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Spark plug question

2192 Views 9 Replies 3 Participants Last post by  budman451
One of our trucks has the V10 in it. On the way in to work yesterday morning, the fourth plug back on the passenger side blew out.

Big bang, followed by lots of little bangs....

Disconnected the coil, pulled the plug, and the first couple of threads on the end of the plug are bunged up.

With lots of sticky oil to hold on to shavings, I run a tap through the head - it runs through and back with no problem, but I can't get a new spark plug to thread into the hole.

Any ideas on what to do next?


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Two choices, Ford recommends to replace the head, as when the plugs pull out it takes the threads with it, you may have "some" threads left, but not enough to keep a plug held in there.

The second option is to install a Timesert(similar to Heli-coil, but different), Ford does not recommend head repair, but this can be done in chassis carefully, and there are many Ford techs/dealers and independent shops that have done this with great success, but most will not guarantee anything with it. Cost of doing the Timesert is somewhere around $300 for the kit plus the time of repairing the spark plug hole. Timesert website

Labor time to replace the cylinder head is approximately 12 hours, plus the cost of the cylinder head. When I replaced the heads, they also got 10 new spark plugs, one new coil, as the coil tends to break the mounting ear off, gaskets, oil & filter, coolant, and usually some other miscellaneous items that may be found to be damaged/worn from normal use such as hoses, timing chains/guides, and the COP boots.

Yes, this is somewhat of a common problem, and every V10 that I have done head replacements on because of plug blow outs, it has always been cylinder #4, fourth back on passenger side every time. Somewhere in 2001 or 2002 there was a casting/machining change to increase the number of threads from 4 to 6 or 8 to help prevent that problem.

The Triton engines is one of the very few engines where I will demand only OEM parts and procedures. I very strongly recommend only the Motorcraft plugs, as they are supposed to have a coating on them, so no anti-seize should be used on the threads, where I do not see anything like that on aftermarket plugs. IIRC, 13 ft. lbs. is the torque spec on the plugs. The threads can be stressed easily in the head from overtorqueing or blown out from undertorqueing, so a good torque wrench is mandatory on these engines IMO.

The problem did not completely disappear after 02, it was still there, just seemed to occur much less. With the new 3v design V10 in the 05+, including the engine that should be in your future new 08, I have not seen any major plug blowout issues with them.

Problems that I've seen fairly common, at least with the 05-07 Super Duty V10 platforms, mostly consisted of slow fuel fills caused by a plugged EVAP canister especially around here where the oilfield roads will plug them up quick with dust, false overheats, engine stalling/no response caused by a bad TPS or throttle body assembly. There were also quite a few problems with instrument clusters and some problems still with the rear wheel speed sensors.

Most of these concerns have TSB's out on them. As to how many of these problems may transfer to the new 08's, I am not sure. I left the dealer back in February and only dealed with one new 08, and that was a plain jane XL 5.4 that I did a PDI on. I never read too much in the 08 WSM or PC/ED's to see how much stuff was changed to see if any of the common problems may carryover.

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