Anti-seize on spark plug threads

Domenick

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Domenick
In the aviation world we are taught to always use anti-seize on our spark plugs. I always have and I torque to the recommended value.

Not so in the automotive world.It seems the consensus there is DO NOT use anti-seize on spark plugs. Apparently, new automotive plugs are coated with an anti-seize plating.

https://www.driven2automotive.com/b...se-copper-grease-when-installing-spark-plugs/
https://www.motor.com/magazine-summary/trouble-shooter-dec-2012/
https://ricksfreeautorepairadvice.com/anti-seize-spark-plug-threads/

Should we, in the aviation world, continue to use anti-seize? Are the threads of Tempest and Champion aviation spark plugs "trivalent plated"?
 
Things to do with Spark Plugs.
clean the old antiseize out the threads prior to adding new. (both cylinder and plug) flip the gasket over when the plug is installed.
And always use a torque wrench. (25 ' Lbs)
 
In the aviation world we are taught to always use anti-seize on our spark plugs. I always have and I torque to the recommended value.

Not so in the automotive world.It seems the consensus there is DO NOT use anti-seize on spark plugs. Apparently, new automotive plugs are coated with an anti-seize plating.

https://www.driven2automotive.com/b...se-copper-grease-when-installing-spark-plugs/
https://www.motor.com/magazine-summary/trouble-shooter-dec-2012/
https://ricksfreeautorepairadvice.com/anti-seize-spark-plug-threads/

Should we, in the aviation world, continue to use anti-seize? Are the threads of Tempest and Champion aviation spark plugs "trivalent plated"?
Remember auto plugs are usually just replaced around 100,000 miles while aircraft plugs removed and replaced for compression checks every year or 100 hours. No plating on mine.
.
 
Remember auto plugs are usually just replaced around 100,000 miles while aircraft plugs removed and replaced for compression checks every year or 100 hours. No plating on mine.
.
This varies greatly, depending how many times the plugs are blasted, usually about 500 hours the gaps will widen to a point you need to replace them. I have seen the engine get to 1000 hours, but that is seldom.
 
If you have a Lycoming the instructions are quite specific. Service Instruction No. 1042AH, page 2, "Spark Plug Installation Guidelines", item #3.
When I asked a Lycoming rep which specific copper based compound anti-seize compound, he said the Lycoming factory uses only Loctite C5-A.

https://www.lycoming.com/sites/default/files/SI1042AH Approved Spark Plugs.pdf



ab467.jpg
 
Things to do with Spark Plugs.
clean the old antiseize out the threads prior to adding new. (both cylinder and plug) flip the gasket over when the plug is installed.
And always use a torque wrench. (25 ' Lbs)
You don’t have an inch-pound torque wrench? Lol :confused:
 
Why do you suppose there is a difference? Hint: it ain’t just math.
So what is it, then? Are you telling us that 300 inch-pounds isn't the same as 25 foot-pounds? Is this the "new math" kids are getting these days?
 
So what is it, then? Are you telling us that 300 inch-pounds isn't the same as 25 foot-pounds? Is this the "new math" kids are getting these days?
what about 330 in-lbs? Do you think the ft-lb wrench is that accurate? And what's the difference between the wet and dry torque values? With anti-seize it'd be wet right?
 
So what is it, then? Are you telling us that 300 inch-pounds isn't the same as 25 foot-pounds? Is this the "new math" kids are getting these days?

The hinted-at message was kind of cryptic, but I'm guessing that the point may have been that a torque wrench with inch-pounds indications rather than foot-pounds, generally, is designed to be used for applications where lower, more precise torque values are specified, and that a beefy foot-pound wrench might not be as precise/reliable at the lower end of the scale?
 
It's funny, some worry about a couple foot pounds of torque, when I'll wager that 90% of the torque wrenches never get calibrated.

or worry about the quality of the tools they use.

