Many noises believed to be coming from the transmission
may be originating from other sources such as tires, road surfaces, wheel
bearings, the engine or the exhaust system. These noises may vary according
to vehicle size, type, and amount of body insulation used. A thorough
and careful check should be made to determine the source of the noise
before disassembling the transmission. The transmission gears, like any
other mechanical device, are not absolutely quiet and will exhibit some
normal operating noise. The following is a suggested approach to verify
the suspected transmission noises.
- Select a smooth, level asphalt road to reduce tire noise.
- Drive the vehicle until the coolant has reached normal operating
temperature.
- Record the speed and the gear range at which noise, if any, occurs.
- Check for noises with the engine running and the vehicle stopped.
- Determine in which of the following drive conditions the noise
is occurring:
• | Drive-light acceleration or heavy pull. |
• | Float-maintaining constant vehicle speed at light throttle with
the transmission in gear. |
• | Coast-partially or fully closed throttle with the transmission
in gear. |
- After road testing the vehicle, refer to: