Chevrolet Silverado / GMC Sierra. Service manual — part 2134

reposition the reluctor wheel to the PARK position. Inspect for proper alignment of
the mark on the face of the sprocket (1) with the flat edge of the reluctor wheel (2). If
the reluctor wheel is not properly positioned, the internal components of the actuator
are sticking or the return spring is broken and the actuator should be replaced as an
assembly.

Nicked or damaged edges (3) on the CMP reluctor wheel

Damaged timing chain teeth (4)

Fig. 77: View Of Oil Passages
Courtesy of GENERAL MOTORS CORP.

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. Inspect the CMP actuator for dirt, debris, or restrictions within the oil passages (1, 2, 3).

Fig. 78: View Of Timing Chain Tensioner Inspection Points
Courtesy of GENERAL MOTORS CORP.

7. Inspect the timing chain tensioner for the following conditions:

Damaged or broken tension spring (1)

Excessive wear or scoring on the chain guide surfaces (2, 3)

CAMSHAFT POSITION ACTUATOR MAGNET CLEANING AND INSPECTION

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

Fig. 79: Measuring Retracted Position
Courtesy of GENERAL MOTORS CORP.

1. Inspect the CMP magnet for the following conditions:

A damaged electrical connector

An accumulation of dirt or debris in the recessed area around the pintle

A build-up of burnt engine oil on the shaft of the pintle which may cause the pintle to

IMPORTANT: Do not energize the camshaft position (CMP) magnet using a

12-volt power supply.

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

stick and not move freely within the proper range of travel

2. Holding the CMP magnet with the pintle facing upward, measure the pintle retracted

position (a). Record the dimension.

Fig. 80: Measuring The Pintle Extended Position
Courtesy of GENERAL MOTORS CORP.

3. Holding the CMP magnet with the pintle facing downward, measure the pintle extended

position (a). Record the dimension.

4. Subtract the retracted dimension from the extended dimension to determine pintle travel. A

properly moving pintle will travel 3.0-5.5 mm (0.12-0.22 in).

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