Yet there are those who are that anal retentive :)
 
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If you have a Lycoming the instructions are quite specific. Service Instruction No. 1042AH, page 2, "Spark Plug Installation Guidelines", item #3.
When I asked a Lycoming rep which specific copper based compound anti-seize compound, he said the Lycoming factory uses only Loctite C5-A.

https://www.lycoming.com/sites/default/files/SI1042AH Approved Spark Plugs.pdf



ab467.jpg

My Lycoming manual says to apply C5-A copper-based anti seize or engine oil to the threads of each spark plug. I use anti-seize but I believe mine is by Permatex.
 
what about 330 in-lbs? Do you think the ft-lb wrench is that accurate? And what's the difference between the wet and dry torque values? With anti-seize it'd be wet right?
Torques specified for sparkplugs by Continental and Lycoming will be based on the presence of the anti-seize they specify.

Torque wrenches are to be calibrated annually. Shops need to have them done as often as it takes to keep them accurate. If a shop uses a particular wrench several times a day, it needs calibrating a lot more often. If it gets dropped it needs recalibrating. Calibration is done using equipment calibrated and traceable to a national standard and done by trained technicians. The wrench is internally adjusted to get it as close as possible between 20% and 100% of its torque range, then a chart is made as the wrench is tested at various settings and the actual test numbers are recorded in both left- and right-hand directions. A wrench that can't give the same torque on every try is rejected. Cheap wrenches are like that. So the mechanic looks at the chart and figures whether he needs to adjust his wrench up or down a bit to keep the torque within the specified range for that particular fastener.

330 inch-pounds is just 27.5 foot-pounds. I didn't even need the calculator for that. If my wrench's calibration chart shows that it's torquing one foot-pound low at that setting, I just set it to 28.5. This isn't rocket science. And for the majority of fasteners, a range is given that makes the adjustment moot.

https://www.faasafety.gov/files/notices/2010/Apr/10-01[1].pdf
 
It's funny, some worry about a couple foot pounds of torque, when I'll wager that 90% of the torque wrenches never get calibrated.

or worry about the quality of the tools they use.

Yet there are those who are that anal retentive :)
probably right....lol ;)
 
Torques specified for sparkplugs by Continental and Lycoming will be based on the presence of the anti-seize they specify.
YGTBSM, do you really think it makes a difference ?
 
YGTBSM, do you really think it makes a difference ?
Yup. The argument was over DRY or lubricated threads. Do you thing the manufacturers are going to publish a torque spec for dry sparkplug threads, when they've specified anti-seize on them?
 
Yup. The argument was over DRY or lubricated threads. Do you thing the manufacturers are going to publish a torque spec for dry sparkplug threads, when they've specified anti-seize on them?
The point is, does it make any difference which product is used.
nickel has a higher temp, thus better protection .

I'll bet you can't measure the torque different between the products two.
 
The point is, does it make any difference which product is used.
nickel has a higher temp, thus better protection .

I'll bet you can't measure the torque different between the products two.
I'll still use copper if that's what the manufacturer says to use.
 
Many years ago I worked as a tech at a place that made products that we occasionally installed on submersibles and sometimes on Navy submarines. Everything had to be certified as being "sub safe" and we still didn't have the kind of discussion about foot vs inch pounds or calibration timelines, inspection procedures, regulation adherence, etc. as we see here on POA. I love this place but DAMN!
 
Many years ago I worked as a tech at a place that made products that we occasionally installed on submersibles and sometimes on Navy submarines. Everything had to be certified as being "sub safe" and we still didn't have the kind of discussion about foot vs inch pounds or calibration timelines, inspection procedures, regulation adherence, etc. as we see here on POA. I love this place but DAMN!
We don't make the rules.
 
We don't make the rules.

I get it but here is my theory.

When the rules are written in black and white, I follow them. As an electrical engineering student there were times I was expected to understand the rules and make things happen withing the rules set forth by physics, electrical theory or policy. In the Army I was given a set of rules and told to complete my mission (lead tank commander or scout gun truck commander) within those rules but everything else was up to me.

