Chevrolet Silverado / GMC Sierra. Service manual — part 1018

Converter seal bushing moved forward and damaged

Converter seal garter spring missing from the seal

Porous casting of the transmission case or the oil pump

Leak at the Vent Pipe or the Fluid Fill Tube

Overfilled system

Water or coolant in the fluid-the fluid will appear milky.

Transmission case porous

Incorrect fluid level indicator

Plugged vent

Drain-back holes plugged

Mispositioned oil pump to case gasket, if equipped

ISS or ISS plug loose

ISS O-Ring cut or damaged

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

Fig. 4: Leak Inspection Points
Courtesy of GENERAL MOTORS CORP.

Callout

Component Name

1

Wiring Harness Pass-Through Connector O-ring Seal

2

Transmission Vent Assembly

3

Converter Housing to Case Joint (Pump to Case Oil Seal)

4

Line Pressure Plug

5

Case Extension to Case Seal

6

Manual Shaft Seal

7

Case Extension Oil Seal Assembly

8

Torque Converter Assembly

9

Pump to Case Oil Seal

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

CASE POROSITY REPAIR

Some external leaks are caused by case porosity in non-pressurized areas. You can usually repair
these leaks with the transmission in the vehicle.

1. Thoroughly clean the area to be repaired with a cleaning solvent. Air dry the area.

2. Using instructions from the manufacturer, mix a sufficient amount of an epoxy to make the

repair.

3. While the transmission case is still hot, apply the epoxy. You can use a clean, dry soldering

acid brush to clean the area and also to apply the epoxy cement. Make certain that the area
to be repaired is fully covered.

4. Allow the epoxy cement to cure for three hours before starting the engine.

5. Repeat the fluid leak diagnosis procedures.

SHIFT SOLENOID LEAK TEST

Special Tools

J 35616 GM Terminal Test Kit

J 44246 Solenoid Testing Kit. See Special Tools.

LEAK TEST PROCEDURE

10

Pump Oil Seal Assembly

11

Internal Transmission Speed Sensor to Case O-ring Seal - Some Models

12

2-4 Servo Cover O-ring Seal

13

Oil Fill Tube Seal

14

Oil Cooler Pipe Connectors

15

Transmission Case

16

Transmission Oil Pan Gasket

CAUTION: Epoxy adhesive may cause skin irritations and eye

damage. Read and follow all information on the container
label as provided by the manufacturer.

IMPORTANT:

This procedure tests On/Off type solenoid valves.

Visually inspect the physical condition of the solenoid

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

1. Remove the shift solenoid valve from the control valve body or the torque converter clutch

(TCC) solenoid valve from the transmission case. Refer to Control and Shift Solenoids
Replacement or Torque Converter Clutch Pulse Width Modulation Solenoid,
Torque Converter Clutch Solenoid, and Wiring Harness.

Fig. 5: Installing Valve Into Bore No. 2 Of J 44246
Courtesy of GENERAL MOTORS CORP.

before testing. Inspect the O-rings before and after the
test to be sure that they are not cut or damaged.

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado