Chevrolet Silverado / GMC Sierra. Service manual — part 411

Fig. 46: View Of Drive Belt Tensioner
Courtesy of GENERAL MOTORS CORP.

1. Remove the drive belt. Refer to Drive Belt Replacement .

2. Position a 3/8-inch drive breaker bar into the drive belt tensioner opening and rotate the

tensioner counterclockwise.

3. Move the drive belt tensioner through its full travel.

NOTE:

Allowing the drive belt tensioner to snap into the free position
may result in damage to the tensioner.

IMPORTANT: When the engine is operating the drive belt tensioner arm

will move. Do not replace the drive belt tensioner because of
movement in the drive belt tensioner arm.

2008 Chevrolet Silverado 1500

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

The movement should feel smooth

There should be no binding

The tensioner should return freely

4. If any binding is observed, replace the drive belt tensioner. Refer to Drive Belt Tensioner

Replacement .

5. Install the drive belt. Refer to Drive Belt Replacement .

DESCRIPTION AND OPERATION

DRIVE BELT SYSTEM DESCRIPTION

The drive belt system consists of the following components:

The drive belt

The drive belt tensioner

The drive belt idler pulley

The crankshaft balancer pulley

The accessory drive component mounting brackets

The accessory drive components

The power steering pump, if belt driven

The generator

The A/C compressor, if equipped

The engine cooling fan, if belt driven

The water pump, if belt driven

The vacuum pump, if equipped

The air compressor, if equipped

The drive belt system may use 1 belt or 2 belts. The drive belt is thin so that it can bend
backwards and has several ribs to match the grooves in the pulleys. The drive belts are made of
different types of rubbers, chloroprene or EPDM, and have different layers or plys containing
either fiber cloth or cords for reinforcement.

Both sides of the drive belt may be used to drive the different accessory drive components. When
the back side of the drive belt is used to drive a pulley, the pulley is smooth.

The drive belt is pulled by the crankshaft balancer pulley across the accessory drive component
pulleys. The spring loaded drive belt tensioner keeps constant tension on the drive belt to prevent

2008 Chevrolet Silverado 1500

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

the drive belt from slipping. The drive belt tensioner arm will move when loads are applied to the
drive belt by the accessory drive components and the crankshaft.

The drive belt system may have an idler pulley, which is used to add wrap to the adjacent pulleys.
Some systems use an idler pulley in place of an accessory drive component when the vehicle is
not equipped with the accessory.

ENGINE COMPONENT DESCRIPTION

Engine Block

2008 Chevrolet Silverado 1500

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

Fig. 47: Identifying 6.6L Cylinder Locations
Courtesy of GENERAL MOTORS CORP.

The engine block utilizes a deep skirt design for increased rigidity. The cylinders are positioned
in a 90 degree "V" orientation with the number one cylinder being the right front. The block is
induction hardened for increased durability. The crankshaft bearing caps are cross-bolted to
enhance structural rigidity.

Upper Oil Pan

2008 Chevrolet Silverado 1500

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