Is that not how this works? Task A must be completed within standard 1.2, task B must be completed within standard 2.7... As long as you meet or exceed that standard.... who cares?
 
Things to do with Spark Plugs.
clean the old antiseize out the threads prior to adding new. (both cylinder and plug) flip the gasket over when the plug is installed.
And always use a torque wrench. (25 ' Lbs)

Lycoming specifies 35 ft-lb.
 
This varies greatly, depending how many times the plugs are blasted, usually about 500 hours the gaps will widen to a point you need to replace them. I have seen the engine get to 1000 hours, but that is seldom.
Unless you use fines. My Autolite fines never need re-gaping since point erosion at 1300 hours is nil. I just pickout the junk with a dental pick. And they cost less over time.
 
Suppose plugs were just tightened snug by feel. What terrible thing is supposed to happen?
Not too long ago I had a 1992 Nissan 240SX. I changed out the spark plugs and did not torque them. This was before I owned an airplane and a proper torque wrench--I did have a torsion bar torque wrench.

I started the car in the underground parking garage of where I was working. I heard a rhythmic psst-psst-psst, and while I was wondering WTF ... BANG! A pimple appeared in the hood. The engine starting shaking and shimmying like a twerking female popstar, and I shut her down. Popping the newly customized hood I found one of the spark plugs, laying loose, plug wire still attached, laying atop the engine.

It took a heli-coil to repair the damage.
 
Not too long ago I had a 1992 Nissan 240SX. I changed out the spark plugs and did not torque them...

Did you simply forget to torque them, or did you not know you were supposed to torque them?
 
I get it but here is my theory.

When the rules are written in black and white, I follow them. As an electrical engineering student there were times I was expected to understand the rules and make things happen withing the rules set forth by physics, electrical theory or policy. In the Army I was given a set of rules and told to complete my mission (lead tank commander or scout gun truck commander) within those rules but everything else was up to me.

Is that not how this works? Task A must be completed within standard 1.2, task B must be completed within standard 2.7... As long as you meet or exceed that standard.... who cares?
Much of the argument here arise between pilot/owners who want to know stuff, and mechanics who do know the stuff. Some owners will dispute the aviation standard practices. Some mechanics will disagree with each other over stuff they've "always done that way." Some mechanics will keep using procedures that were obsoleted a long time ago by service bulletins, service letters or maintenance manual revisions. Some owners will insist that their way is the right way because they do it that way on their cars.

There is latitude in a lot of things. Some guys tighten sparkplugs for 40 years without a torque wrench and get away with it, while others will do that and overtorque the plugs repeatedly until the threads tear out of the head. Rare, but it happens. Sparkplug threads are big and somewhat forgiving. If they tighten 1/4" bolts and nuts without a wrench, overtorquing is far more likely, and bolts break. I've seen stretched and broken AN4 bolts on brake calipers. Had to very carefully remove a broken AN4 bolt out of the retract actuators in a 182RG. The threaded end was broken off below flush in the airframe casting, and if I couldn't get it out, half the airplane would have had to come apart to get that casting out. The airframe is built around it.

When it comes right down to it, a lot of pilots and owners just don't know how much there is to know when a mechanic studies and apprenctices for his ticket. It's like this:

upload_2020-10-10_9-50-34.png

I got my PPL in a few hours of study and flight, totalling maybe 100 hours. It took me a bit longer to get the commercial. The IFR and Instructor ratings took a while, too. Altogether there was less than maybe 15 months work. My Aircraft Maintenance Engineer ticket (Canadian A&P-IA) took me four years (7200 hours minimum) of apprenticeship and the equivalent of two years of study. A student pilot in Canada can solo at 14 years of age, hold the PPL at 17, Commercial at 18, but that AME ticket only goes to someone 21 or older. All that says something about the time it takes to acquire the skills and knowledge to be a mechanic.

Aviation is rewarding but terribly unforgiving. There is no place for flippancy in it, whether in flying or maintaining. It will kill you.
 
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