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Blown Spark Plug


My 97 just blew a #4 spark plug today with 88,500 miles. I had them replaced in January. Has this happened to anyone? If so, what did you do? Thanks.

97 TR Welded at 87K For Sale
99 TR 34K Not welded yet but soon
I think someone on list has successfully installed a
helical to fix a blown plug.


'98 TR - Poor man's intake
'96 TR - Welded, FPS tuner, Copper motorcraft plugs, Poor man's intake, Opened stock exhaust for that V-8 burble
'89 Black - MTX drain plug mod, Redline MTX fluid, RIP
'01 E-450
'06 Rendezvous AWD
'07 DTS

Yeah I had that happen, very simple tap the hole out, put the heli coil in, no problem. Mine snapped the coil on top of it so i had to replace that to.

Benjamin James
You mean #4 as in the one closest to the speedometer?

Do you know yet what really happened to it? My V6 SHO blew out a spark plug one time, but it blew the ceramic center out of the plug and left the steel outer sleeve in place. I just unscrewed that with a standard spark plug socket and put in a new plug.

On the car or off the car was the HC installed?

Kirk J Doucette


SCT Dealer.
Are the threads gone or did the plug just back out? Could be they just
left it loose, did it push the coil pack all the way off and strip those
threads too? If they left the coil screws off also, it may be as simple
as putting it back together?

Don Mallinson
When it ejects it wipes out the coil fairly well.

Always inspect each plug before install!. 1 small burr on the plug and it
will wipe the head out!

Kirk J Doucette
SCT Dealer.
I have a renewed interest in the Ford plug issue as I have one of the older 5.4s
that would blow out plugs on occasion.

In checking the Service Manual, it is interesting that Ford "only" calls for
80-178 lbs/in for the plugs, which is approx 7 - 15 lbs/ft. What is the torque
spec for a 3.4 plug?

I have never used a torque wrench when installing plugs, but it looks like it's
time for a lbs/in wrench, as I know that I have never installed a plug with a
torque setting that low.

Ron Porter
If I'm not mistaking, the torque spec for a 3.4 plug is 10 -16 lbs/ft. according to Lucien.
I use only a hand T wrench on aluminum head engines to
install plugs. Way too easy to over torque them.

Jim Heaton

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