Good Morning All,
I have the infamous COP failure and was going to replace the faulty one with one from the local parts store. I do understand that I should replace them all and will be doing so when the temperature is above 0. Working on my beloved truck when it is -8 is not a fun thing to do.

While I was researching COP on ebay, I found a kit that had all Motorcraft branded parts and came with 8 COP and 8 spark plugs. I was going to get this and then I remembered that the plugs could be a ploblem.

I had a 97 5.4 and the stealship stripped out the threads in the head because the spark plug was corroded.

I currenly now have a 2003 and the plugs haven't been changed. Are the plugs strippng still an issue with this year of truck as well or did ford fix it


Thanks!!!!

 

Replacing all the COPs isn't really recommended.

I bet that ebay listing, if you read it closer, says Motorcraft spark plugs but the COPS are likely Chinese (not disclosed or ambiguous).

Pull all the COPs off, squirt some PB blaster down in the holes, let it soak, then gently work the plugs loose, then back and forth several times. That will usually solve it unless the engine maintenance was severely neglected.

 

I have replaced two COPs so far on my 2004 Lincoln Navigator so I don't think replacing them all is needed unless you don't know which ones are misfiring.

 

The reasoning behind replacing them all is that once one goes the others will soon follow. So it's best to just do them all along with the spark plugs and be good for another 100K or so miles.

 

Does anyone have any information on how long the low priced ebay COPs last? I don't have any data that the cheap replacements will last longer than the current OEMs. Replacing the boots is probably a good thing at the minimum.

 

I'd call that faulty logical reasoning. Just because one fails does not logically mean another or the rest will fail in any specific interval.

I replaced a grand total of two over 8 years on my old 97 5.4.

In three years, I've replaced two on my 6.8L.

Replacing all of them would have wasted a whole truckload of money.

 

No, not really. Do you change one spark plug at a time as they wear out, or do you change all 8 at once every 100K miles or so even though 7 out of 8 might still be good?

Parts have a finite lifespan and once one fails towards the end of that lifespan then others are soon to follow. Granted parts can fail before their time and in such a case, changing just that one failed part is more prudent than replacing them all. But in the case here with the 2003 model in question, the COPs are over 11 years old and are approaching the time when they will start to fail.

 

Spark plugs are "wear" items, COPS are not.

 

If COPs are not wear items, then why would they ever get replaced? Something must be wearing out on them.

 

They don't wear out but they may fail eventually... or not.

A "wear item" is an item that wears out with normal usage, that is, it is expected to be depleted by normal operation. Automotive examples include the plugs, tires, brakes, engine oil, etc.

COPs are no more "wear" items than the ignition coils on your older engines. However, because they are physically mounted down in a hole in the valve cover, they are certainly going to be exposed to greater extremes of thermal cycles which will decrease their service life and make them more susceptible to internal breakdown and failure.

Replacing them as a preventative measure is not unreasonable if one can bear the expense, it's certainly not something that the manufacturer recommends.

 

In other words...they wear out.

 

No, they don't "wear out" since there are no moving parts to wear nor is there any constant erosion or "using up" of the device from normal operation. Some of them fail from the stresses placed on them during operation, notably thermal cycling, others will last for the life of the engine.

The COP is nothing more than an electrical transformer. Transformers don't wear out or get used up from operation but they do occasionally fail.

 

Just because there are no moving parts doesn't mean a part can't wear out. COPs are exposed to extreme heat and cool cycles. This constant expanding and contracting leads to cracking of the plastic housing. This extreme heat also causes the rubber boots to harden, become brittle, crack, and finally leak spark to ground. Then there's the internal insulation within the COP that is under constant EMF and flux that causes an eventual breakdown of the insulating material. So while there might not be actual moving parts, such as linkage or bearings, a COP is just as susceptible to wearing out as most any other component is.

 

I changed the plugs on my '03 5.4 about 5000 miles ago and inspected the cops. The rubber part was still pliable and after cleaning the outside, the whole unit looked new. Needless to say, I did not replace them. The plugs are the non-breakable type unlike the ones that are found in the '05 model, and the 5.4 uses a cast iron head so don't worry about stripping the holes.