GM Service Manual Online
For 1990-2009 cars only

RPM Sensitive Whine

Checks

Action

DEFINITION: In All Ranges: a whine which may be sensitive to RPM load, or which ceases when the TCC engages

Torque Converter (55)

Verify that the noise is internal to the torque converter by placing your left foot on the brake with the gear or selector in Drive. Momentarily stall the engine. Torque Converter noise increases under load.

High Pitch Whine

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Action

DEFINITION: A high pitch whine which will intensify with engine RPM or which is sensitive to the oil pressure

Oil Pump System

Verify that the noise is internal to the oil pump during a preliminary oil pressure check. An increase in line pressure will vary an oil pump noise.

Popping

Checks

Action

DEFINITION: A Popping noise, similar to popcorn popping

Oil Pump System

    • Inspect for pump cavitation, indicated by bubbles in fluid
    • Inspect the transmission fluid filter for a leaky seam
    • Inspect the transmission fluid filter seal for improper positioning or for a cut seal

Buzz or High Frequency Rattle

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Action

DEFINITION: A Buzz or High Frequency Rattle

    • Trace Cooler Pipes
    • Inspect for binding or contact at the radiator, other than at the cooler pipe connectors.

Verify a pressure buzz by watching for a needle vibration of the pressure gage. A road test may be necessary. Refer to Road Test .

Whine or Growl

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Action

DEFINITION: A Whine or Growl that increases and fades with vehicle speed and is most noticeable under light acceleration

Drive Link Assembly System

Verify that the noise comes from the sprockets or the from the drive ink assembly, chain, by placing your left foot on the brake and by moving the gear selector from Park or Reverse. If the noise stops, check the following items.

Drive Chain (36)

Stretched

Drive Sprocket (37) and Driven Sprocket (91)

    • Broken or sheared teeth
    • Nicked or scored bearing surfaces
    • The bearing race or roller bearing surfaces on the gear support inner bearing are rough or pitted
    • A damaged bearing

Drive Sprocket Support (43) and Driven Sprocket Support (95)

The bearing outer race support is rough or nicked

Final Drive Hum

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Action

DEFINITION: A Final Drive Noise or Hum is most noticeable under light throttle acceleration or turns

    • Final Drive Gear Set (116)
    • Final Drive Internal Gear (118)
    • Worn planet pinions
    • Worn washers
    • Worn or damaged teeth
    • Differential Carrier (116)
    • Differential Side Gears (709)
    • Worn or pitted gears
    • A damaged thrust washer

Forward Ranges

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Action

DEFINITION: Noise in 1st, 2nd, 3rd, or 4th

    • Final Drive Sun Gear (115)
    • Final Drive Pinions (707)

Worn or damaged gears

Random Ranges

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Action

DEFINITION: Noise only in certain gear ranges

Refer to Range Reference . Determine the power flow and the applicable components that may be causing this noise.