Spark Plugs May Be Difficult to Remove on Mercury Mountaineer

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.

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Average mileage: 78,333 (61,000–109,000)
Engine affected: 4.6L V8
3 model years affected: 2006, 2007, 2008
7 people reported this problem
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problem details
2006 Mercury Mountaineer - 4.6L V8 65,000 mi,
My husband was changing the spark plug and it broke off. He has been trying to get it out for several days with no luck.
First change of the plugs since mile one. Car started stuttering between 40-55 MPH so it was tyme to change the plugs. Followed all advise and instructions but still broke off two. Bought the Lisle tool to remove broken plugs and eventually got the two out and new ones in. Car is running great now but along comes a front wheel squeal. Could be it's tyme to replace the dry excluder seals.