Don't use anti-seize on modern spark plugs

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SkooterG

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Taken from another forum:

From Design News Magazine -

We had a 2001 Dodge Caravan with a 3.8 engine and a little over 118,000 miles come into our automotive shop. Intermittently it was hard to start. When it did start, it ran rough, misfired, and sometimes under a load, it would even backfire through the throttle body.

We tested fuel pressure, crank and cam sensor signals and scoped both these sensors, at the same time confirming they were in sync and the timing chain was sound. After some experimentation, we found we could get it to act up by power-braking the engine and running the RPM between 1,500 and 2,000.

The most challenging of these symptoms was the backfiring through the throttle body. For this to occur, combustion has to take place in a cylinder while the intake valve is open. This led us to take a close look at the spark plugs. On plug number three, we found a carbon track where the spark was jumping down the side of the plug. For this reason, we decided to pull the plugs for close inspection.

We found excessive amounts of anti-seize compound on the threads. This vehicle has a DIS ignition system, which uses the threads of the spark plugs as an electrical conductor. We later found out the owner of the vehicle installed the plugs six months earlier and used anti-seize compound. We installed new plugs and cleaned the threads in the heads, and the problem was solved.

We were still curious and confused. How could using excessive anti-seize compound cause the engine to backfire through the throttle body? We checked with three different spark plug companies to see what their ideas were on this subject. All three of them recommended against the use of anti-seize compounds.

They told us they already put a tri-valent zinc dichromate plating on the shells of their plugs to prevent the steel threads of the spark plug from seizing in the aluminum of the cylinder head. They also told us the problem with using oil or anti-seize on the plug threads is that it affects the torque setting. With aluminum heads, it is an important aspect of spark plug service these days to use your torque wrench to accurately tighten the plugs. NGK said that the concern is the threaded outer shell of the plug. If you overtighten the plug, there is a danger of stretching or even breaking the threaded portion of the plug.

They also told us that their recommended torque setting can be misread by as much as 40 percent if the threads have been greased or lubed prior to installation. The danger is not so much that the plug will break, but rather that it will be very difficult to remove the next time around.

They pointed out another problem. Many anti-seize materials come in a jar with a brush built into the top. With such an applicator, it is very easy to put too much goop on the threads. When this happens, installing the plug will effectively pump the excess material either toward the spark gap end or the spark plug wire end of the spark plug. The likely story is that it will do some of both.

Anti-seize compound is basically a mixture of grease and metal particles. Aluminum, copper, and zinc powders are commonly used. The way this works is that whenever you have two different metals, in this case the aluminum of the head and the steel of the spark plug shell, you can set up a battery action if there is an electrolyte between them. This is called a galvanic cell. What happens is that you get a transfer of metal that could cause the plug to effectively weld itself to the cylinder head. Putting the metal particles between the threads of the plug and the threads of the head gives the galvanic cell something to work on rather than the materials of either the head or the plug shell.

Anti-seize works in the same way as putting zinc on a garbage can, which is called galvanizing. It prevents rusting. The zinc sacrifices itself to the rust reaction, leaving the steel protected. The downside to anti-seize is what happens when too much of it is used. The grease and the metal particles can wind up in places where it not only doesn’t help, but it can actually interfere with the operation of the plug and the engine.

Several things could result from such contamination. The central electrode of the spark plug has a ceramic base that insulates it from the steel shell of the spark plug. To the extent that this is covered in metal particles and grease, it gives an unintended path for the spark. Instead of the spark being in the right place across the electrodes, it could wander off down the side of the plug. This can result in a misfire or even a late firing event.

To the extent that it is the grease that covers the firing end of the plug, this can cause a no-fire condition. Excess fuel fouling of the plug can cause much the same situation. When we look at these plugs, what we see is that we have deposits on the ceramic insulator that do not belong there. We can also see anti-seize residue on the threads and at both ends of the threaded area.

In modern ignition systems, the coil is typically capable of producing more than 35,000 volts. That is almost double the capability of the old, round cylindrical oil-filled coils used years ago. When this voltage cannot jump the spark gap, it will find the next best path to ground.

