Bummer!

     I alluded to this in an earlier blog, but my No.7 spark plug blew out of the engine in my Crown Victoria while driving to our shop in Gardena a few weeks ago. Since I wasn’t too far away, I limped it to the shop to investigate the problem and consider my options. I’d heard of this being a common problem with the SOHC 4.6 V8’s. The consensus among the people I’ve asked is that there aren’t enough threads in the cylinder head holding the spark plugs in. Over time, the plugs can back out to the point where they can shoot out of the engine, usually destroying the threads in the head in the process. Sure enough, the threads on my plug were munched and a new plug wouldn’t thread into the head. We didn’t have a 14mmx1.25 tap at the shop, and I resisted the urge to force a new plug in. Instead, I called for a ride home.

It turns out that this is a really common problem.  There are entire websites dedicated to people documenting their tails of spark plug woes and others offering fixes, usually with some sort of thread repair kit, some more dubious than others. Officially, Ford recommends replacing the cylinder head when this happens. I called an area Ford dealer and nearly hung up on the guy when he gave me a ballpark estimate of $2,500 to R&R the cylinder head. Way too rich for my blood.

I did have other options, of course. I could buy a new cylinder head for around $800 and replace it myself, or I could get go the po’ folks route and pull a head from the junkyard for about $250. However Ford did issue a Technical Service Bulletin describing a factory-approved thread repair, and I ultimately decided to give that a shot.

I got the kit last week, and have been working on it sporadically over the last couple of days. We’ll do an article in the magazine showing the process indepth, but basically, you drill out the old threads, tap new ones and screw in a new thread insert. So far, things are going smoothly. Hopefully, I’ll be back on the road soon. I miss driving the car.