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.Google+
Car Problem Reports
Ford F-150 TSB For Possible Ejection of Spark Plug From Cylinder Head
Ford F-150 Problem
Engines Affected: 4.6L V8, 4.9L 6 Cylinder, 5.4L V8, V8
Average Mileage: 131,619 mi (50,000 mi - 238,890 mi)
Visitor, 2002 Ford F-150, 4.6L V8, 165,000 mi
cylinders #2 and #7 blew out on seperate times. i had to have it tapped and use a steel sleeve. mech. said not enough threads on the head. around $400.00
Visitor, 1999 Ford F-150, 5.4L V8, 118,000 mi
The plugs were replaced with Helio coils, new threaded sleeves in the head. Two have ejected. It is limited to the rear on both sides of the heads. Relatively easy fix, if it happens to one, get all 4 rear ones done to save labor. Should be good to go.
Went to advanced auto parts. Bought a rubber boot/spark plug kit made specifically for this problem. Drove it like that for 2 years until my number 3 did the same thing right before winter. Will fix the same way until I can afford to by after market heads.
Visitor, 2005 Ford F-150, 4.6L V8, 105,000 mi
#7 Cylinder. 15,000 miles after full tune up where all 8 spark plugs were replaced.
Visitor, 2003 Ford F-150, 5.4L V8, 234,000 mi
Started engine and heard a very loud bang and then immediate loud rattle.
Visitor, 2002 Ford F-150, 5.4L V8, 50,000 mi
Driven down the rd and it shot out second from the back passanger side spark plug out suddenly. But it still was able to lip it a couple miles to home were the next morning i repaired it
Visitor, 2003 Ford F-150, 4.6L V8, 89,000 mi
blew spark plug out of cylinder head
Visitor, 1997 Ford F-150, 4.6L V8, 150,000 mi
Finally blew out the #4 plug. Head damaged bad enough where inserts were not an option. Replace the heads with 150k on the lower end??? Nope. Total cost of one blown plug is about 6K.
Visitor, 2000 Ford F-150, 5.4L V8, 90,000 mi
Three of the eight have ejected. Now carry plug, coil and tap every where I go. Now can change out in under 30 minutes.
Visitor, 2002 Ford F-150, 5.4L V8, 170,000 mi
I have had three spark plugs eject over the last two years or so and the number 2 plug just ejected again and my mechanic says I need to replace the head because the aluminum melted around the threaded hole and he can't fix it again with a helicoil.