What Are the Hazards of Overfilling Transmission Fluid?
1 Answers
Hazards of excessive transmission fluid level: 1. Automatic transmission may leak oil externally: When the transmission fluid level is too high, rotating components come into contact with the oil during operation. Under the high-speed rotation of planetary gear mechanisms or clutches, the oil becomes agitated, leading to expansion and boiling, causing it to leak out through the filler hole and vent valve. 2. Can cause shifting shock: Excessive air entering the fluid can also cause air blockage at the drain holes on the control valve body, resulting in poor drainage and leading to shifting shock. 3. Can result in low working oil pressure: An excessively high transmission fluid level causes rotating components to agitate the oil, leading to the formation of bubbles. When this aerated oil enters the oil pump, the pump cannot establish the required oil pressure. Overfilling the transmission fluid beyond the maximum limit makes it easier for the oil to foam during gear rotation. 4. Reduces the cooling function and transmission efficiency of the transmission: The main functions of transmission fluid are lubrication and cooling. The fluid dissipates heat through the transmission housing and the transmission cooler. If too much oil is added, gear rotation encounters greater resistance, reducing the transmission's cooling function and efficiency. This requires the engine to consume more fuel, decreasing the vehicle's fuel economy. Additionally, this energy loss is converted into heat within the transmission, causing its temperature to rise continuously. Ultimately, this leads to premature wear of bearings and burning of friction plates inside the transmission, both of which are expensive to replace or repair. In summary, the fluid level should neither be too high nor too low.
