Chevrolet Silverado / GMC Sierra. Manual — part 1016

External leaks appear in the hub weld area.

The converter hub is scored or damaged.

The converter pilot is broken, damaged, or fits poorly into the crankshaft.

You discover steel particles after flushing the cooler and the cooler lines.

The pump is damaged, or you discover steel particles in the converter.

The vehicle has TCC shudder and/or no TCC apply. Replace the torque converter only after
all hydraulic and electrical diagnoses have been made. The converter clutch material may be
glazed.

The converter has an imbalance which cannot be corrected. Refer to Flexplate/Torque
Converter Vibration Test.

The converter fluid is contaminated with engine coolant or water.

An internal failure occurs in the stator roller clutch.

You notice excessive end play.

Overheating produces heavy debris in the clutch or converter ballooning.

You discover steel particles or clutch lining material in the fluid filter or on the magnet,
when no internal parts in the unit are worn or damaged. This condition indicates that lining
material came from the converter.

Do not replace the torque converter if you discover any of the following symptoms:

The oil has an odor or the oil is discolored, even though metal or clutch facing particles are
not present.

The threads in one or more of the converter bolt holds are damaged. Correct the condition
with a new thread inset.

Transmission failure did not display evidence of damaged or worn internal parts, steel
particles or clutch plate lining material in the unit and inside the fluid filter.

The vehicle has been exposed to high mileage only. An exception may exist where the lining
of the torque converter clutch dampener plate has seen excess wear by vehicles operated in
heavy and/or constant traffic, such as taxi, delivery, or police use.

FLEXPLATE/TORQUE CONVERTER VIBRATION TEST

ISOLATING VIBRATION

NOTE:

Some engine/transaxle combinations cannot be balanced in this
manner due to restricted access or limited clearances between the
torque converter bolts and the engine. Ensure that the bolts do not

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

To isolate and correct a flywheel or torque converter vibration, separate the torque converter
from the flywheel to determine if vibration is in the engine or transmission.

1. With the engine at idle speed and the transmission in PARK or NEUTRAL, observe the

vibration.

2. Turn the engine OFF.

3. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle .

4. Remove the transmission converter cover bolts and the cover.

5. Mark the relationship of the converter to the flywheel.

6. Remove the bolts attaching the converter to the flywheel.

7. Slide the torque converter away from the flywheel.

8. Rotate the flywheel and torque converter to inspect for defects or missing balance weights.

Refer to Automatic Transmission Flex Plate Cleaning and Inspection .

9. Lower the vehicle.

10. With the engine at idle speed and the transmission in PARK or NEUTRAL, observe the

vibration. Refer to Diagnostic Starting Point - Vibration Diagnosis and Correction .

11. Turn the engine OFF.

INDEXING TORQUE CONVERTER

To determine and correct a torque converter vibration, the following procedure may have to be
performed several times to achieve the best possible torque converter to flywheel balance.

1. Raise and suitably support the vehicle. Refer to Lifting and Jacking the Vehicle .

2. Rotate the torque converter one bolt position.

bottom out in the lug nuts or the torque converter cover which
could dent and cause internal damage.

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

Fig. 3: View Of Torque Converter Hub In Engine Crankshaft
Courtesy of GENERAL MOTORS CORP.

3. Align the torque converter hub (2) in the engine crankshaft (3) and install the torque

converter to flywheel bolts.

4. Lower the vehicle.

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado

5. With the engine at idle speed and the transmission in PARK or NEUTRAL, observe the

vibration. Refer to Noise and Vibration Analysis.

Repeat this procedure until you obtain the best possible balance.

6. Install the transmission converter cover bolts and the cover.

NOISE AND VIBRATION ANALYSIS

A noise or vibration that is noticeable when the vehicle is in motion MAY NOT be the result of
the transmission.

If noise or vibration is noticeable in PARK and NEUTRAL with the engine at idle, but is less
noticeable as RPM increases, the cause may be from poor engine performance.

Vibration may also be caused by a small amount of water inside the converter.

Inspect the tires for the following conditions:

Uneven wear

Imbalance

Mixed sizes

Mixed radial and bias ply

Inspect the suspension components for the following conditions:

Alignment wear or damage

Loose fasteners

Driveline damage or wear

Inspect the engine and transmission mounts for damage and loose bolts.

Inspect the transmission case mounting holes for the following conditions:

Missing bolts, nuts, and studs

Stripped threads

Cracks

Inspect the flywheel for the following conditions:

Missing or loose bolts

Cracks

Imbalance

Inspect the torque converter for the following conditions:

Missing or loose bolts or lugs

2008 Chevrolet Silverado 1500

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

Silverado, Sierra & Silverado