Here is a high voltage circuit breaker that’s filled with dielectric oil, must be voodoo magic for it to conduct electricity.
anti seize on spark plugs
- Thread starter The motor guy
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When the contacts are closed, the voltage is high enough and the film is thin enough that it arks and evaporates the oil between the contacts almost instantly, so once closed there is no oil between the contacts. The key to them working is high voltage so it can overcome the little bit of insulation the thin film provides, and its also why these large grid switches need to be serviced once in a while.
Its possible the same happens on the threads - you are talking about 20KV+ at the bottom of the coil? It makes more sense than a few ft lbs of torque compressing all the grease out actually, now that I think about it for a minute.
Nope, see the shape the tips of the contacts have? Oil films is only effective on large and flat areas. Otherwise it gets squeezed out quickly and only fills in the microscopic valleys on the metal surface.When the contacts are closed, the voltage is high enough and the film is thin enough that it arks and evaporates the oil between the contacts almost instantly, so once closed there is no oil between the contacts. The key to them working is high voltage so it can overcome the little bit of insulation the thin film provides, and its also why these large grid switches need to be serviced once in a while.
Its possible the same happens on the threads - you are talking about 20KV+ at the bottom of the coil? It makes more sense than a few ft lbs of torque compressing all the grease out actually, now that I think about it for a minute.
That’s the same with a threaded area. Small surface area and quite large loads on it, therefore there will not be any oil film on the peaks.
Also, the voltage doesn’t go though the threads, it’s just the ground, so no sparks there to evaporate the lubricant.
Another point about the threads, it’s an interference fit. Meaning the two surfaces grind against each other when torqued. No lubricant will stay in there since there is clearance for it to migrate to.
I disagree. Shape, etc doesn't matter. If one side is hot at high voltage there is going to be an arc long before they are fully closed. Post me a link to a real one?
There are two types of oil filled circuit breakers, one like you posted where everything is submerged, and a type where there is only oil around the contacts.
There is no voltage going through the spark threads, therefore no sparks. Not sure where you’re getting your theories from.
Umm, how do you think current flows - it just goes to nowhere? And your making fun of my knowledge?
It needs a path, which is why the ground side of the electrode is physically connected to the threads. Ever try to get a plug to fire without grounding the threads? Hint - it doesn't
I said there is 20KV at the bottom of the coil. That voltage travels down the plug, jumps the gap, which is a resistor that drops the voltage - and the current flows back up the electrode which is mated to the threads. I have no idea how much the voltage is after it jumps the gap. Could be tiny, could be a lot. I have never seen that number published anywhere.
From NYE lubricants.
once the spark jumps the gap, the remaining voltage is minimal, certainly not enough to spark at the threads and evaporate the lubricant, which is what you’re suggesting with zero evidence for it.
I speculated - and was very clear I was speculating. At least I know how a spark plug works. Can you quantify "minimal" voltage - I am curios to know now?
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If I have difficulty in removing the originals then I would apply a thin layer on subsequent plug swaps, if no difficulty then no anti -sieze.
The threads and seat provide a ground connection. Without it , the spark won't jump the gap.
I've always used Febi 26712 ceramic grease. I believe it was specifically designed for glowplugs. I use a pea sized amount on my finger and smear it as thinly as I can over the threaded section of the plug.
I changed the glowplugs in the Defender last year for the first time in 8 years and they literally just fell out and the grease still looked fresh.
I changed the glowplugs in the Defender last year for the first time in 8 years and they literally just fell out and the grease still looked fresh.
I sure have.
When I replaced the plugs on the V70R - they were stuck. Really stuck.
I had to work them back and forth. Even shot a bit of Kroil in there, which helped a lot.
How did they get so stuck? The previous “mechanic” slathered them in anti seize. So much silver gunk that it piled up and made the plugs hard to turn. Hard, dried out silver grit, with more silver piled on top.
I chased the threads, several times, to get all the excess anti-seize out.
The new plugs went in with a thin dab of copper antiseize.
I’m not opposed to antiseize, but it has to be done correctly, or it’s worse than nothing.
Here is the issue - voltage is related to resistance.
So, the current flows though the metal contact points, with basically no resistance.
No resistance, means no voltage across that connection.
V=I*R. Since R=0 (no resistance) V must also be zero, no matter big I (current in amps) might be.
Big resistance across the plug gap, so, R is big there, which means that V is big there. I.E. it takes a lot of voltage there to get current to flow.
Which is often the problem in many discussions on here.
We’re talking micro volts. Pretty much nothing. All the voltage is discharged by jumping the gap.
absolutely correct. I had great difficulty R&R plugs recently that had AZ on threads. Took awhile working back and forth and solvent application. Learned my lesson. No AZ or just a tiny bit. Been doing AZ for years wo problems <shrug>
Yes, that makes sense. Thank you.
Can you explain that. Before the arc there is no circuit. It takes a high voltage to arc, but once the arc is complete the ionizing of the A/F cause resistance and voltage drop near instantly - is my understanding? The explanation above makes more sense.
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