Sparkplug Question
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Sparkplug Question
I just bought a 2003 F-150 4.6 2valve truck. How bad is the spark plug breaking problem in this engine? I need to replace a coil pack #8 cylinder and thought I better changes plugs while I am in there. Has about 110,000 on it
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They changed the spark plug torque specs due to plugs blowing threads. I wanna say it is 28 ft lbs now. The manuals say 7-15 lbs but that is why the plugs would come lose and blow out taking out the coil with it. I've always tightened them by hand and then a 1/3 of a turn. So far so good for me.
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They changed the spark plug torque specs...
The 28 lb-ft number came from a repair service company and has been found by a number of other guys, including myself, to be effective in preventing blowouts.
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Since I am recovering from knee replacement, I have decided to take it to the Ford dealer and let them do it. Gave me a price of $350 to replace all spark plugs, fuel filter, and #8 coil pack. All Motorcraft parts.
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Its not an issue on the 2-valve motors, just on the 3-valve. Unfortunately though, on the 2-valves you do have the potential issue of the plugs ejecting.
I had it happen on my 5.4L once. Its easy to fix with a helicoil.
I had it happen on my 5.4L once. Its easy to fix with a helicoil.
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From: KS
For all 2-valve 4.6, 5.4 & 6.8L v8 there was a TSB or memo from Ford that said +10 to the original 15 ft-lb spec. So 25 ft-lb plus anti-seize on threads. I think going 100k miles is too long, I know that's what the OEM says. But I go 50k miles.
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For all 2-valve 4.6, 5.4 & 6.8L v8 there was a TSB or memo from Ford that said +10 to the original 15 ft-lb spec.
I've never seen or heard of and cannot find any record of any such TSB.
So 25 ft-lb plus anti-seize on threads.
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You can do whatever you want but I used to always go 100K and never had any issues. I even went 120K on the factory original plugs (because I was a 23 year old with a house and a $500 a month truck payment who was broke most weeks) and still never had an issue.
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I ended up going over 140K on the factory plugs in my navigator, because unbeknownst to me the original owner never changed them. I changed them only because the engine started having starting issues in the cold weather.
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I hear you. No issue with mine other than I felt like it was due. I do think that on some engines that use fine wire iridium plugs that 100K plug changes are neccesary but Autolite plugs seem to last forever.
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I've been using NGK Iridium's. I also had coil issues and changed over the Granatelli Street Fighter coils. They have both have worked well with all my modifications. I had 3 coils go bad in a matter of 2 weeks so I just replaced them all.
