Chevrolet Silverado / GMC Sierra. Service manual — part 2141

Fig. 97: Inspecting For Excessive Valve Stem To Guide Clearance
Courtesy of GENERAL MOTORS CORP.

2. A valve stem (1) and guide (2), with excessive clearance, must be replaced or the cylinder

head replaced. Refer to Engine Mechanical Specifications (RPO LY5 VIN J) or Engine
Mechanical Specifications (RPO LC9 VIN 3) or Engine Mechanical Specifications

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

(RPO LY2 VIN C) or Engine Mechanical Specifications (RPO LH6 VIN M) or
Engine Mechanical Specifications (RPO LMG VIN 0) or Engine Mechanical
Specifications (RPO LY6 VIN K) or Engine Mechanical Specifications (RPO L76
VIN Y) or Engine Mechanical Specifications (RPO L92 VIN 8) .

Fig. 98: Identifying Inspection Points For Valves Damage
Courtesy of GENERAL MOTORS CORP.

3. Inspect the valve stems for excessive scoring, wear, or warpage.

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

A valve stem that has excessive scoring (3 or 4) or wear (4 or 6) must be replaced.

If a valve guide is worn or has excessive stem-to-guide clearance, the cylinder head
should be replaced.

4. Measure the valve stem diameter. A valve stem with a diameter less than 7.95 mm (0.313 in)

must be replaced.

If the valve stem diameter is within specifications, and the stem-to-guide clearance is
excessive, the cylinder head must be replaced.

Valve and Seat Grinding

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. 99: Identifying Inspection Points For Valves Damage
Courtesy of GENERAL MOTORS CORP.

IMPORTANT:

Reconditioning the valve seats is very important. The
seating of the valves must be perfect for the engine to
deliver optimum power and performance. Several
different types of equipment are available for grinding
valve seats.

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