What Causes Transmission Fluid to Increase?
2 Answers
Transmissions have vent holes that allow moisture from the air to enter, which can then degrade the transmission fluid. This is why transmission fluid needs to be replaced periodically. Below is more information about transmission fluid replacement: 1. Introduction: Transmission fluid is used in automotive transmissions to clean and lubricate the gear system, extend the lifespan of the transmission components, and provides functions such as cleaning, lubrication, rust prevention, and heat dissipation. 2. Types: Depending on the type of vehicle transmission, transmission fluid can be categorized into manual transmission fluid and automatic transmission fluid. 3. Replacement Interval: Generally, it should be replaced every 3 years or approximately 100,000 kilometers.
That day I was helping my friend check his car, and it's indeed rare but not unheard of for the transmission fluid to increase. The most likely cause is coolant leaking into the transmission cooler, as these two systems share components which can lead to cross-contamination. It could also be that the vent hole was clogged with mud, preventing gas from escaping and creating pressure that pushed the oil up. Once, I saw an off-road vehicle whose transmission fluid increased after wading through water, and upon opening it up, water had flooded into the transmission, emulsifying with the oil into a milkshake-like substance. Additionally, not bleeding the air from the lines when adding new fluid or inaccurate fluid level measurement could lead to misjudgment. The worst-case scenario is internal component wear producing metal shavings that cause the oil to foam and expand. If you notice the fluid has increased, you should stop driving immediately, as whitish, emulsified oil can directly damage the clutch plates and planetary gear sets.
