I really can't see how torquing the plugs to 28ftlbs is going to prevent them from popping out of the block. If the threads are weak and tend to shear, putting mor torque on the plug will just weaken them more I would think.
I guess it depends on the price of the truck. If its a good deal, then $500 to get a repair made wouldn't be the end of the world. If you're driving it long distances though, the potential for getting stuck somewhere for me wouldn't be worth it.
Well, of the most part, this is going to be an A-B truck for trips to HomeDepot, furniture stores, dirt lots, etc. I seldom see it being used for long trips, though I suppose that could change in the future.
In calling and talking with my mechanic, the spark plug thing seemed to be a non-issue in his opinion. He's dealt with them, but it wasn't much of a problem.
I am trying to figure how big this issue would be compared to a transmission issue or similar. In other words, is this problem a bigger deal than a different problem I would find on a different vehicle. As it is only a $4k (pre-haggle) truck, I would have to expect problems to surface.
The way I am looking at this right now is that the insight you guys have given me may serve as a good notion for preventative maintenance. IE - If the truck sounds good, drives good, etc, I could buy it and then take it to my local Ford dealer and have it looked over and have the spark plugs replaced by them. Then, just make sure to have them replaced every 50-75k miles. Or perhaps have my mechanic do it. He's always been sure to let me know if something crops up with a repair they've done, they'll take care of me.
I guess the big question is, at $4k and the kind of shape it appears to be in, is this potential issue worth risking. From what I've read here:
http://www.walleyecentral.com/forums/archive/index.php/t-159880.html and other places, it seems that aside from this particular issue, these engines commonly see 250k+ miles. Many comment on their F150s being bulletproof and that sort of thing.
The consensus on the torque idea seems to be that it only threads in 4 turns instead of the standard 8. The factory specs originally suggested 14ft/lbs of torque, but the problem with that is that it was just enough, and if someone didn't apply that amount, the plug would come loose, rattle about, and eventually blow off. By applying torque to 28ft/lbs, it does not come loose and thereby does not rattle about and blow off. Basically, if not torqued enough, eventually shock will cause it to break free and set freely in the threads (not tight). Apparently shock won't be enough to break the "seal" of higher torqued plugs. This is just hypothesis on my part, but it sounds like the threads of the hole are fine until the plug comes free and destroys them. Question 51 of this page (
http://www.blownoutsparkplug.com/faqs.htm#Q: Why do you prefer 28-32 foot lbs torque instead of the factory specification) suggests what I've found. With original equipment, 10 Ford Master techs have concluded that 28ft/lbs is satisfactory, and have even gone so far as to apply 100ft/lbs without failure.
I guess at this point, I am still leaning towards taking a look at it. If the engine sounds quiet, then it should be safe to assume that a plug hasn't blown out.
Long story short, the information you've given me at least sets me down the path of investigating or doing something immediately upon taking ownership of the truck if that happens. As it is, with as many of them as I see driving about, I have to suspect that the problem isn't terrible, and most mechanics have figured it out and have some method of correcting it.