Late-model Ford trucks (1997 to 2004 Ford
F-Series, Expeditions and Excursions) are reportedly blowing
out spark plugs. The problem seems to occur most often on
5.4L Triton engines, but may also occur on other V6, V8 and
V10 engines in these vehicles.
The #2, #3 and/or #4 spark plugs tend to work loose and blow
out when the engine has 60,000 to 100,000 miles on it. When
the plug blows out of the cylinder head, it usually damages
the threads in the spark plug hole and also breaks the coil
that sits on top of the plug. In some cases the plugs have
blown out with such force that they have damaged the fuel
The problem appears to be the design of the original
equipment spark plugs and cylinder head. The plugs are only
threaded part way up to where the plug taper seats against
the head. If the plugs are not tightened properly when they
are installed, they may work loose over time and blow out.
Tip: Itís probably a good idea to check the spark plugs on
these engines every 20,000 to 30,000 miles to make sure they
are not coming loose. If a plug feels loose, it should be
tightened to the recommended torque.
If an engine blows a plug, the fix can be expensive. Ford
says a standard Helicoil insert is not adequate, and insists
their dealers replace the entire cylinder head (at a costs
of up to $3,000 for parts and labor). But there are special
tools and inserts for repairing these heads.
Ford TSB 06-5-9 addresses another problem on these engines,
which is getting the original spark plugs out without
breaking the plugs or stripping the threads in the cylinder
head. The recommended removal procedure is to loosen the
plugs on a warm (but not hot) engine about 1/8 to 1/4 turn.
Then soak the base of each plug with penetrating oil. Allow
the oil to wick down the threads for five to 10 minutes
before attempting to remove the plugs. If a plug sticks,
turn it back and forth half a turn, and apply more
penetrating oil. Donít force it, and never use an air tool
to spin it out.
If a plug breaks off, there is a special Rotunda service
tool 303-1203 for extracting the broken plug.