Anti Seize on spark plugs

[navion]

My experience with aircraft spark plugs has led me to apply the same techniques to automotive plugs with excellent results.

Piston aircraft engines usually have aluminum heads with stainless steel Helicoil style thread inserts. As the spark plugs are removed for inspection and cleaning every 100 operating hours, the threads see a lot of use. If the plugs are installed dry, there is a danger that the thread insert will adhere to the plug and come out with the plug. To prevent this a high temperature anti seize compound is used (SPARINGLY) on the plug threads.

A little anti seize will go a long way. Too much anti seize is messy and will short out the plug if allowed to get onto the electrode.

The proper way to apply the anti seize is to put a small dab onto the threads WITHOUT allowing ANY on the first full thread of the plug. I usually put a small stripe of anti seize down one side of the threads. The anti seize will distribute it's self as the plug is screwed into the head.

Remember that anti seize is CONDUCTIVE! It will short out plugs with ease if not used properly!

If any anti seize is carried into the combustion chamber, it will migrate to the plugs electrode and short it out. A plug thus contaminated is impossible to clean and is scrap at that point. Aircraft plugs run from $16.00 to over $100.00 each, and at two plugs per cylinder that can add up to some real money quickly.

Admittedly, automotive engine spark plugs don't get changed anywhere near as often as aircraft plugs. And thankfully, they don't cost a $100.00 a pop. But one seized plug or stripped spark plug hole will certainly ruin your day.

If you find that you have a seized plug, you can some times get it out by alternating loosening and tightening it as you back it out. This tends to reduce the tendency for thread galling as the plug is removed. After the plug has backed out a small amount, application of your favorite penetrating oil should be able to pass by the tapered seal and onto the threads.

[BodybyFisher]

I didn't want to admit it, but I used anti-cease on my plugs on my 91 4.9, I only used a tiny bit and allowed it to be carried around the threads by the screw in process..

[JimD]

The Guru recommended against putting anything on the plug threads that could result in a misleading - erroneous torque value. You do install spark plugs with a torque wrench, right?

[navion]

I prefer the nickel based anti seize, as it is good to about 2400 degrees. (It will still be there even if your engine melts!)

I have seen failures of copper based anti seize on some hot running aircraft engines. The nickle based anti seize is not much more expensive than copper based anti seize and a container will last a do-it-you-selfer for years, so I always use the nickel based anti seize.

If the factory specifies a torque range for spark plugs, I would always use the low end of the range. I have yet to have a plug back out when it was properly torqued. ALWAYS USE A TORQUE WRENCH!!![/b]

The only other objection that I can think that BBob would have to the use of anti seize is the fact that the heat transfer between the plug and the head would be different while using the anti seize. However, I have never found that to be a problem in an automotive application.

Britt

[BodybyFisher]

Installing the plugs with a torque wrench on the 4.9 was difficult due to the lack of space. I will definately utilize a torque wrench on the NS as the plugs are easily accessible. I am sure putting anti-cease on the plug threads is like putting a lube on the wheel lug nuts before tightening them, I once did that, and could not attain 100 ft lbs.... had to clean the threads and nuts with brake clean..

I believe its a no no to lube the head bolts before torquing also, is that correct? I think they get torqued dry..

[KHE]

The guru recommended against using anti-sieze on the spark plug threads for several reasons - It significantly lowers the torque value which can result in stripping out the threads when torquing to the factory spec. It is also conductive and if too much is used, the plug will be ruined. Also, the plug threads are plated to resist corrosion.

Most torque values in the shop manuals are for clean, dry, unlubricated fasteners.

[Ed Fenwick]

Aloha,

I didn't know that I shouldn't put any lubricant on lug nuts! I have always greased the lugs, What is the reason for not greasing the lugs?

Thanks Ed

[Scotty]

Ed, greasing or using an oil the lug nuts can disguise the actual torque reading. If the torque is suppose to be 100 ft lbs with clean and dry threads, if you use OIL or penetrant, you can torque the bolts MUCH higher than 100 ft lbs as the friction and tension is decreased. This can result in snapped studs, damaged wheels or stripped threads or even worse, warped rotors

This car look familiar, it was a beauty Ed!

