Yes through the threads which make metal-to-metal contact. If they are not making contact then there is an air space anyway, and air is an effective dielectric. Grease does not change this. No conduction is made in that threaded joint except where the threads make actual contact.
anti seize on spark plugs
- Thread starter The motor guy
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This is not the place for dielectric grease. Dielectric grease is far more likely to inhibit conduction than a layer of air, which is minimized on torquing.
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I use it on spark plugs.
So you are saying the electrical conduction in the thread spaces occurs across a spark gap? No it does not.
So much confusion on the subject of dielectrics in electrical joints. It helps if you understand they are everywhere unless there is actual metal contact. You're not inhibiting conduction in any way since you do not understand what's going on.
The plug needs to be grounded.
Air does not adhere to the metal preventing M/F thread contact like a grease would. Air is technically not an insulator either - its just a really, really poor conductor because molecules are spaced far apart.
di-electric grease is in fact an insulator. Its more than likely enough metal contact on a thread would occur or the film would be too thin to insulate anything, but technically its still a poor idea. If you want to use grease on something that is intended to conduct use a conductive grease.
Here is a higher resolution cross section. Take a look where the threads make full contact and where there is an air gap. That’s where the antiseize or any other lubricant migrates because it’s squeezed out and will not prevent full metal on metal contact.
That’s why a lubricant has no effect on conductivity.
That’s why a lubricant has no effect on conductivity.
This is entirely wrong on every level except for your statement that the plug needs to be grounded. You should not use a conductive grease in this application. Those are used only in very specific applications where migration is strictly controlled. Actually there are few of them, thermally conductive greases are far more common.
The plug is grounded and the dielectric grease makes no difference. I am not advocating using it as an anti-seize here (which it is not) but it won't inhibit electrical conduction in any way.
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Yes I always use anti seize on spark plugs. Once you’ve had to get a breaker bar and pipe out to take them out you will too. Also I put dielectric grease in the boot.
That's not true. I understand exactly what is going on here. You have asserted that there is a misconception about how spark plugs work regarding the flow of electricity through the threads. You and others have shown diagrams indicating that, essentially, there is plenty of contact on the actual side of the thread that is held in tension against its counterpart. The "other" side of the thread constitutes a "space" and I suppose you are saying that any antisieze or grease, or air migrates to that space. I would point out that antisieze works by minimizing metal-to-metal contact. I would suggest that dielectric grease works the same way. My argument would be that the presence of a dielectric immediately reduces some contact, and may degrade over time.
All of that notwithstanding, the age-old question is whether there should be anti-sieze on sparkplugs. Many posts have beaten this issue to death, and I think we are in agreement (?) that the plugs are manufactured as to not require anti-sieze or lubrication. As in so many cases on BITOG, half of the world "knows better" than what the manufacturer recommends.
If I have this right, we are on the "no lube, no antisieze" side of things and the rest of this doesn't matter, but there is not widespread misconception about how plugs work, and no meaningful disagreement on the orientation of an installed, torqued plug or where the electricity is likely to flow.
The meaningful misunderstanding is where, and how electrical conduction occurs in that joint. If there is not metal-to-metal contact between the threads then the presence of one or more dielectrics in the interstitial space is irrelevant. It's also irrelevant which dielectric is present outside the contact areas. Air nor dielectric grease prevents that contact.
Anti-seize works because the metallic solids are present in the contact areas. But the carrier grease is displaced from the contact.
I think that the use of anti-seize can be beneficial. I always used one until I started reading the posts about some manufacturers not recommending them. That was fine until on my old ECHO I barely got the plugs out during a change. Since then I have gotten back to using it, but I use the torque angle shown on the box rather than a torque value. This eliminates any need to correct the value on installation.
Anti-seize works because the metallic solids are present in the contact areas. But the carrier grease is displaced from the contact.
I think that the use of anti-seize can be beneficial. I always used one until I started reading the posts about some manufacturers not recommending them. That was fine until on my old ECHO I barely got the plugs out during a change. Since then I have gotten back to using it, but I use the torque angle shown on the box rather than a torque value. This eliminates any need to correct the value on installation.
I just replaced the NGK plugs on my Waverunners a couple weeks ago. They came packaged with a tiny dab of antiseize already on the threads.
WOW! That directly contradicts what NGK's policy statement shows on their website (see below).
Why is it when manufacturers have spark plug removal or breakage issues do they recommend anti seize?
The plating on NGK plugs may help but it does not prevent corrosion getting up into the threads. There are no consequences for the manufacturer when they say do not use anti seize but if the recommended it the consequences could be many.
*They have no control over the application of the product.
*OE torque specs must be reduced.
*Sloppy application could lead to cat damaging misfires, this would be a huge issue involving the vehicle manufacturer and the EPA.
Spark plugs are grounded not only at the threads but the contact area of the plug to cyl head. Dielectric grease does not interfere with current flow or grounding, many boat injectors connectors are packed with the stuff without issue.
Okay, then use anti seize, but you can’t make an argument for dielectric grease. Dielectric grease, contrary to your assertion, prevents or interferes with current flow where it touches. It is what it does.
Who's putting dielectric grease on spark plug threads? That goes on the ceramic part
It was just mentioned by one poster and got discussed because another poster said it would inhibit the ground.
Grease gets displaced once the joint is tightened. It's not preventing nor interfering with current flow because where the current is flowing is through the metal-to-metal contact where the metal is touching, not where grease exists.
Lots of imagination in regards to this. Nye lubricants used to have a great publication on electrical connections and dielectric grease which also mentioned a military study on the exact topic. Both showed that dielectric greases enhanced conduction since they lower insertion force and help to exclude moisture and other contaminates from the joint (which helps prevent corrosion). Unfortunately all their technical papers now seem to require a commercial email account registration.
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Conductivity is not a binary measurement. Some anti-seize products are dielectric. Some conduct well.
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