Will water entering the car's air intake affect the engine?

[VincentLee]

Yes, it will have an impact. A small amount of water may enter the engine and mix with the engine oil, degrading the oil quality. Oil containing water can increase wear on engine components, potentially leading to increased engine noise and vibration during future driving. Below are precautions for driving through water: 1. Drive in a low gear: Use a low gear (for automatic transmission vehicles, engage the hill-climbing gear) and slowly drive through the water at a steady speed while maintaining control of the steering wheel. Be aware of any potholes or gaps beneath the water on the road. 2. Do not restart the engine after stalling: If the vehicle stalls in a waterlogged area, do not attempt to restart the engine. Engine stalling indicates that water has already entered the cylinders. Restarting the engine can cause severe damage due to the incompressibility of water, potentially bending or breaking the piston connecting rod components and, in severe cases, leading to complete engine failure.

[McJayce]

Once I drove too aggressively through a puddle in the rain, and water got sucked into the intake, causing a hydro-lock. Water in the engine is no joke—when it mixes in the cylinders, the piston can't compress it, and the force bends the connecting rod. The mechanic told me if I had shut off the engine immediately, it might have been salvageable, but I tried restarting it, and the rod punched right through the block. Now I avoid standing water at all costs. Everyone, remember: go slow through water, keep the level below half the tire height, and if the engine stalls, never try to restart it—calling a tow truck is way cheaper than a full engine rebuild. Trust me, spending over 20,000 RMB on a new engine hurts.

[RafaelMarie]

I consulted a friend who works in automotive R&D about this issue. The essence of engine operation is compressing air, and water entering the cylinder simply cannot be compressed. When the crankshaft forces the piston upward against this resistance, it causes mechanical damage. Minor water intrusion may only lead to rusty spark plugs, while severe cases can result in bent connecting rods that render the engine irreparable. While air intakes are designed at high positions, heavy rain or deep water crossings pose risks. I recommend installing a snorkel to raise the air intake height, maintaining safe distances in rainy conditions to avoid bow waves from preceding vehicles, and regularly checking the air filter for moisture. Having seen numerous major repair cases caused by water intrusion during my mechanic work, I can confirm the repair costs often reach half the price of a used car.

[IvanAnn]

Last week, my neighbor Lao Wang's car fell victim to this exact scenario. While driving through a waterlogged area, the engine sputtered a couple of times before stalling. In his rush to get to work, he attempted to restart it, only to end up towing the car to the repair shop where they discovered the connecting rods bent like pretzels. Water entering the cylinders is even more dangerous than sand or gravel—when the pistons move, the water creates immense resistance, causing metal components to deform directly. Right now, Lao Wang's car is still in the shop, and word is they’ll need to replace the entire cylinder block assembly. So here’s a reminder for everyone: before driving in the rainy season, check the weather forecast. Don’t force your way through standing water on the road—if the water level exceeds the centerline of the wheel hubs, it’s risky. If you must wade through, shift to a low gear and maintain a steady speed. After exiting the water, lightly press the brakes to clear any water from the brake pads.

[VanZane]

During the last maintenance, the technician showed me the disassembled parts of a water-flooded engine. It was quite shocking to see the cylinder walls cracked by the connecting rods. The most dreaded scenario with water intake is a secondary startup, as insurance claims won't cover such operational errors. I make it a habit to check the sealing of the intake system before the rainy season, as aged rubber tubes can leak water. For a simple self-check, open the engine compartment when the engine is cold and pour some water into the intake pipe. If it flows into the throttle body, the seals need replacing. Remember 'slow entry, steady exit' when wading through water: reduce speed before entering and maintain steady throttle to prevent high waves. Engine replacements can cost tens of thousands, while these preventive measures cost less than two hundred.

[EmersynRose]

My cousin once saw the worst case at the repair shop: a car with water in the intake forcefully started, causing the piston to crack the cylinder block, spraying oil mixed with coolant everywhere. Water is 800 times denser than air, instantly disrupting the compression ratio when it enters the combustion chamber. It's advised to switch to recirculation mode when using the AC for defogging during rainy days to reduce water intake. If your vehicle is flooded, don't rush to power it on—disconnect the battery and call a tow truck. Some modern cars come with intake humidity sensors, but older models require extra caution. Always park away from low-lying areas, and if modifying the intake system, seek professional shops—haphazard installations can reduce water-wading capability.