GM Service Manual Online
For 1990-2009 cars only

Many noises that are believed to be caused by the transaxle may be caused by the following sources:

    • The tires
    • The road surfaces
    • The wheel bearings
    • The engine
    • The exhaust system

The noises caused by the above sources vary according to the following conditions:

    • Vehicle size
    • Vehicle type
    • The amount of body insulation used

Thoroughly inspect the vehicle in order to determine the source of the noise before disassembling the transaxle. The transaxle gears are not absolutely quiet and exhibit some normal operating noise. Use the following inspection procedure in order to verify suspected transaxle noises:

  1. Select a smooth, level asphalt road in order to reduce tire noise.
  2. Drive the vehicle until engine coolant has reached normal operating temperature.
  3. If noise occurs, record the speed and the gear range at which the noise occurs.
  4. Inspect for noises when the engine is running and the vehicle is stopped.
  5. Determine in which of the following drive conditions the noise occurs:
  6. • Drive -- a light acceleration or a heavy pull
    • Float -- maintaining a constant vehicle speed at a light throttle when the transaxle is in gear.
    • Coast -- a partially or fully closed throttle when the transaxle is in gear.
    • All of the above drive conditions
  7. After road testing the vehicle, refer to the following procedures for the diagnosis of transaxle noise under various conditions:
  8. •  Noise Changes on a Different Type of Road
    •  Noise Tone Lowers as Car Speed is Lowered
    •  Noise Most Pronounced on Turns
    •  Noise is the Same in Drive or Coast
    •  Knock at Low Speeds
    •  Transmission Clunk on Acceleration or Deceleration
    •  Noisy in Neutral with Engine Running
    •  Noisy in First Gear Only
    •  Noisy in Second Gear Only
    •  Noisy in Third Gear Only
    •  Noisy in Fourth Gear Only
    •  Noisy in Fifth Gear Only
    •  Noisy in Reverse Only
    •  Slips out of Gear
    •  Hard Shifting Effort