What Causes A Spark Plug To Eject (And How To Fix It)
It doesn't matter what type of vehicle you drive or which type of spark plug you're using. If your car has an internal combustion gasoline engine, it has the potential to eject a spark plug — although some engines are more likely to do so than others. Ford Triton engines, including 4.6-liter, 5.4-liter, and 6.8-liter varieties from 1997-2003, are infamous for ejecting spark plugs. The Triton engine was designed for use in F-Series pickups, E-Series vans, and Expedition SUVs, but some iterations saw limited use in the company's sportier vehicles, like the Mustang Cobra R.
Some factors, like poor cylinder head designs with threaded sections that are too short to accept spark plugs, contribute to spark plug ejection. But the amount of torque applied during spark plug installation can cause ejection in just about any engine. Even if a torque wrench is too mundane to make the list of your favorite automotive specialty tools, it's something you should always have in your tool kit, especially if you're changing spark plugs.
Spark plugs must be torqued to the proper specification to get the best results. Consult a technical manual for the specific spark plug torque spec used in your car. Installing spark plugs without enough torque can cause them to vibrate loose and damage the cylinder head's threads before making their exit. On the other hand, installing them too tightly can damage the threads of the cylinder head and spark plug. Those weakened and damaged threads can also result in spark plug ejection.
Once a spark plug has been ejected, there isn't much hope for the plug itself. Fortunately, the spark plug is the least expensive part of the ordeal. The next automotive part of concern is the ignition coil pack, which is attached to the spark plug in many modern vehicles, including Ford Triton engines. Even if the coil pack appears undamaged, it's not a bad idea to replace your ignition coils when you replace the spark plugs.
That leaves the most intimidating part of the repair, which involves fixing the damaged threads in the cylinder head spark plug hole. One method that's been around for over 80 years is the Heli-Coil system. Heli-Coils are thread-shaped wire coil inserts that screw into oversized threads made by a special Heli-Coil tap. The inside thread of the Heli-Coil is sized to replace the damaged thread.
Another method to repair damaged threads is the Time-Sert. It uses a similar process that requires drilling and tapping the spark plug hole to a larger thread size. However, the Time-Sert insert is solid compared to the wire coil construction of the Heli-Coil.
As for Ford vehicles in particular, one of the best purchases you could make for repairing a Triton engine's ejected spark plug is a repair kit from Cal-Van Tools. You can find such a kit for $212.99 at Summit Racing Equipment. It comes with thread inserts, a reamer, and a tap to replace the damaged cylinder head threads. It also comes with an alignment jig to ensure the new threads are in-line with the old ones.
