* Water pump leak: The water pump is a common culprit. If the seal on the water pump is failing, coolant will leak from the weep hole (a small hole designed to indicate a failing seal) or from a crack in the pump itself. This is often located near the bottom of the engine.
* Cracked engine block or head gasket: A much more serious problem, a crack in the engine block or a blown head gasket can allow coolant to leak into the engine oil (resulting in milky oil) or directly to the outside. This usually isn't limited to just one spot.
* Radiator hose connection leak: While you said *beneath* the radiator, a leak from a lower radiator hose or its connection to the engine could drip down to that location. Inspect the clamps and hose itself carefully.
* Thermostat housing leak: A crack or a bad seal in the thermostat housing can cause a leak, and the coolant might drip down.
* Other hoses and connections: There are several other hoses and connections in the cooling system that could be leaking, and their location could make the leak appear to originate from the bottom of the engine.
* Transmission cooler leak (if integrated with radiator): If your transmission cooler is integrated into your radiator and there's a leak within that cooler section, the transmission fluid *might* appear as a coolant leak if mixed. This is less likely, as it would typically show transmission fluid characteristics.
To pinpoint the source:
1. Clean the area thoroughly: Wash away any existing coolant to get a clean look at where the leak is originating.
2. Run the engine: Let the engine run (safely, with proper precautions) and carefully observe where the coolant is leaking from. Have someone monitor the engine while you look from beneath the vehicle for a better view.
3. Pressure test the cooling system: A pressure test applied by a mechanic can help isolate a leak by pressurizing the system and making it easier to see where the coolant escapes.
Do not ignore a coolant leak. Driving with a low coolant level can cause overheating, leading to severe engine damage. It's crucial to diagnose and repair the leak as soon as possible. A mechanic will be able to properly diagnose the problem.
