I need to change my spark plugs on my '99 GT with 113K.

What year had the spark plug blow out problem the most?

I forgot which it was.
Lynn

 

Anyone?
Lynn

 

I know 99 are on that list.
My guess is it all 4.6 Liters 2V do to few threads in the design of the heads.

If you torque the plugs to factory specs you shouldnt have any problems with them blowing out.

JM2

 

99-03 heads all have less than desirable amount of threads for plugs
04's have more threads but have still been know to spew out a plug

 

i thought the 99 aluminum 4v blocks (cobras) had that problem more than the others

 

They all have the "problem" when the plugs have been replaced and not properly torqued.

The reduced thread count was a good design to minimise the possibility of siezing in plugs that would be only changed every 100k miles--it fell apart in the field, when put in the hands of "I don't need no stinkin' torque wrench" mechanics.

If you absolutely must replace the plugs with out a correctly sized torque wrench (1/4" drive 200lbin max is best) then make them hand tight plus 1/16th turn...

 

A couple of good replies already on this.
Not much you can do anyway if you have one of the poorly designed heads. It is always a good idea to properly torque the plugs in to prevent damaging the threads or leaving them too loose.

Buy or borrow a micro-torque wrench(2-20ft/lb) for the job. I always torque my plugs to 15ft/lb. Since there is a known issue with plugs in these cars, it is worth the "trouble" to find a torque wrench and use it. Also, buy a piece of fuel hose and slip the plug into it to be used to start the first couple of threads by finger. These small steps can save you a major headache later.

GOOD LUCK!

 

ouch, i'm one of those guys... guess i should re-adjust them before i start doin some damage.. if it makes me sound any less ignorant, my friend who is a ford mechanic told me the "i don't need no stinkin' torque wrench method!" was fine. guess i'll hafta school him now

 

As a fellow mechanical engineer I must again put forth that the heads were not poorly designed, but rather poorly maintained. The shop manual is quite explicit about torquing the plugs¹, like Trueblue' I tend to set the wrench at the high end and use 170lbin (14.2lbft).

That many people (including more than just the one Ford mechanic reported by Trailor) do not torque them is not the design engineer's fault.

--------------------------------------
¹ - 11lbft is the spec from Ford, most plug manufacturers say 11-13.

 

All of the Windsor 2V heads are the worse offenders of which the 99-00 GT are included. They have an issue with the factory threading and with the heat treating. You never hear about this problem with the 91-98 Romeo and 4V heads which were also 5 thread.