Chevrolet Silverado / GMC Sierra. Service manual — part 1017

Missing or loose balance weights

Imbalance caused by heat distortion or fluid contamination

CLUTCH PLATE DIAGNOSIS

COMPOSITION PLATES

Dry the plates and inspect the plates for the following conditions:

Pitting

Flaking

Delamination-splitting or separation of bonded clutch material

Wear

Glazing

Cracking

Charring

Chips or metal particles embedded in the lining

Replace a composition plate which shows any of these conditions.

STEEL PLATES

Wipe the plates dry and check the plates for heat discoloration. If the surfaces are smooth, even if
color smear is indicated, you can reuse the plate. If the plate is discolored with heat spots or if the
surface is scuffed, replace the plate.

CAUSES OF BURNED CLUTCH PLATES

The following conditions can result in a burned clutch plate:

Incorrect usage of clutch or apply plates

Engine coolant or water in the transmission fluid

A cracked clutch piston

Damaged or missing seals

Low line pressure

Valve body conditions

The valve body face is not flat.

Porosity is between channels.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

The valve bushing clips are improperly installed.

The checkballs are misplaced.

The Teflon® seal rings are worn or damaged.

ENGINE COOLANT/WATER IN TRANSMISSION

If antifreeze or water has entered the transmission, perform the following:

1. Disassemble the transmission.

2. Replace all of the rubber type seals (the coolant will attack the seal material which will

cause leakage).

3. Replace the composition-faced clutch plate assemblies and the 2-4 band assembly (the

facing material may separate from the steel center portion).

4. Replace all of the nylon parts (washers).

5. Replace the torque converter.

6. Thoroughly clean and rebuild the transmission, using new gaskets (bonded and non bonded),

and oil filter.

7. Flush the cooler lines after the transmission cooler has been properly repaired or replaced.

FLUID LEAK DIAGNOSIS

GENERAL METHOD

1. Verify that the leak is transmission fluid.

2. Thoroughly clean the suspected leak area.

3. Operate the vehicle for 24 km (15 mi), or until normal operating temperatures are reached.

4. Park the vehicle over clean paper or cardboard.

5. Shut OFF the engine.

6. Look for fluid spots on the paper.

7. Make the necessary repairs.

POWDER METHOD

NOTE:

The antifreeze or water will deteriorate the seals, gaskets and the
glue that bonds the clutch material to the pressure plate. Both
conditions may cause damage to the transmission.

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

1. Thoroughly clean the suspected leak area with solvent.

2. Apply an aerosol type powder, such as foot powder, to the suspected leak area.

3. Operate the vehicle for 24 km (15 mi), or until normal operating temperatures are reached.

4. Shut OFF the engine.

5. Inspect the suspected leak area.

6. Trace the leak path through the powder in order to find the source of the leak.

7. Make the necessary repairs.

DYE AND BLACK LIGHT METHOD

A fluid dye and black light kit is available from various tool manufacturers.

1. Follow the manufacturer's instructions in order to determine the amount of dye to use.

2. Detect the leak with the black light.

3. Make the necessary repairs.

FIND THE CAUSE OF THE LEAK

Pinpoint the leak and trace the leak back to the source. You must determine the cause of the leak
in order to repair the leak properly. For example, if you replace a gasket, but the sealing flange is
bent, the new gasket will not repair the leak. You must also repair the bent flange. Before you
attempt to repair a leak, check for the following conditions, and make repairs as necessary:

Gaskets

Fluid level/pressure is too high

Plugged vent or drain-back holes

Improperly tightened fasteners

Dirty or damaged threads

Warped flanges or sealing surface

Scratches, burrs, or other damage to the sealing surface

Damaged or worn gasket

Cracking or porosity of the component

Improper sealant used, where applicable

Incorrect gasket

Seals

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado

Fluid level/pressure is too high

Plugged vent or drain-back holes

Damaged seal bore

Damaged or worn seal

Improper installation

Cracks in component

Manual or output shaft surface is scratched, nicked, or damaged

Loose or worn bearing causing excess seal wear

Damaged ISS O-Ring

POSSIBLE POINTS OF FLUID LEAKS

Transmission Oil Pan

Incorrectly tightened oil pan bolts

Improperly installed or damaged oil pan gasket

Damaged oil pan or mounting face

Incorrect oil pan gasket

Case Leak

Damaged or missing fill tube seal

Mislocated fill tube bracket

Damaged vehicle speed sensor seal

Damaged manual shaft seal

Loose or damaged oil cooler connector fittings

Worn or damaged propeller shaft oil seal

Loose line pressure pipe plug

Warped

Distorted torque converter housing

Porous casting

Leak at the Torque Converter End

Converter leak in the weld area

Converter seal lip cut. Check the converter hub for damage

2008 Chevrolet Silverado 1500

2008 TRANSMISSION Automatic Transmission - 4L60-E/4L65-E/4L70-E - Cab & Chassis Sierra, Cab & Chassis

Silverado, Sierra & Silverado