sprocket for the following:

   • Damage to the primary camshaft drive chain sprocket (1)
   • Damage to the hub bearing (2) - Ensure the hub bearing spins freely. If the hub bearing wobbles, is noisy, or feels rough when rotated, replace the intermediate sprocket.
   • Damage to the bolt flange seating/sealing surface (3)

2. Courtesy of GENERAL MOTORS COMPANY

   Inspect the back of the left intermediate sprocket for the following:

   • Damage to the left secondary camshaft drive chain sprocket (1)
   • Damage to the bearing hub-to-engine block sealing surface (2)
3. Replace a damaged left intermediate sprocket.

Right Intermediate Sprocket with Primary and Secondary Inverted Tooth (IT) Chain

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the front of the right intermediate sprocket for the following:

   • Damage to the right secondary camshaft drive chain sprocket (1)
   • Damage to the hub bearing (2) - Ensure the hub bearing spins freely. If the hub bearing wobbles, is noisy, or feels rough when rotated, replace the intermediate sprocket.
   • Damage to the bolt flange seating/sealing surface (3)

2. Courtesy of GENERAL MOTORS COMPANY

   Inspect the back of the right intermediate sprocket for the following:

   • Damage to the primary camshaft drive chain sprocket (1)
   • Damage to the bearing hub-to-engine block sealing surface (2)
3. Replace a damaged right intermediate sprocket.

Crankshaft Sprocket with Second Version Primary Inverted Tooth (IT) Chain

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the crankshaft sprocket for the following:

   • Sprocket damage (1)
   • Bore damage (2)
   • Keyway damage (3)
2. Replace a damaged crankshaft sprocket.

Secondary Timing Chains with Inverted Tooth (IT) Chain

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the secondary timing chain for the following:

   • Binding or worn links (1)
   • Loose links (2)
   • Loose pins (3)
2. Replace a damaged secondary timing chain.

Primary Timing Chain with Inverted Tooth (IT) Chain

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the primary timing chain for the following:

   • Binding or worn links (1)
   • Loose links (2)
   • Loose pins (3)
2. Replace a damaged primary timing chain.

Primary Timing Chain Upper Guide

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the primary timing chain upper guide for the following:

   • Worn guide surface (1)
   • Cracked or broken guide surface (2)
   • Cracked or damaged guide base (3)
2. Replace a damaged primary timing chain upper guide.

Primary Timing Chain Lower Guide

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the primary timing chain lower guide for the following:

   • Worn guide surface (1)
   • Cracked or broken guide surface (2)
   • Cracked or damaged guide base (3)
2. Replace a damaged primary timing chain lower guide.

Left Secondary Timing Chain Guide

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the left secondary timing chain guides for the following:

   • Worn guide surface (1)
   • Cracked or broken guide surface (2)
   • Cracked or damaged guide base (3)
2. Replace a damaged left secondary timing chain guide.

Right Secondary Timing Chain Guide

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the right secondary timing chain guides for the following:

   • Worn guide surface (1)
   • Cracked or broken guide surface (2)
   • Cracked or damaged guide base (3)
2. Replace a damaged right secondary timing chain guide.

Left Secondary Timing Chain Shoe

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the front of the left secondary timing chain shoe for the following:

   • Worn shoe surface (1)
   • Cracked or broken shoe surface (2)
   • Cracked or damaged shoe (3)

2. Courtesy of GENERAL MOTORS COMPANY

   Inspect the back of the left secondary timing chain shoe for a damaged, worn, or missing left secondary timing chain tensioner contact pad (1).

3. Replace a damaged left secondary timing chain shoe.

Right Secondary Timing Chain Shoe

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the front of the right secondary timing chain shoe for the following:

   • Worn shoe surface (1)
   • Cracked or broken shoe surface (2)
   • Cracked or damaged shoe (3)

2. Courtesy of GENERAL MOTORS COMPANY

   Inspect the back of the right secondary timing chain shoe for a damaged, worn, or missing right secondary timing chain tensioner contact pad (1).

3. Replace a damaged right secondary timing chain shoe.

Primary Timing Chain Tensioner

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the primary timing chain tensioner for worn primary timing chain tensioner shoe surface (1).

2. Inspect the primary timing chain tensioner for locked or binding timing chain tensioner. Reset the plunger (3) and ensure the plunger moves freely (2) in and out of the body of the tensioner. Refer to Camshaft Timing Chain Components Installation (LF4) .
3. Replace a damaged primary timing chain tensioner.

Left Secondary Timing Chain Tensioner

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the left secondary timing chain tensioner for damaged plunger-to-shoe contact surface (1).

2. Inspect the left secondary timing chain tensioner for locked or binding timing chain tensioner. Reset the plunger (3) and ensure the plunger moves freely (2) in and out of the body of the tensioner. Refer to Camshaft Timing Chain Components Installation (LF4) .
3. Replace a damaged left secondary timing chain tensioner.

Right Secondary Timing Chain Tensioner

1. Courtesy of GENERAL MOTORS COMPANY

   Inspect the right secondary timing chain tensioner for damaged plunger-to-shoe contact surface (1).

2. Inspect the right secondary timing chain tensioner for locked or binding timing chain tensioner. Reset the plunger (3) and ensure the plunger moves freely (2) in and out of the body of the tensioner. Refer to Camshaft Timing Chain Components Installation (LF4) .
3. Replace a damaged right secondary timing chain tensioner.