With this car, we also saw another installation problem. Plug number three had a cracked ceramic insulator. This too can be caused by excessive installation torque. The high voltage arced along the ceramic of the plug and hit the ground shell. Under a microscope, you can see a burn mark on the steel shell.

We also found the spark left carbon tracks on only the tops of the insulator ribs. This means the material of the boot didn’t settle down into the bottom of those ribs. Boot grease serves at least three purposes. It prevents the boot from sticking to the plug, but it also allows the boot to settle in and form to the shape of those ribs. The ribs are here to make the path the spark would have to travel longer. The grease also fills the gap between the boot and the plug to prevent that from becoming a gap that the spark can travel along.

When we examined this wire set, we found that the grease had not been installed. We see this quite a bit. Oftentimes service techs, and especially do it yourselfers, do not really appreciate why we put those grease packets in the box with our wire sets and ignition coils. That grease really does need to be there.

In looking at these wires, we also noticed a lot of grease and other contamination. It is probably worthwhile to remind you that we are trying to hang on to 35,000 volts here. That is not easy to do. It is important to use the boot grease, put the wires into their plastic holders and separators, and keep the outsides clean and dry.

One last comment -- if you really do want to use the anti-seize material, go ahead. Just keep the advice from the spark plug makers in mind. You need to limit the amount of anti-seize you put on the plug. This is one of those deals where a little dab will do ya, and more won’t help you. Don’t let the anti-seize material get in the wrong places.

Take the time to grease the boots, and make sure the plug wires are properly installed. Finally, be carefull when you tighten the plugs. The spark plug companies want you to reduce the amount of tightening torque by about 40 percent. If you don’t, you run the risk of cracking the ceramic and/or stretching or even breaking the threads on the plug shell.

This entry was submitted by Mark Hicks and edited by Rob Spiegel.

Mark Hicks is an ASE Master and L1 certified. He is an independent shop owner of 15 years, and he has spent 18 years working for Wells Vehicle Electronics as a technical services manager

 

FJRay

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Good article. The only thing I see that is wierd is that they make a point of saying that the plug body is part of the electrical path like it's something new. I've been in this trade for 45+ years and haven't seen a plug that the body wasn't the ground path. There may be but I haven't seen it.

I still use anti sieze but only in small amounts. I have seen lots of plugs sieze in aluminum and it can be a real spendy repair in some cases. I have also had plugs sieze in cast iron heads to the point where they break off and leave the threads in the hole, another pain in the ass to fix.

I gently tighten plugs with a gasket and for plugs with a tapered seat I just seat them with wrist pressure and thats it. YMMV.

 

Spud

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Quote by "Jestal" https://www.fjrforum.com/forum//index.php?showtopic=7726&st=0&p=92771entry92771

"By the way, the antiseize is used primarily to prevent corrosion between the two dissimilar metals causing the threads to jam. Aluminum threads in the head are subject to galvanic corrosion when steel spark plug shells are threaded into them and a corrosive environment is created by moisture, salt water, etc. The premium plugs, such as the iridium plugs that most people use in the FJR and the dual platinum plugs used in auto engine OEM applicaitons, are generally nickel plated on the shell and threads to prevent corrosion and alleviate any concerns with plugs seizing. Since the iridium and dual platinum plugs are meant for long life (easily over 100K in auto engines) they will be in for a long time and thus are protected with the nickel plating on the shell for this reason. Antiseize on a nickel plated spark plug shell is totally redundant overkill. Totally."

 

Geezer

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I agree with Ray. A little dab of anti-seize will do the job, and keep it away from the end of the plug.

I have never used a torque wrench on a spark plug. Many years ago I'm sure that I over torqued a few, but these days I tighten them down enough to crush the gasket and no more.

I'm not sure when the plug manufacturers started using the coating that prevents seizing, but I did have a factory installed plug seize in an aluminum head on a Cadillac I used to own, and I ended up pulling the head to fix it, so I plan to keep using a little anti-seize.

 

TomInPA

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I have always used very small amounts of anti-seize from a small tube, worked into the upper threads and I use a torque wrench to set the plugs. Never experienced a problem with the plugs with this method. The article is probably correct that the use of this material is not necessary with modern plugs, and I may skip it next time. The actual operating problems and seizing seem to stem from the use of excess compound that creates a short-path from the electrode to the plug body. Obviously if you are clueless and smear conductive material on the insulator and bottom of the plug, there will be a problem.

