What are signs of a bad gearbox?

Common manifestations of transmission failures include gear shifting jolts, abnormal noises, oil leaks, engine stalling when shifting gears, abnormal temperatures, and power transmission failure. Gear shifting jolts are usually caused by solenoid valve blockage or deteriorated transmission oil, presenting as a noticeable jolt when shifting up. Oil leaks lead to reddish-brown oil stains on the ground, possibly caused by aged oil seals or damaged gaskets, which require timely repair to avoid insufficient lubrication. Engine stalling when shifting gears may be related to lock-up solenoid valve malfunctions, and vigilance against the risk of power transmission interruption is necessary. Additionally, if the dashboard displays a transmission overheating warning or the SPT light flashes, it may be due to high-load operation or sensor failure, while the vehicle failing to move after shifting to D/R gear involves mechanical issues such as clutch or brake damage. If the above symptoms occur, It is best to stop driving immediately and contact professional maintenance to prevent the failure from worsening. Maintenance solutions should be selected based on specific problems, such as replacing seals, cleaning valve bodies, or overhauling the transmission, with priority given to regular manufacturers to ensure quality.