Ford Triton spark thread repair

June 16, 2011
"I’ve got to let you know up front that a tune-up on your truck may cost up to $1,500.”

"I’ve got to let you know up front that a tune-up on your truck may cost up to $1,500.”

How do you think your customer will take it when you tell him that?

As you may already know, if the spark plugs break off in the cylinder heads of Ford’s Triton (three-valve) engines you may have to pull the cylinder heads to retrieve the broken parts.

Ford knows about the problem and issued a technical service bulletin about it. The TSB states: “Some 2004-2008 F-150, 2006-2008 Mark LT, 2005-2008 F-Super Duty, Expedition, and Navigator, with 5.4L 3-V engine; 2005-2008 Mustang, 2006-2008 Explorer, Mountaineer, and 2007-2008 Explorer Sport Trac with 4.6L 3-V engine; 2005-2008 F-Super Duty, 2006-2008 and F-Stripped Chassis, with 6.8L 3-V engine may experience difficulty with spark plug removal. This may cause damage to the spark plug and leave part of the spark plug in the cylinder head. Affected engine build dates are as follows: 5.4L 3-V and 6.8L 3-V before 10/9/07, 4.6L 3-V before 11/30/07.”

The threads on these extended reach spark plugs do not extend to the end of the spark plug holes in the heads. There is a shell that extends about an inch down the hole into the combustion chamber. A loop at the bottom of the shell forms the ground electrode.

During engine operation, carbon builds up on the shell between it and the cylinder head. As the carbon cokes and hardens, this acts as a “locking agent,” preventing the shell from coming out of the cylinder head during spark plug removal.

Sometimes the shell stays behind while the rest of the spark plug breaks away. Sometimes, it’s worse and the porcelain insulator remains with the shell.

If the spark plugs cannot be fully removed, the solution can involve removal of the cylinder heads, with the spark plug pieces removed at the machine shop. That’s when it gets expensive... real expensive.


According to Ford, it is important that the spark plugs only be removed from an engine that is at room temperature. That means you must bring it into the shop well in advance of starting work or push it into the service bay. You don’t want to try removing the plugs on a hot engine. That is almost a guarantee of failure.

According to the Ford TSB, after removing the coil-on-plug you must blow any dirt from the spark plug wells. Next, you must loosen the plugs no more than 1/8 to 1/4 turn. Then you must fill the spark plug well with carb cleaner up to the hex on the spark plugs. Then you should go to lunch for at least a half-hour.

When you get back to the shop, remove the plugs by hand. You may have to work the spark plug back and forth repeatedly. One of four things can happen:

1. The spark plug comes out (it can happen, really).

2. The ground electrode and shell may remain in the head.

3. The porcelain insulator may be left inside the ground electrode shell.

4. The insulator may break leaving broken porcelain in the ground electrode shell.

A special tool is available from Rotunda (tool #303-1203), but it can only remove the ground electrode shell. If the entire insulator has stayed behind, you may be able to wiggle it out of the shell using needle nose pliers. But if the insulator has broken, you will need Rotunda tool number 303-1398 with which you glue (Loctite) a pin into the center of the insulator (where the positive electrode used to be). Next, go to dinner while this setup cures for an hour. Then, use the tool to pull the insulator from the shell followed by the other tool to remove the shell. Got that?

Fortunately, the tool aftermarket has come to the rescue. Lisle, Snap-on, Mac and others have issued improved tools to remove these problem-child broken spark plugs. They reportedly work better than the Rotunda tools.

[PAGEBREAK] sells both the Rotunda and the Lisle (model LIS 65600) service tools, and the Lisle significantly outsells the Rotunda, according to Dennis Bandy, an ASE-certified master auto technician and tool salesman.

Let’s take a look at how it works.

Since the porcelain insulator usually breaks, it is difficult to extract in order to gain access to the electrode/shell section.

One of the tools in the Lisle kit pushes the broken piece of the insulator into the shell, jamming it in place.

Since the shell and ground electrode is one piece and tapers to a shape resembling a stirrup at the bottom of the shell, the insulator can’t drop into the cylinder.

Once the insulator is pushed down, there is access to the upper portion of the shell into which reverse threads are created using another tool in the kit. The puller tool can then remove the ground electrode/shell piece.

Just be sure to put a thin coat of high-temp, nickel anti-seize on the shell of the new spark plugs to prevent the carbon buildup from repeating the problem. Another problem solver: spark plugs with a one-piece shell such as found on Champion replacement plugs.

With a little luck and the right tools, you may be able to save some time and save your customer some money-maybe even a headache.

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