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Mercury Cougar Problems

RepairPal has identified the most common problems with the Mercury Cougar 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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14
Known Problems

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.

The 4.6L V8 engine used in the Mercury Cougar from 1994-1997 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. 

The Check Engine Light can illuminate with codes due to the lack of EGR (exhaust gas recirculation) flow caused. This is commonly a result of a clogged passage in the intake manifold. To correct this problem, the EGR valve has to be removed and the passage cleaned thoroughly. Partial restriction of this passage can cause smog test failures for the NOx emissions without causing a drivability symptom.

The Check Engine Light can illuminate with codes due to the lack of EGR (exhaust gas recirculation) flow caused by the intake manifold passage plugging up with carbon and oil. The EGR valve has to be removed and the passage cleaned thoroughly. Partial restriction of this passage can cause Smog test failures for the NOx emissions without causing a drivability symptom.

The battery light may illuminate on the instrument panel because the alternator wire harness connector is damaged. A new connector kit is available and should be installed to correct this concern.

The Mercury Cougar 4.6L V8 with a 100% plastic intake manifold is known for engine overheating, even with normal use, and a coolant leak from the front of the manifold. This will often trigger the check engine light and low engine coolant warning light.

The engine coolant leak is from a factory defect, which causes cracking on the front coolant passage of the intake manifold. In a very short time, this leak will lead to engine overheating issues, especially while the vehicle is idling.   

Between 1999 and 2001, Ford released an updated version of this engine, known as the 'PI' version with a metal coolant passage on the front of the intake manifold, to prevent future issues.

There is no factory authorized repair for the intake manifold, and replacement is required to correct the engine coolant leak and overheating issues.

 

White smoke coming from the exhaust could indicate that a head gasket has blown or there is a cracked cylinder head. Our technicians tell us that removal and inspection of the cylinder heads will be required to confirm a crack is present.

For the 2.3L 4 Cylinder and 5.0L V8 engine, the electrical ignition switch poses a fire hazard. An updated switch is available.

While steering, if you hear a clunk or a rattle, or if you experience premature tire wear, this could indicate the inner tie rod ends are loose or worn and will require replacement.

The intake and valve cover gaskets may leak oil.

If the vehicle hesitates or idles roughly after being parked for twenty to thirty minutes, with the engine still warmed to normal operating temperature, you may need to reprogram the PCM (powertrain control module) with new calibration.



Engine misfire could be caused by worn or broken motor mounts that raise the motor on one side while the vehicle is accelerating. The stress on the engine control wiring harness can cause breaks in the injector or sensor wires, which then causes driveability concerns such as poor fuel economy and engine misfires.

Engine misfire could be caused by worn or broken motor mounts that raise the motor on one side while the vehicle is accelerating. The stress on the engine control wiring harness can cause breaks in the injector or sensor wires, which then causes drivability concerns such as poor fuel economy and engine misfires.