There is a technical service bulletin for the V8 engines regarding a possible problem with the spark plug being ejected from the cylinder head, damaging the threads in the spark plug hole. If the vehicle is under warranty, cylinder head replacement is recommended. If the vehicle is out of warranty, Ford authorized the use of a specific thread insert to repair the head.
Car Problem Reports
Ford Expedition TSB For Possible Ejection of Spark Plug From Cylinder Head
Ford Expedition Problem
Engines Affected: 4.6L V8, 5.4L V8
Average Mileage: 122,350 mi (11,800 mi - 160,000 mi)
Visitor, 2002 Ford Expedition, 5.4L V8, 11,800 mi
Number 5 blew while on vacation - setting in the lounge of a Ford dealership waiting for the verdict. This sucks! Ford should reapir this obvious factory defect free of charge.
Visitor, 2000 Ford Expedition, 5.4L V8, 141,000 mi
Spark plug blew helix coil repair
Visitor, 1998 Ford Expedition, 5.4L V8
bulleted two plugs due to too shallow threading in block
helicoiled both-1000$ a plug
Visitor, 2002 Ford Expedition, 5.4L V8, 120,000 mi
Heard a loud pop, and immediately started missing. Put in insert, new plug, coil, and boot. Hope it makes it another 120,000.
Visitor, 1998 Ford Expedition, 5.4L V8, 140,000 mi
2nd time a plug has blown out
I had a sparkplug blow out of number 3, and had a helix coil installed, then it blew out the helix coil. now, i have to replace the head. needless to say, i dont have th emoney and its parked until i get the money. this should have been recalled a longtime ago.
Visitor, 1997 Ford Expedition, 4.6L V8, 160,000 mi
spark plug blew and stripped the head on the passenger side....replacing with a used head
Visitor, 1999 Ford Expedition, 150,000 mi
it has done it 2 times on 2 different plugs
Visitor, 1998 Ford Expedition, 4.6L V8
spark plug blew out sounds like someone has done this repair to have it happin again 6 months latter
Visitor, 2003 Ford Expedition, 5.4L V8, 98,000 mi
cylinder head blown left side cylinder #7 had repaired when happened first time 6 months ago, now same has happened again to same cylinder-spark plug ejected