JP2085

Maybe I'm being paranoid, if so please tell me. But a big reason I didn't buy a V10 and settled for my 4.6 half ton is so I wouldn't have to worry about a spark plug blowing out. At least that is what everybody told me and I understand the blowout problem was fixed in 2003. I also understand the reason they blow out is because the spark plugs have only 4-5 threads. I was looking at spark plugs for my pickup and notice it calls for a Motorcraft SP493. I get on eBay and find this auction showing a SP493 spark plug with only 5 threads.
http://cgi.ebay.com/ebaymotors/Motorcraft-SPARK-PLUG-lincoln-TOWN-CAR-TOWNCAR-93-06-05-_W0QQcmdZViewItemQQhashZitem1e5b57b3f3QQitemZ13038 1493235QQptZMotorsQ5fCarQ5fTruckQ5fPartsQ5fAccesso ries

Are they really like that?? If so, what makes them not blow out like previous years? Kind of pissed off right now.

rtg143

The main reason most of them blow out is due to not torqueing them properly. Too loose and they loosen and come out. Usually without damaging the threads much. They will have to be repaired someday. Too tight and when the aluminum cylinder head expands, it pulls the threads out of the head. The threads have to be replaced. The plugs have to be torqued to 7-14 lb/ft or 84-168 lb/in.

JP2085

Thanks but I understand why and how they blow out. I just want to know if my 2005 is going to be just a prone to a blow out as, for instance, a 2001.

rtg143

Yours is that kind. If you do them right you don't have to be concerned. I've done over 100 of them with no problems.

JP2085

Well I have the SP493s in hand and they are "normal." NOT the stubby kind. That's certainly a relief.

Puto

I just got some plugs for my 2003 Screw 4.6L and the plugs are SP-493 (AGSF32PM). Looking at the threads I certainly see more than just 4 -5, it's actually twice as big.

rnln

thanks rtg143
This is confusing. Multiple people are saying between 22 lb/ft - 25 lb/ft. Some are saying 25 lb/ft - 32 lb/ft. Now I see 7 lb/ft - 14/lb/ft.
I have worked on more than couple cars and honestly Ford is the only one I have read multiple info. like this. I wonder what most people are doing?

redfishtd

The way I understand it is the head has few threads on the early models. The 5.4L 3v 04 to 08 are the ones they call for 25 foot pounds so they won't loosen . Its very important on the 3v to use a torque wrench as they really do loosen , a gas smell in cab with a misfire is classic symptom . I would not put that torque on the early engines with too few threads. So i guess its important to use a torque wrench on all years .
I can't say what that torque is for the early ones . Ford raised the 3v to 25 so i guess you can find different numbers depending on where you look . I went thru the three different broken plugs/bad plugs on the 04to 08, original, then sp515, then sp546. After breaking two original I went to champion 7989 as they proved they would not break , i did try the sp515 but they would fail right out of the box . So I stayed with the champions till this day . I still use nickel anti seize on the snout and 25 foot pounds and change them every 60k .

laterongc

rnln

I see. So rtg143 was talking about pre 04-08 I guess. Thanks for clarified.
BTW, the SP-493 I got from Autozone has thread the whole length as the pics on their website. I do use anti-seize so hopefully it won't break when I need to take it off.