From Wikipedia:<br><br><h2 style="background-image: none; font-weight: normal; margin: 0px 0px 0.6em; overflow: hidden; padding-top: 0.5em; padding-bottom: 0.17em; border-bottom-width: 1px; border-bottom-style: solid; border-bottom-color: #aaaaaa; font-size: 19.09090805053711px; font-family: sans-serif; line-height: 19.190340042114258px; text-shadow: none;"><span id="Spark_plug_issues" class="mw-headline" style="text-shadow: none; color: #003366; font-family: 'times new roman', times;">Spark plug issues</span></h2><p style="margin: 0.4em 0px 0.5em; line-height: 19.190340042114258px; font-family: sans-serif; font-size: 12.727272033691406px; text-shadow: none;"><span style="color: #003366; font-family: 'times new roman', times;">2-valve 4.6 L, 5.4 L, and 6.8 L engines found in many 1997–2008 Ford, Lincoln, and Mercury vehicles have an issue with stripped or missing spark plug threads in the cylinder heads. Ford acknowledges this issue in TSB 07-21-2 as well as earlier TSBs. Ford's TSB does not state that this issue is caused by owner neglect. Ford's only authorized repair procedure for out-of-warranty vehicles is to use the LOCK-N-STITCH aluminum insert and tool kit. For vehicles under the New Vehicle Limited Warranty, Ford will only cover the replacement of the entire cylinder head; however, the Ford recommended spark plug service interval extends beyond the duration of the New Vehicle Limited Warranty.<sup id="cite_ref-57" class="reference" style="line-height: 1em; text-shadow: none;"><a style="text-decoration: none; color: #0b0080; background-image: none; white-space: nowrap; text-shadow: none; background-position: initial initial; background-repeat: initial initial;" href="
http://en.wikipedia.org/wiki/Ford_modular_engine#cite_note-57" rel="nofollow" target="_blank"><span style="color: #003366;"><span style="text-shadow: none;">[</span>57<span style="text-shadow: none;">]</span></span></a></sup></span></p><p style="margin: 0.4em 0px 0.5em; line-height: 19.190340042114258px; font-family: sans-serif; font-size: 12.727272033691406px; text-shadow: none;"><span style="color: #003366; font-family: 'times new roman', times;">3-valve 5.4 L and 6.8 L engines built before 10/9/07 and 3-valve 4.6 Ls built before 11/30/07 found in many 2004–2008 Ford, Lincoln, and Mercury vehicles have an issue with difficult to remove spark plugs which can cause part of the spark plug to become seized in the cylinder head. The source of the problem is a unique plug design that is made with a 2-piece shell, which often separates, leaving the lower portion of the spark plug stuck deep in the engine. Ford acknowledges this issue in TSB 08-7-6 as well as earlier TSBs. Ford's TSB does not state that this issue is caused by owner neglect. The TSB provides a special procedure for spark plug removal on these engines. For situations where the spark plug has broken in the head, Ford distributes multiple special tools for removing the seized portion of the plug. The multiple procedures required for the different cases/situations of plugs seized in these engines are explained in the TSB. This repair is covered for vehicles under warranty; however, the Ford recommended spark plug service interval extends beyond the duration of the New Vehicle Limited Warranty.<sup id="cite_ref-58" class="reference" style="line-height: 1em; text-shadow: none;"><a style="text-decoration: none; color: #0b0080; background-image: none; white-space: nowrap; text-shadow: none; background-position: initial initial; background-repeat: initial initial;" href="
http://en.wikipedia.org/wiki/Ford_modular_engine#cite_note-58" rel="nofollow" target="_blank"><span style="color: #003366;"><span style="text-shadow: none;">[</span>58<span style="text-shadow: none;">]</span></span></a></sup></span></p><p style="margin: 0.4em 0px 0.5em; line-height: 19.190340042114258px; font-family: sans-serif; font-size: 12.727272033691406px; text-shadow: none;"><span style="color: #003366;"><span style="font-family: 'times new roman', times;">Federal-Mogul, parent company of Champion Spark Plug, and Brisk Silver Racing have introduced a 1-piece machined shell 3-valve spark plugs that addresses the OEM 2-piece spark plug's separation issues.</span><br><br><span style="color: #000000;">Since E-Series vans use 2-valve heads instead of 3, the problem should only be with the "stripped or missing" threads, not the broken spark plugs. That's encouraging. But I know nothing about the LOCK-N-STITCH aluminum inserts. Is that like Helicoil? Anyone know?</span></span></p>