[MAC]

I used anti-seize and the other day I took the four front plugs out and noticed it burned off. I used the silver colored stuff that comes in the packet. Also, I must have used too much because I had to work the plug back and forth to get it out and when I looked at the threads it had dried anti-seize lube caked in between some of the threads. So I took a small wire brush and cleaned the lube off. No more anti-seize.

[Ed Fenwick]

Wow Mike, you brought tears to my eyes. BTW I have a bunch of pix of Kilauea erupting if you want to see.

God bless Ed

[BodybyFisher]

Wow Mike, you brought tears to my eyes. BTW I have a bunch of pix of Kilauea erupting if you want to see.

God bless Ed

Ed I was watching a Discovery Channel special on Extreme Hawaii last weekend and they had Kilauea erupting amazing stuff, there was a guy there making pottery and face molds with the magma.... I would love to see photos, thanks. (I posted as Scotty by mistake, sorry) Mike

[navion]

I used anti-seize and the other day I took the four front plugs out and noticed it burned off. I used the silver colored stuff that comes in the packet. Also, I must have used too much because I had to work the plug back and forth to get it out and when I looked at the threads it had dried anti-seize lube caked in between some of the threads. So I took a small wire brush and cleaned the lube off. No more anti-seize.

Mac,

You must realize that the threaded area on all spark plugs is exposed to combustion chamber pressures and gasses. Over time these gasses work their way into the threads and condense there as combustion by products. These byproducts, over time, can cause the plug to seize in the head. Your finding of anti seize residue in the threads was perfectly normal. The spark plug threads should always be cleaned before reinstalling whether or not anti seize is to be used.

The fact that you had to work the plugs back and forth showed that they were on the verge of seizing. There is the possibility that they would have seized if anti seize had not been present.

I am curious as to why you thought that you used to much. Very little anti seize is required.

It is normal to experience some resistance when removing some spark plugs, even when anti seize has been used.

As for the "burnt off" appearance, that is normal, as the fluid that gives the anti seize it's "brushability" is sacrificial and has nothing to do with the performance of the anti seize. Anti seize, is in reality a high temperature dry lubricant.

The only real issue in using anti seize on Caddy engines is the torque question. Perhaps someone on the board with engineering connections can come up with a torque value for spark plugs using anti seize. Personally, I reduce the published dry torque by 10%, and if there is a torque "range" listed, I always use the lower figure.

Take Care,

Britt

[Spurlee]

I've used silver anti-sieze for years and years with no problem, never a siezed plug or a shorted one. A small amlunt on the mid range of the threads seems to work fine. That's interesting about it being a high temp. dry lubricant...good to know.

I especially like it for frequently changed plugs on my 2 jet ski's. They have relatively thin, aluminum heads and see a lot of inspection/changes during the season. Or on my boat motor in a high humidity environment with comparatively infrequent changes.

I just started using a torque wrench within the past year - for the prior 30 I've done everything by feel. Over time you develop a sense for tightness, but on modern stuff with much less tolerance and advanced materials I decided to upgrade my skills and toolbox.

What I noticed is how much I'd been overtightening stuff! 100lb isn't nearly as tight as I'd "normally" set a wheel lug. And spark plugs - well, let's not go there. Anyway, where I was once apparently just lucky now I'm more professional.

SP

[Ranger]

I hate to admit this but, I suspect I may not be alone so here goes. I have never torqued a spark plug. Just snugged them down good. There, I said it and now I feel better.

[jackc]

I hate to admit this but, I suspect I may not be alone so here goes. I have never torqued a spark plug. Just snugged them down good. There, I said it and now I feel better.

Whew - me too!

[BodybyFisher]

I hate to admit this but, I suspect I may not be alone so here goes. I have never torqued a spark plug. Just snugged them down good. There, I said it and now I feel better.

Ditto Man, I feel the same way, the days of the flathead 6 with no obstructions are gone and getting a torque wrench in tight locations (like on my 4.9) let alone a small 3/8 ratchet handle is nearly impossible. That said, the NS presents easier angles for torquing the plugs and IF I do my NS plugs if the angles are easy, I probably would use a torque wrench, but my plugs were done at 56,000 miles by the prior owner so they will probably outlive me....

[navion]

I hate to admit this but, I suspect I may not be alone so here goes. I have never torqued a spark plug. Just snugged them down good. There, I said it and now I feel better.

