Mercury Problems

RepairPal has identified the most common problems with the Mercury as reported by actual vehicle owners. We'll tell you what the problem is and what it'll take to fix it.

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140
Known Problems

The composite (plastic) intake manifold may crack near the thermostat housing and cause a coolant leak. Ford released an updated manifold that was reinforced to prevent a recurrence. No recall was issued for this problem but Ford did extend the warranty to seven years on some models from the date of purchase.

If you experience difficulty starting the engine when cold, stalling at idle, or hesitations during acceleration, it may be the idle air bypass valve. This valve helps the vehicle idle steady when the accelerator pedal is not pressed.

Our technicians tell us the spark plugs in this engine can be very difficult to remove. Ford has issued a service bulletin (08-7-6) to address this issue, which includes a recommended procedure on how to remove the plugs. Failure to follow the recommended procedure can result in the one or more spark plugs breaking off in the cylinder head.

The recommend procedure is as follows. Using this procedure will greatly reduce the chance of breaking a spark plug.

1. Break the spark plugs loose when the engine is warm.
2. Turn each plug 1/8 to 1/4 turn and soak the treads with 1/2 to 3/4 teaspoon of Motorcraft Carburetor Tune-Up Cleaner or a quality penetrating oil. Do not try to remove the plugs at this time.
3. Let the threads soak for at least 15 minutes.
4. After the soak period, tighten and loosen each spark plug, working it back and forth until the turning effort is reduced. Then, you can remove the spark plug.

There are special tools available to remove the broken spark plugs and repair shops will often charge additional labor time, over and above the quoted spark plug replacement cost, for the removal of each broken spark plug.

The 2008-2009 Mercury Sable equipped with automatic temperature control may have a problem with frequent fan speed changes when using the heater or air conditioner. Normally, the fan speed changes only to maintain a selected temperature, but when the fan speed changes frequently and needlessly, there is an issue with the fan speed control unit. 

The fan speed control unit, sometimes erroneously called the blower motor resister, regulates the speed for the blower motor in order to maintain the temperature set by the driver. When it fails, the fan will run at random settings, and the climate control will be inaccurate.

Note: this does not affect the temperature of the air that comes from the vents, it affects the amount of air that comes from the vents. 

The repair is simple, and quick. The control unit is located behind the glove box in most models, and removal and installation takes only minutes.

Also note: this only applies to vehicles with single or dual automatic climate control.

The EGR valve position (EVP) sensor can fail on this vehicle. The EVP sensor measures the EGR valve position and transmits the date to the engine control computer. If it fails, drivability and fuel economy can suffer, the Check Engine Light will commonly illuminate.

An alternator pulley, of the incorrect size, installed at the factory can be the cause of drive belt failure and illumination of the battery light. The alternator pulley should be inspected and replaced as necessary if the drive belt brakes. When the new belt installed, it must be adjusted to the proper tension.

Bad spark plugs or an ignition coil can cause ignition misfire, which will illuminate the Check Engine Light.

The throttle position sensor (TPS) may fail. Common symptoms of a defective TPS can be rough idle, hard starting, hesitation on acceleration, poor fuel economy, and stalling.

A spring in the seat belt buckle may wear or fail, causing the airbag light on the instrument panel to illuminate. Failed buckles will require replacement.

The engine oil pan gasket can develop a leak. Leaking oil may accumulate on the exhaust system resulting in a burning smell. Replacing the gasket should correct this leak.

Looseness in the steering shaft and steering shaft coupling U-joint can cause a knocking / popping noise from the steering column when turning. The steering shaft and coupling U-joint will need to be replaced.

The composite (plastic) intake manifold may crack near the thermostat housing and cause a coolant leak. Ford released an updated manifold that was reinforced to prevent a recurrence. No recall was issued for this problem but Ford did extend the warranty to seven years on some models from the date of purchase.

If you experience difficulty starting the engine when cold, stalling at idle, or hesitations during acceleration, it may be the idle air bypass valve. This valve helps the vehicle idle steady when the accelerator pedal is not pressed.