Why is there water under the engine?

[Stone]

There are several reasons for water under the engine: Normal phenomenon: If this occurs when the vehicle's air conditioning is running, it is a normal phenomenon. This happens because during air conditioning operation, moisture in the cabin condenses on the evaporator to form water droplets, which are then discharged outside the vehicle through the drain pan and drain pipe. Exhaust pipe dripping: When gasoline burns completely in the engine, it turns into water vapor. This vapor condenses into water droplets as it passes through the metal exhaust pipe. These droplets form water that flows out of the exhaust pipe as dripping, which is actually a good sign. As mechanics often say, the more water a vehicle discharges in winter, the more completely the fuel is burning, indicating better engine performance.

[JuliaMarie]

Last week, I just found a puddle of water under the engine in my garage. After checking for a long time, I realized it was normal drainage from the air conditioning. When you run the AC for extended periods in summer, the condensate water drips down through a dedicated drain tube to the bottom of the engine bay, usually on the passenger side. However, if the liquid feels slippery or smells sweet and is green in color, it’s likely leaking coolant, which needs immediate attention. Other issues like aging radiator connections or a cracked heater hose can also cause coolant leaks. The most troublesome scenario is a blown head gasket, where coolant mixes with engine oil, and white smoke may even come out of the exhaust pipe. I remember once seeing frozen water marks under the car in winter—turned out the windshield washer fluid reservoir had cracked from freezing.

[DiCharles]

A seasoned driver tells you, identifying engine leaks depends on the location and state of the water stains. AC condensation is clear and odorless, dripping most when the engine is running. If it's a light green, sticky fluid, it's 90% likely to be coolant leakage—focus on checking the radiator connections and water pump seals. If the oil cooler is leaking, water and oil will mix into a milky substance. The weirdest case I've seen was a cracked windshield washer tank—it would leak heavily when filled with washer fluid. Water dripping from the exhaust pipe is actually a good sign, indicating complete fuel combustion. If you're really unsure, lay a piece of cardboard under the car overnight and check the leak's location and color in the morning for the most accurate diagnosis.

[GiselleLee]

Engine compartment water leakage is most likely due to the air conditioning system draining, especially noticeable during summer cooling when water drips from the middle of the chassis. However, coolant leaks are more common, typically green/pink/blue in color and slippery to the touch. I've encountered three leaks: a cracked plastic reservoir, an aging water pump seal, and a heater hose chewed by rodents. In winter, beware of the windshield washer tank possibly freezing and cracking. If the temperature gauge rises abnormally or the engine oil turns milky, immediately shut off the engine to check for cylinder head gasket issues. Ordinary AC condensation water can be ignored, but other cases should be inspected and repaired promptly.