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Tested for the breaking point on the early 4 spark plug thread heads

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Tested for the breaking point on the early 4 spark plug thread heads

 
  #61  
Old 05-18-2018, 11:28 AM
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Since this seems to be the Modular Spark Plug Knowledge Compendium thread, I'll post in here. I was fully prepped to do the plug change on my truck as I didn't have a full service record to guide off when I bought it. Read all the info, purchased a 3/8" TQ wrench, Motorcraft plugs, etc, etc from all of the reading on here. When I pulled the first plug it was super clean and still looked relatively new. At that point I decided it looked too new to bother going through and replacing all of them so I reinstalled and I have all of the parts to reevaluate in about 30k more miles.

One question that did pop up was, does anyone use anything to clean the threads in the head before installing new plugs? The one I pulled out had a bit of anti-seize residue left in the plug well, which seems like it could throw off torque values and prevent a good clean seat. I was thinking for next time I'd try to find an appropriately sized copper gun cleaning bore brush to use to chase the threads for a fresh start. Good idea? Bad?
 
  #62  
Old 05-18-2018, 01:07 PM
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Originally Posted by maticuno View Post
One question that did pop up was, does anyone use anything to clean the threads in the head before installing new plugs? The one I pulled out had a bit of anti-seize residue left in the plug well, which seems like it could throw off torque values and prevent a good clean seat. I was thinking for next time I'd try to find an appropriately sized copper gun cleaning bore brush to use to chase the threads for a fresh start. Good idea? Bad?
IIRC someone makes a dedicated thread chaser for these motors but I can't recall who--it should be an easy Google search. The question is how to remove anything dropped into the cylinder from this cleaning action? Overall this isn't a bad idea.

When using anti-seize as I do its important to use no more than what it takes to coat the plug threads. I dab a bit onto the plug threads then turn it against a bare finger essentially wiping most of the anti-seize away, leaving the thread roots covered or filled.

I know the plug's platinum coating is supposed to prevent this but I feel better knowing there's something else at work too---it probably helps my case changing plugs every 50K miles without question. To date I've used my method nickel-based anti-seize, 23 ft/lbs torque (derived from threads here on FTE) 6 times, heads ranging from '97 to 2003---no issues at all. Within the next few months I'll do it twice more on two different 5.4 motors paying attention to the plugs and hole threads seeing if an excess anti-seize remains.
 
  #63  
Old 05-19-2018, 12:39 AM
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Originally Posted by JWA View Post
The question is how to remove anything dropped into the cylinder from this cleaning action?
If it's just dried up goop from the anti-seize, it shouldn't harm anything by just letting it get blown out the exhaust valve on startup. When I checked that one plug, apparently I didn't spend long enough blowing out the plug well with compressed air and a few sand particles ended up in the cylinder. I adapted a piece of 1/2" poly tubing to my shop vac and got most of it out. The rest has hopefully come out the tailpipe by now.

Thank you for the confirmation on nickle anti-seize and 23 ft/lbs. That is my plan as well.
 
  #64  
Old 05-19-2018, 04:29 AM
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Originally Posted by maticuno View Post
Thank you for the confirmation on nickle anti-seize and 23 ft/lbs. That is my plan as well.
Your plan on the anti-seize residue is sound and I'm sure you'll apply it to the new plugs carefully. Glad my little bit of info is helpful, that approach has worked very well for me over these past few years.
 
  #65  
Old 05-20-2018, 09:00 AM
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Has anyone mentioned the changes in the spark plug itself?

I just bought a used 2000 F150 witht e 4.6 Triton engine as a farm tuck and it ran a little rough. I purchased new Ford plugs and coils and replaced them and the truck now runs excellent. The old plugs were not original and they came out fairly easy but I did notice that the old plugs were not threaded as long as my new ones. Keep in mind I bought the cheapest Ford brand spark plugs. What I am saying about the plugs is that the new ones had a much longer thread and therefore weaker at some point, than the ones that were in the truck. Since the threads on the old plugs were not as long, there was more metal. Has anyone mentioned this or noticed this? Do you think I should be concerned about future breakages?
 
  #66  
Old 05-20-2018, 10:10 AM
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Originally Posted by cjuedemann View Post
I just bought a used 2000 F150 witht e 4.6 Triton engine as a farm tuck and it ran a little rough. I purchased new Ford plugs and coils and replaced them and the truck now runs excellent. The old plugs were not original and they came out fairly easy but I did notice that the old plugs were not threaded as long as my new ones. Keep in mind I bought the cheapest Ford brand spark plugs. What I am saying about the plugs is that the new ones had a much longer thread and therefore weaker at some point, than the ones that were in the truck. Since the threads on the old plugs were not as long, there was more metal. Has anyone mentioned this or noticed this? Do you think I should be concerned about future breakages?
Were the plugs Motorcraft brand? If they were and you used the plugs spec'd for your year/engine there shouldn't be any issues at all with them lasting upwards of 100K miles. I don't let my own go that long but its a personal preference.

