* Water Pump: A failing water pump can leak coolant, and while often visible under the engine, a leak could travel down and collect near the passenger side, especially given the age of your Explorer. The location on the front tire guard might indicate a leak from a lower part of the pump or a hose connected to it.
* Heater Core: This is a strong possibility. The heater core is located inside the passenger compartment, and a leak would drip onto the floor. Because coolant is under pressure, the leak can sometimes find its way through to the outside, particularly down towards the front near the firewall (where the heater core is located). The path of least resistance could lead the coolant towards the front tire guard.
* Hoses: Various hoses connect the radiator, water pump, heater core, and engine block. A cracked or loose hose, particularly one near the passenger side of the engine, is a common cause of leaks. A hose failure higher up could lead coolant to run down.
* Radiator: Although less likely to directly cause a leak in this location, a radiator leak could cause coolant to spill which could then migrate to the passenger side.
* Thermostat Housing: A leak in the thermostat housing, especially if it's near the passenger side, could contribute to the leak you see.
Why the passenger side?
The pathway of the leak is key. Gravity, the engine's tilt, and the vehicle's design influence where the coolant ends up. The passenger side is a common area for leaks to manifest themselves due to the routing of various hoses and components.
What to do:
1. Safety First: Coolant is toxic. Wear gloves and eye protection when inspecting the area.
2. Visual Inspection: Carefully examine the entire engine bay, paying close attention to the water pump, hoses (especially those connected to the heater core and water pump), thermostat housing, and radiator. Look for stains, wet spots, or signs of corrosion. A flashlight will help.
3. Pressure Test: Have a mechanic perform a pressure test on the cooling system. This will pinpoint the location of the leak more accurately.
4. Professional Repair: Unless you have significant automotive experience, it's best to have a qualified mechanic diagnose and repair the leak. Ignoring a coolant leak can lead to serious engine damage.
The location of the leak on the front tire guard and passenger floor strongly points toward a more significant issue than a simple hose clamp. Don't delay getting it checked.
