The Risks of Water Intrusion in Your Car's Automatic Transmission

When driving through a flooded street, it is crucial to be aware of the potential risks involved in allowing water to enter your car's automatic transmission. This blog post aims to explain the conditions under which water can penetrate the transmission, the factors that increase the likelihood of this happening, and how to minimize the risks.

How Easy Can Water Enter an Automatic Transmission?

Water can infiltrate the automatic transmission if the water level is elevated sufficiently to reach the transmission vent or if the transmission cooler lines are submerged. The deeper the flood, the higher the risk of water entering the transmission. The design of the vehicle also plays a crucial role in determining the likelihood of water intrusion.

Factors to Consider

Flood Depth

If the water is above the level of the car's axles or transmission, there is a significant risk of water entering the transmission. Typically, water levels above 12-15 inches can pose a threat to most vehicles. However, the risk increases with deeper water.

Car Type

Vehicles have different designs, and the risk of water entering the transmission varies. For example, trucks and SUVs may have higher ground clearance than sedans, reducing the risk. Some vehicles are also designed with better seals and protections against water intrusion. These features can significantly reduce the likelihood of water entering the transmission.

Transmission Vent

The transmission has a vent to equalize pressure. If water submerges the transmission, it can enter through this vent. Driving through flooded streets can create splashes that may force water into vulnerable areas, including the transmission.

Driving Through Water

Driving through flooded streets can pose a significant risk of water intrusion. Splashes can force water into vulnerable areas of the vehicle, including the transmission. It is critical to avoid driving through flooded areas whenever possible to minimize the risk of water entering the transmission.

Conclusion

To minimize the risk of water entering the transmission, it is best to avoid driving through flooded areas. If you suspect water has entered your transmission, it is crucial to have it inspected immediately to prevent damage. Proper maintenance and understanding the risks are key to ensuring your car's transmission remains in optimal condition.

Personal Experience: A Lesson from the Past

Back in the day, I had to remove my manual gearbox. When I came to drain the oil, it was mostly full of water. Through some detective work, I deduced the source: regular trips through a ford that cooled the gearbox and its oil, drawing in some water through the breather. This water would sink to the bottom, displacing some of the oil. Over time, the gearbox reservoir became more water than oil. This phenomenon would affect an automatic transmission similarly.

Years later, we had a Land Rover where the breathers from the gearbox and differential were attached to pipes venting much higher up the vehicle to avoid the same problem. However, one of these pipes became blocked, leading to the blowing of the rear diff oil seal.

Based on my experience, you would likely get at least some water in the oil or automatic transmission fluid if the wading was a foot or less. An occasional foray into water probably wouldn't cause significant damage, but doing it regularly would be less favorable.

Understanding and mitigating these risks can help you keep your car's automatic transmission operating smoothly.