Pinpoint Test G: Noisy In Forward Gears

WARNING: This page is about a different variant/trim than selected.

NOTE: While verifying the condition, determine whether the noise is gear rollover noise, release bearing rub or some other transmission-related noise. Gear rollover noise, inherent in manual transmissions, is caused by the constant mesh of gears turning at the engine idle speed while the clutch is engaged and the transmission is in NEUTRAL. Release bearing rub is sometimes mistaken for mainshaft bearing noise. Gear rollover noise will disappear when the clutch is disengaged or when the transmission is engaged in gear. Release bearing rub will disappear when the clutch is engaged. In the event that a bearing is damaged, the noise is more pronounced while engaged in gear under load or coast than in NEUTRAL.

Normal Operation and Fault Conditions
- Lubricant
  - Check the transmission fluid level and condition. Refer to the fluid level and condition check in this procedure.
  - Add fluid or drain and fill with specified lubricant. REFER to: Transmission Draining and Filling
- Components grounding out on the transmission
  - Check for any components, screws, or bolts grounding out on the transmission. Repair or install new components as necessary.
- Component housing bolts
  - Check the torque on the transmission case half bolts and the transmission-to-engine block bolts. Tighten or install new bolts as necessary.
- Axle howl or whine
  - The MT88 transmission may be suspect of a gear whine noise, which seems to be emanating from the front or rear of the vehicle at or in excess of 80 km/h (50 mph) at full operating temperature. Drive the vehicle at customer complaint speeds in 4th gear (this is the direct gear) to eliminate manual transmission as noise source, reach full operating temperature and confirm if noise is not present, proceed with gear noise analysis.
  - If noise is still present, REFER to: Front Drive Axle REFER to: Rear Drive Axle and Differential
- Bearings or gears
  - Inspect all bearings, gears, and gear teeth in the transmission for wear or damage. Install new components as necessary.
Possible Sources
- Lubricant
- Components grounding out on transmission case
- Component housing bolts
- Bearings or gears
- Axle howl or whine
Diagnostic steps are not provided for this symptom or DTC. REFER to: Diagnostic Methods