1. Low transmission fluid level: Check the transmission fluid level. If it's low, add the recommended type of transmission fluid.
2. Worn transmission bearings: The bearings in the transmission can wear out over time, causing a noise in certain gears.
3. Damaged gear teeth: If the gear teeth in the transmission are damaged, it can also cause a noise.
4. Damaged synchronizer rings: The synchronizer rings in the transmission help to smooth out the shifting between gears. If they are damaged, it can cause a noise in certain gears.
5. Failed input shaft bearing: The input shaft bearing is located where the transmission input shaft meets the engine flywheel. If this bearing fails, it can cause a whining noise in 5th gear.
To diagnose the exact cause of the noise, it is recommended to have your vehicle inspected by a qualified mechanic.