 

Panman

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I can tell you that that Plug has a real long set of threads. My wife's Mini Vans when I changed these plugs had me worried as they came out hard all the way. I put a dab of anti-seize on them just to insure that I could change them again next time.

 

wmadoty

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I like the article and it is very interesting. Thank you very much for posting this. While I value your opinion and respect it, I would like to disagree.

One thing I noticed from the article was that in addition to large amounts of compound causing a problem in this vehicle they found a cracked insulator. I suspect the cracked insulator was a much bigger problem than the over application of anti-seize. I agree that both can be a problem.

I have always used a little dab of anti-seize when joining dis-similar metals or joining surfaces that get real hot (exhaust bolts, oxygen sensors, etc.). This procedure has served me well and I can not see changing my practice anytime soon. I have drilled and tapped far to many untreated bolts to change my mind. On my FJR that means that almost every fastener I pull gets something put on it.

I have no doubt that plug manufactures have made improvements to the metals and metal coatings they use, but I am not convinced these improvements have gone far enough, and my experiences have shown me that they do not work well enough. I do not feel safe not treating a plug.

After Squeals problem with his 2007, (Squeals Problem) ask him if he puts the juice on his plugs in the future. How many of us have removed the lower brake caliper bolt and applied a generous amount of the magic paste to it? Moderation seems to be the key with plugs. Moderation and torque restraint, and a healthy dose of common sense.

 

RPrice

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Can't believe this hasn't gone to NEPRT yet!! There's countless threads dedicated to this subject (on this and other forums), and nobody seems to agree.

 
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AlleyCat

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Good post... Since I have started using a torque wrench, I realized I have been over-doing it with the power. I am aware that torque wrenches can be 'off' also and I don't send mine in every other year to get calibrated. I do take care to not drop them and I don't use the torque wrench to 'break' (loosen) items. At least I am playing safe and minimizing the risk.

 

UselessPickles

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Can't believe this hasn't gone to NEPRT yet!! There's countless threads dedicated to this subject (on this and other forums), and nobody seems to agree.
But this one is a technical explanation based on discussions with the plug manufacturers themselves. I guess some people will never believe the experts and will treat their recommendations no different than the opinion of a forum member.

 

RPrice

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Can't believe this hasn't gone to NEPRT yet!! There's countless threads dedicated to this subject (on this and other forums), and nobody seems to agree.
But this one is a technical explanation based on discussions with the plug manufacturers themselves. I guess some people will never believe the experts and will treat their recommendations no different than the opinion of a forum member.
Yes, I think you hit the nail on the head by saying, "Some people will never believe the experts and will treat their recommendations no different than the opinion of a forum member." That's why these issues never get resolved...............for everybody.

BTW, I believe the experts and the plug manufacturers and DON'T put anti seize on my plugs. And I've never had a problem. Go Figure!

 

SQUEAL

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I am sure they are correct about the van. Sounds good to me! I am really glad this never happens to un-sleazed plugs. It would be a shame if it did. :blink:

 

wfooshee

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The only plug failure I ever had was a plug that backed out after it had anti-seize applied. I was told I "had to" because they were going into aluminum heads. I've never used it since, and I've never had a plug problem.

Nor do I torque spark plugs. You know when a plug is tight. It stops turning. Don't go any more when that happens. EZ!

 

HotRodZilla

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This is actually good to know since I didn't use any anti-seize when I changed my plugs. I've been a little concerned after reading some others' horror stories. Now I feel better...

 
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TomInPA

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As far as plug torque, the spec for the FJR is just 9 ft-lbs (108 in-lbs). Using a torque wrench, I find that ensures the crush washer sets, and the torque is set. If you have the feel for that, then good, otherwise, hacks like me are better off with the wrench. Before using the torque wrench, I was seating the plug, but not getting the washer to crush, so I was seriously under-torqued. With as deep as the plug is inset into the FJR head, it seems like setting the torque properly is the "right way". YMMV.

I think it's great that you have the "feel" to set bolts with out a torque wrench, but it's not something I would advocate on a forum, even if I thought it could be done reasonably accurately.

 
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