Monsoon Season and Your Vehicle

Sun West Transmissions — Glendale, AZ. Free estimates, honest diagnosis and a 3-year / 40,000-mile warranty on qualifying rebuilds and replacements.

Monsoon Season and Your Vehicle

Every summer, Arizona’s monsoon season brings sudden thunderstorms, flash flooding, high winds, and dust storms across the Phoenix area. Streets in low spots can flood within minutes, and dry washes can fill with fast-moving water. Beyond the obvious safety risks, monsoon conditions can damage your vehicle in ways that are not always visible right away, including the transmission, differentials, and electronics. Here is what West Valley drivers should know.

Safety Comes First

Never drive into flooded roads or running washes. Water depth is hard to judge, the roadbed may be washed out, and moving water can push a vehicle off the road. Arizona has a law commonly called the “Stupid Motorist Law” that can make drivers who go around barricades into flooded areas responsible for rescue costs. Turn around and find another route. When a dust storm hits, the Arizona Department of Transportation advises drivers to pull off the road completely, turn off lights, set the parking brake, and keep their foot off the brake pedal so other drivers do not follow their taillights.

How Water Gets Into a Transmission

Transmissions, transfer cases, and differentials have vents that let air move in and out as they heat and cool. When a hot drivetrain suddenly hits cool water, the air inside contracts and can draw water in through those vents. Water can also enter through damaged seals. Even a short trip through deep water can contaminate fluid.

Water in automatic transmission fluid is serious. It breaks down the fluid, damages the bonding material on clutch plates, causes rust on internal parts, and can harm electrical components on transmissions with internal electronics.

Signs of Water Contamination

• Milky, pinkish, or foamy fluid on the dipstick. See transmission fluid colors explained.
• Slipping or erratic shifting after driving through water.
• Shudder or a change in shift feel.
• Warning lights or electrical problems.
• Milky gear oil in a differential or transfer case.

If you see milky fluid, stop driving and have the vehicle inspected. Continuing to drive can quickly spread damage.

Coolant Contamination From Radiator Failures

Not all milky fluid comes from outside water. Many radiators include an internal transmission cooler, and a failure inside the radiator can let coolant mix with transmission fluid. Summer heat and storm-season temperature swings stress cooling systems, so this is worth checking if you notice milky fluid. See radiator replacement.

Dust Storm Effects

Haboobs can coat a vehicle and pack dirt into the radiator and cooler fins, reducing airflow and raising operating temperatures. Dust can also clog cabin and engine air filters. After a heavy storm, gently rinse the radiator and cooler and check your filters. See how Arizona heat affects your transmission.

High Water Through Neighborhoods

Even shallow standing water at intersections can be a problem if it is deeper than it looks. Driving through it quickly can push water into the engine intake, and hitting hidden debris can damage cooler lines or the transmission pan. If you must drive through shallow water, go slowly and steadily.

What to Do After Driving Through Water

1. Check the transmission fluid if your vehicle has a dipstick. See how to check transmission fluid.
2. Have differentials and transfer case fluids checked on trucks and 4x4s. See differential repair and transfer case repair.
3. Watch for changes in shifting, noises, or warning lights.
4. Have brakes checked, since wet brakes and debris can affect performance.
5. If the vehicle was submerged, do not try to start it; have it towed for inspection.

Preparing for Monsoon Season

• Check wiper blades and tire tread for wet roads.
• Have the cooling system inspected before peak heat.
• Make sure fluids are fresh, so you have a clean baseline to compare against.
• Know alternate routes that avoid low-lying roads and washes.

What We Can Do

If water may have reached your transmission, early action matters. Depending on what we find, a fluid flush and replacement may be enough, or internal damage may require more extensive repair. Cost depends on the vehicle and findings. Sun West Transmissions is at 6116 West Northern Ave in Glendale; call (623) 473-9800 for a free estimate. Learn about our transmission service.

Monsoon Season FAQ

How deep does water need to be to damage a transmission?

It depends on the vehicle and vent location. Water does not need to cover the transmission to cause trouble; splashing a hot drivetrain can draw water in through vents.

Can a transmission be saved after water contamination?

Sometimes. If caught early, fluid replacement may be enough. If it has been driven with contaminated fluid, internal repair may be needed.

Should I check my differentials after a storm?

Yes, especially on trucks and 4x4s that drove through water. Milky gear oil needs to be replaced promptly.