Electric Cooling Fan Failure An electric cooling fan which isn't coming on can cause your engine to overheat. When your Nissan Xterra XE isn't going fast. Why does my Xterra's engine overheat? There are two main causes for engine overheat: ⚠️ The coolant does not flow through the system like it should. These. A leaking Engine Coolant Thermostat Housing can lead to other vehicle damage. Without a properly functioning cooling system, your vehicle can overheat.