Unfortunately, Ford had one of two issues with sparkplugs in many of their V8s from years 1999-2009. Please look below to determine if your Ford could have issues with sparkplugs.

SPARK PLUG BLOWOUT ISSUE (Threads too short)

ENGINE FAMILY

4.6L, 5.4L, and 6.8L Triton V8/V10 – 2-valve versions (2V) These engines had only 4 thread engagement in the aluminum cylinder head. Over time, plugs could eject violently.

YEARS

Roughly 1996–2003, with some models into 2004 before the updated head design.

COMMON VEHICLES

These were extremely widespread. The affected engines were used in:

F-Series Trucks

F-150: 1997–2003
F-250 / F-350 Super Duty: 1999–2003 (gas engines)
F-450 / F-550: 1999–2003 (gas models)

SUVs

Ford Expedition: 1997–2003
Lincoln Navigator: 1998–2003
Ford E-Series vans (E150–E350): 1997–2003
Ford Excursion (gas): 2000–2003

Other Platforms

6.8L V10 in:

F-Series Super Duty: 1999–2003
E-Series: 1997–2003
Motorhome chassis using Triton V10 (common blowouts)

Symptom:

Plugs eject suddenly, usually under load or after improper torque.

References

Spark Replacement

Thread Repair

Thread Repair

SPARK PLUG BREAKAGE ISSUE (Threads too long, 2-Piece plugs”)

ENGINE FAMILY

5.4L and 4.6L Triton V8 – 3-valve versions (3V) Uses a 2-piece extended spark plug design that carbon-locks and breaks during removal.

YEARS

2004–2008 mainly, some 2009 units depending on production date.

VEHICLES AFFECTED

F-Series Trucks

F-150: 2004–2008
F-250 / F-350 (gas 5.4L): 2005–2007
F-450 / F-550 (gas): 2005–2007

SUVs

Ford Expedition: 2005–2008
Lincoln Navigator: 2005–2008

Vans

Ford E-Series (E150–E350):

5.4L 3V: 2005–2008
Later E-Series also had 3V engines but used improved plug design post-2009.

Other

Ford Explorer 4.6L 3V: 2006–2010 (less common but same plug design)
Mercury Mountaineer 4.6L 3V: 2006–2010

Symptom:

Plug separates — shell stays in head while electrode/nose breaks off. Requires special extraction tools.

References

Spark Replacement

Plug Removal

Summary Table

Issue Type	Engine	Years	Vehicles Commonly Affected
Blowout (short threads)	4.6L / 5.4L / 6.8L Triton 2V	1996–2003 (some 2004)	F-150, Super Duty, Expedition, Navigator, E-Series, Excursion, V10 motorhomes
Breakage during removal (long 2-piece plugs)	4.6L / 5.4L Triton 3V	2004–2008 (some into 2009)	F-150, Super Duty gas, Expedition, Navigator, E-Series, Explorer 4.6, Mountaineer