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2010 Mercury Mountaineer Problems

RepairPal has identified the most common problems with the 2010 Mercury Mountaineer based on complaints from actual vehicle owners. We'll tell you what the problem is and what it'll take to fix it.

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Known Problems

The 4.6L V8 engine used in the Mercury Mountaineer from 2002-2010 is known for displaying the normal symptoms of a coolant leak, including overheating, especially when the vehicle is idling, the strong smell of coolant from the engine, and illumination of the low engine coolant warning light

This leak is difficult to locate as it is buried underneath the intake manifold, and only begins to leak coolant onto the ground in advanced stages of disrepair. This leak springs from the heater tube, which allows coolant to flow between the water pump and HVAC heater core

When the connection for this tube begins to leak, the coolant burns on the hot engine, and produces a sweet smell that is unmistakably engine coolant. 

The remedy can be complicated, and will necessitate removal of the intake manifold, heater tube, and possibly the water pump. After removal of these items, the connector may be replaced, or a set of o-rings, depending on the year of the vehicle. 

A failed heater blend door or actuator can cause the temperature control for the HVAC system to stop working. A clicking sound from the dash area would commonly indicate an actuator fault. If the heater gets stuck on the hottest setting, the heater blend door may be broken requiring replacement of the heater box to repair the issue.