Having read a lot of threads here on FTE about Modular Motor plugs I don't recall any issues relating to the length of the plug threads. Once the plug body bottoms out against the head any threads not already engaged shouldn't have any effect good or bad on the plug staying in place Most every blown plug is due the head plug hole threads being compromised somehow, the plug itself having little to no bearing when/if it will be ejected.

I have read countless times how an off-brand or aftermarket type has caused misfires and performance/driveability problems but very seldom (if ever) do we see a Motorcraft plug with issues that's been resolved by using the off-brand or aftermarket versions.
 
  #67  
Old 05-20-2018, 11:59 AM
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JWA thank you for the comment. The plugs I put in my truck were Motorcraft SP-479 and I was told they were for the 4.6 Vortex engine. What I observed is hard to explain so I will try again The threaded portion of my old plug was about 3/8" and then larger metal. The new pug was threaded about 3/4". Therefore the threaded portion would seem to be weaker and prone to breakage. But I am not concerned because I doubt I will live long enough toput 50k miles on the truck, and the plugs will certainly last that long. I was just wondering if a change in the way plugs were made for this engine would make a difference in the physical strength of the plug.
 
  #68  
Old 05-20-2018, 12:01 PM
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Originally Posted by cjuedemann View Post
I just bought a used 2000 F150 witht e 4.6 Triton engine as a farm tuck and it ran a little rough. I purchased new Ford plugs and coils and replaced them and the truck now runs excellent. The old plugs were not original and they came out fairly easy but I did notice that the old plugs were not threaded as long as my new ones. Keep in mind I bought the cheapest Ford brand spark plugs. What I am saying about the plugs is that the new ones had a much longer thread and therefore weaker at some point, than the ones that were in the truck. Since the threads on the old plugs were not as long, there was more metal. Has anyone mentioned this or noticed this? Do you think I should be concerned about future breakages?
There was a point in time, model year 2002 I believe, where ford changed the length of the threads in the heads. After that point, the spark plugs that were manufactured were all "long thread" plugs. If you had short-thread plugs in there, they are indeed very old. But breakage? Don't worry about it.
 
  #69  
Old 05-21-2018, 12:59 AM
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Originally Posted by Krewat View Post
model year 2002 I believe, where ford changed the length of the threads in the heads.
M/Y 2003, anything with a build date of November (possibly October, whenever Job 2 went into production) 2002 and newer.
 
  #70  
Old 05-26-2018, 11:47 AM
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Originally Posted by econovanfan1 View Post
New here and soaking up info ... sounds like no major problems on a 2003, 5.4 2V engine as long as you torque them down 20-25 ft/lbs .... Glad to know this!!
I don't think the problem is only the torque of the plugs.
The low torque used on OEM plugs was a contributing factor to plug blowout.
The plugs are subjected to hammering from cylinder compression pulses so plugs that are changed at 100k see twice as many pulses than plugs changed every 50k.
Plugs with a higher torque will take longer to work loose.
Heads with 4 threads just means there are fewer threads to strip or hold the plug in when it works loose.
Also, steel plugs and aluminum heads have different coefficients of expansion from heat which is a factor in loosening of the plugs.
Plugs with 100k vs 50k have possibly twice as many thermal expansion events based on driving habits.
Change plugs at 50k, torque to 20-25 ft/lbs and loosening issues should be minimized.
The boots are probably due for a change at 50k, too.
 
  #71  
Old 05-26-2018, 11:59 AM
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Originally Posted by R&T Babich View Post
The plugs are subjected to hammering from cylinder compression pulses so plugs that are changed at 100k see twice as many pulses than plugs changed every 50k.

Change plugs at 50k, torque to 20-25 ft/lbs and loosening issues should be minimized.
The boots are probably due for a change at 50k, too.
I can't agree any more with all this ^^^^!

Partially due I'm 67 y/o and just cannot believe plugs are still good at 100K miles. There's been a few ersatz reviews, comparisons and such about 50K vs 100K, most reporting there's virtually no difference. I won't argue that point but since plug changes on my vans happen maybe every three years and the cost is relatively low its not something I mind doing. If there's an added benefit it gives me a reason to poke around the engine bay looking for known or potential issues that can be prevented with periodic checks.
 
 
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