Chevrolet Silverado / GMC Sierra. Service manual — part 610

Fig. 117: View Of Cylinder Head Gasket Markings
Courtesy of GENERAL MOTORS CORP.

2. The markings on the gasket are as follows:

Grade A (1)

Grade B (2)

Grade C (3)

Block over-bored 0.010-0.030 in (0.254-0.762 mm) (4)

Block over-bored 0.010-0.030 in (0.254-0.762 mm) and deck milled 0.008 in (0.203

2008 Chevrolet Silverado 1500

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

mm) (5)

3. The cylinder head gasket thickness is determined by the piston head projection from the

cylinder block deck surface. There are cylinder head gaskets available in three different
thicknesses. Follow the procedure below and refer to Cylinder Head Gasket Selection
Specifications to determine what gasket to use for each bank of cylinders.

4. Be sure the piston and cylinder deck are free of carbon, gasket material, or other objects

that may give you an erroneous measurement.

Fig. 118: Measuring Piston Projection Using J 7872
Courtesy of GENERAL MOTORS CORP.

5. Use J 7872 to measure the piston projection across two different points on each piston.

1. Zero the dial indicator to the cylinder deck surface.

2. Place the dial indicator pointer on the piston top. Be sure the pointer is directly above

the piston pin centerline to prevent inaccurate readings from piston rocking.

2008 Chevrolet Silverado 1500

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

3. Rotate the engine to roll the piston through Top Dead Center while noting the

maximum reading on the dial indicator.

4. Repeat procedure at the second measuring point on the piston.

6. Calculate the average value of piston projection for each cylinder.

7. Obtain the maximum piston projection value for that bank of cylinders.

8. Determine the gasket grade by the maximum piston projection value using the chart.

9. If the difference between the highest measured piston head projection and the lowest

measured piston projection, within one bank of cylinders, exceeds 0.1 mm (0.0039 in), then
the following items need to be checked.

Connecting rod to piston pin clearance

Piston to piston pin clearance

If any of the above clearances are beyond specifications, then refer to the appropriate section for
repair. If all of the above clearances are within the service limits but the piston projection
variation is over 0.1 mm (0.0039 in), then replace the connecting rod and piston assembly.

CYLINDER HEAD INSTALLATION - LEFT SIDE

Tools Required

J 45059 Angle Meter

Installation

2008 Chevrolet Silverado 1500

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

Fig. 119: View Of Cylinder Head Gasket Markings
Courtesy of GENERAL MOTORS CORP.

NOTE:

The left and right cylinder head gaskets are not
interchangeable. Improper placement of the cylinder head
gasket will block coolant and oil passages. Blocked coolant
and oil passages will cause severe engine damage.

IMPORTANT: The stamped letter, R or L, must face up. R is the right bank,

L is the left bank.

2008 Chevrolet Silverado 1500

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