Spark Plug Boots?

Paul G

Active Member
Jun 10, 2013
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On a 2005 - 2009 GT, I always assumed that the coil packs included the spark plug boots and that the boot was not sold separately.

I've got a quote from the Ford Dealer to change plugs, boots & wires, but when I questioned "boots", I asked, do you mean the coil pack&boot? He said his computer just says boot.

I called Summit Racing and they state that they don't sell the boots separately, their part of the entire coil pack.


Q1. Are the boots sold separately?

Q2. Why would I just change the boot and not the entire coil pack (coil & boot) as well?
 
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I've never seen (or even heard of) a two piece coil pack before. My guess is that the Ford dealer was looking up the incorrect application. I think the 6 cylinder Mustang might have a weird plug/wire/central coil pack setup. Double check the dealer for the proper application, or maybe look into buying aftermarket coils. MSD, Accel, or GMS all manufacture coils with much more voltage than stock.
 
well after doing some digging on the Fort Parts website, I found part #12A402 (Spark Plug Boot).
I've also got a concern because the dealer quoted me $19.16 per plug.... I searched Ford Parts, and the only plugs that are $19.16 (and the only plugs that came up for my VIN) are 12405(SP-462), which are the Ford Racing Zero Degree plugs.

I was under the impression that unless I've added a supercharger or nitrous, I should not use the Zero Degree plugs.

I have more questions than the dealer can give me, and that makes me nervous....
 
It wouldn't be a huge deal to use these plugs. Running colder heat range plugs can cause carbon fouling at low engine speeds, but if you're planning to modify the engine at a later date, it wouldn't hurt. If not, and the Ford dealership doesn't carry anything else, I'd simply run to an auto store and pick up some Motorcraft or Champion plugs. Just make sure and pickup single piece plugs. The two piece plugs like to snap off in the cylinder head.
 
The answer about coil packs vs just boots is the coil pack itself tends to last a long time. But the boots dry and shrink, cause a bad seal. Moisture can get into the spark plug hole and cause misfire. The only thing wrong tends to be the boot, not the coil pack.
 
I've never really examined them very closely, but how do you replace the boot?
They just pull off the coil itself. There is a barb holding them on. The new ones push over the barb and stay in place. I always use a very thin layer of spark plug boot grease there and a good amount of the same grease right where the boot seals to the head. That helps keep water out. I like to coat the whole flare/flange with the spark plug boot grease to protect it. One it dries and shrinks, the problems set in.