Failure mode - Ford Triton gasoline (Super Duty / Excursion / E-Series)

Spark plug breakage on removal (3V heads)

Reliability tier: verified - verify before ordering, see /disclosure/

Symptoms

during a plug change, the plug snaps in half and the lower shell stays stuck in the head
the porcelain separates from the shell; the shell will not unscrew
a shop quotes 'broken plug extraction' as a line item

Root cause

The original 3V plug is two-piece: a nickel-plated shell crimped over the electrode assembly. Carbon build-up in the plug well seats on the shell's blind hole and the shell's thin crimp neck shears when backed out. Ford issued removal instructions (TSB 06152, 'SPARK PLUG REMOVAL INSTRUCTIONS - 5.4 3V') because the breakage rate at plug service was high enough to warrant OEM guidance. The updated one-piece plugs (current PZK-14F, formerly SP-515) end the problem once installed.

Diagnosis

count/verify which plugs are original two-piece before the service (build year + service history)
hot-soak and careful slow removal per the TSB sequence; expect breakage, don't force
if broken: the shell stays in the head - extract with the dedicated tool

Fixes

extract the stuck shell with the dedicated removal tool, then install one-piece updated plugs (extract + update) - the tool is a one-time toolbox buy; extraction is fiddly but no head removal

preventive: careful TSB-sequence removal of original plugs and a one-piece update before they fail (update) - removes the breakage risk for all future services; cost is a routine plug service

Spark Plugs, 3V heads, one-piece updated (Motorcraft SP-546 / Ford PZK-14F)

Prevalence

very-common