Ditto Man, I feel the same way, the days of the flathead 6 with no obstructions are gone and getting a torque wrench in tight locations (like on my 4.9) let alone a small 3/8 ratchet handle is nearly impossible. That said, the NS presents easier angles for torquing the plugs and IF I do my NS plugs if the angles are easy, I probably would use a torque wrench, but my plugs were done at 56,000 miles by the prior owner so they will probably outlive me....

My 1988 Seville was the second worst car to change the plugs in that I ever had. Three of the rear plugs had to be changed from below & over the transmission! Not much room, but definitely easier than from the top!

The absolute worst car (in my experience) was the 1969 big block Camaro with A/C! That right rear plug was IMPOSSIBLE.

Britt

[Spurlee]

There used to be, and may still be, "crush washers" on spark plugs that would flatten a bit when you tightened them down - I learned that "feel". You weren't supposed to use them twice because once flattened they weren't reusable (in theory). I still look to see if the washer is flattened...

[BodybyFisher]

There was a 440 cu in Chrysler that was near impossible to get the rear plugs out of, I was told that they used to lift the engine up to get clearance. Remember the days of removing plugs from under the generator/alternator, that first passenger side plug was a biatch.... It used to amaze me how many plugs were never changed if they were hard to get to...

[navion]

There used to be, and may still be, "crush washers" on spark plugs that would flatten a bit when you tightened them down - I learned that "feel". You weren't supposed to use them twice because once flattened they weren't reusable (in theory). I still look to see if the washer is flattened...

That disturbed an old memory cell or two! Yes, I remember when changing plugs was MUCH more common, 10 to 15 thousand miles. Torque wrenches were something that only BIG shops owned. Tighten the plug until you felt the gasket "squish" and then stop. Worked well! I never stripped a plug hole or had one back out due to under torque either. I seem to remember some bulletin stating that was an acceptable way to install plugs, but that particular memory cell has retired.

Britt

[jackc]

There was a 440 cu in Chrysler that was near impossible to get the rear plugs out of, I was told that they used to lift the engine up to get clearance. Remember the days of removing plugs from under the generator/alternator, that first passenger side plug was a biatch.... It used to amaze me how many plugs were never changed if they were hard to get to...

Hey - I've done plugs on that Chrysler. 'Bout a 74 Imperial or something. Had it up on a lift and went in through the wheel well. I was feeling pretty proud of myself until I looked on the floor and saw 7 old plugs and one shiney new one. I'm pretty sure I just let it go with the 7 plug tune-up.....

When I did my Eldo recently, I found 3 original plugs (guess where) and 5 replacements that were like R 46 TS's or something. Must have been karma.....

[BodybyFisher]

Yes it was around 1973 to 74, my neighbor used to 'let' me tune it up for him... Back then, I could make $10 doing a tune up, enough for many Philadelphia cheese steaks and chocolate shakes...

I used to use R45-S most of the time as a habit... I can honestly say, I never did a 7 plug tune up, I was a tenacious SOB, and being tall, I was able to lay in the engine compartment and just use my fingers and work with my 'feel' and a variety of wrenches/sockets. My feel isn't as good as it used to be,

[navion]

We have to remember that in the "Good Ole Daze" almost all cylinder heads were made of cast iron, unless it was something exotic, such as a Briggs & Stratton or a Maseratti!

Cast iron heads could and did withstand a lot of "spark plug torque abuse".

I have had to resort to a 3 foot breaker bar on occasion, to get some plugs out that "Joe Overtorque" installed. (Not Me! )

As for plugs that were removed with an impact wrench, they went straight into the trash! Impacting a plug usually cracks the insulator, and while it may look OK and even run good for now, that hidden crack will usually let you down when you least expect it.

I had a fellow "help" on his aircraft's annual inspection. While I was in the office, he decided to remove all 12 spark plugs from his plane's engine using an impact wrench! In doing so, he ruined every plug! At a list price of $30.34 EACH plus tax, it was a very expensive lesson for him!

Britt

[jgr7]

Speaking of the impact gun that is what the guru had said was the best way to remove the plugs in an aluminum head. bbob said, if my memory serves my that the quickness of the impact didn't let the threads gall up just got them out. No anti-sieze needed.

Jeff

[BodybyFisher]

Yes he did, it breaks the bond quick and easily..