Spark Plug Wires?
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Spark Plug Wires?
When is a good time to replace the spark plug wires?
The truck has 75k miles and I'm not the first owner, so I have no idea if they were ever change before, and how can I tell if the ones on the truck are the original Motorcraft brand?
The truck has 75k miles and I'm not the first owner, so I have no idea if they were ever change before, and how can I tell if the ones on the truck are the original Motorcraft brand?
Fleet Mechanic
Joined: Dec 2003
Posts: 1,436
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From: Virginia
My new Motorcraft wires were med-gray and I believe they said "Motorcraft" in black on them.
Plug wires "can" last a long time, but it all depends on what they were subjected too. Even a "newer" set of wires can need replacing if some lug-nut pulled on them instead of the boot to change the plugs.
I would do a complete inspection of them from end to end to see if there is any sign of damage or wear. I know some people like to pull the wires and look at how full the spark is. I don't recommend it, but that's me since I am prone to injuring myself doing stupid things.
Plug wires "can" last a long time, but it all depends on what they were subjected too. Even a "newer" set of wires can need replacing if some lug-nut pulled on them instead of the boot to change the plugs.
I would do a complete inspection of them from end to end to see if there is any sign of damage or wear. I know some people like to pull the wires and look at how full the spark is. I don't recommend it, but that's me since I am prone to injuring myself doing stupid things.
Posting Guru
Joined: Dec 2003
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From: Maine
I'm thinking that the original Motorcraft wires have a Ford oval printed on them near one end, and I'm fairly certain they've got numbers printed on them that correspond to the cylinder the wire goes to.
I replaced the ORIGINAL ones in my truck at 210k miles. I know the guy who bought it new, and he swears up and down he never had the plugs or wires changed in the 200+k miles he drove it. They looked like hell, and I'd bet it wasn't actually firing all 8 plugs, but at least 1 per cylinder was still getting enough juice to make it go.
If I'd just bought your truck, though, I'd probably put new Motorcraft plugs and wires on it, just so I knew when they were done.
I replaced the ORIGINAL ones in my truck at 210k miles. I know the guy who bought it new, and he swears up and down he never had the plugs or wires changed in the 200+k miles he drove it. They looked like hell, and I'd bet it wasn't actually firing all 8 plugs, but at least 1 per cylinder was still getting enough juice to make it go.
If I'd just bought your truck, though, I'd probably put new Motorcraft plugs and wires on it, just so I knew when they were done.
Post Fiend
Joined: Jul 2005
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From: Durant, OK (SOSU)
Mine say Motorcraft on them, I do remember they looked the same as the ones that came out, so I'd assume those said Motorcraft on them, too.
75K is probably about right...100K is the "recommended" interval by Ford...but many have issues before that. You'll probably notice a nice change at 75K just by putting in new plugs and wires and gapping the plugs correctly.
75K is probably about right...100K is the "recommended" interval by Ford...but many have issues before that. You'll probably notice a nice change at 75K just by putting in new plugs and wires and gapping the plugs correctly.
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OK!
I got the Motorcraft ones, I'm sure they're original form day one, they're gray with numbers on them, they look fine to me, no cracks or torn boots, so I'll skip the plug wires
and keep searching for another problem that is doing the "pinging"
I got the Motorcraft ones, I'm sure they're original form day one, they're gray with numbers on them, they look fine to me, no cracks or torn boots, so I'll skip the plug wires
and keep searching for another problem that is doing the "pinging"
Post Fiend
Joined: Jul 2005
Posts: 8,462
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From: Durant, OK (SOSU)
Go ahead and run it at night with no lights on (including the underhood light) to see if they arc.
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Originally Posted by RangerPilot
Go ahead and run it at night with no lights on (including the underhood light) to see if they arc.
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From: Denver
A little water sprayed on the wires will help identify the arcing also.
BTW, I had my truck on the dyno at 76k miles w/ factory plugs & wires and it put out over rated power. I put on new plugs, wires, and headers and the new dyno numbers were slightly lower than before. The reality is that the ignitions on these units are very strong, and you really can go 100k+ miles if you want to before changing plugs and wires. Anywhere over 75k, I'd change both plugs and wires together, as the most likely damage to the wires occurs when you pull them off the plug.
BTW, I had my truck on the dyno at 76k miles w/ factory plugs & wires and it put out over rated power. I put on new plugs, wires, and headers and the new dyno numbers were slightly lower than before. The reality is that the ignitions on these units are very strong, and you really can go 100k+ miles if you want to before changing plugs and wires. Anywhere over 75k, I'd change both plugs and wires together, as the most likely damage to the wires occurs when you pull them off the plug.
You want me to get electrocuted? 
Cargo Master
Joined: Feb 2002
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From: Tucson USA
One of the first things I do personally on purchase of a used vehicle is to change all he fluids and replace plugs and wires. Then you have the peace of mind that everything is right (hopefully). You can get a good set for $30-40 or you can get real expensive. I just put replacement autolites in mine and have almost 160K on the wires, change the plugs annually along with trans, rear end fluids. antifreeze every 2 years. Truck has 240000 on it, 60000 when I bought it.
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