Spark Plug

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Apr 3, 2005 | 07:18 PM

sridhar

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Spark Plug

I was just taking a glance at the tech section at Audipages, and I noticed it said that anti-seize shouldn't be used on plugs. Why not? The reason why I ask is that the last time I did the plugs, I used anti-seize. Is it ok, or should I bother cleaning the anti-seize out of the threads?

(I put in Denso Iridiums. Big improvement.)

Peace... Sridhar

Apr 3, 2005 | 08:25 PM

garibaldi

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Re: Spark Plug

ive read that before in many later model manufacturer tech bulletins, and honestly, i dont know why they advise against it, perhaps something to do with getting a good ground to the head???? maybe the manufacturers are applying their own form of anticorrosion agent to the threads (They still look like plain old plated steel bodieid plugs to me) who knows, I ve worked on and built motors for the past 10 years, and will alway use antiseize on the threads, not too much of it, but look at it this way, whatever technology they may have uncovered, still does not deny the fact that basic meatllurgy and chemistry applies. Two dissimilar metals, harsh environment, etc, and that usually leads to some sort of galvanic reaction. So, couple that with todays high performance ignitions, high performance plugs, which lead to extended maintenance intervals (ie, plug changes at 50k, or 100k) makes me wonder how nice it is going to be to try and remove a 5plus year old spark plug from an aluminum head when its basically seized in there. I mean, helicoils are a great invention, but I dont like doing them in place in a cramped enige bay on a high end car. and its not like you can go doen to NAPA and buy a spare head for an A8 or any car for that matter if you ruin the threads. Some may disagree, but I would and do use the antiseize on threads.

Apr 3, 2005 | 11:13 PM

ryoung

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One caveat ...

I've also always lubricated spark plugs in aluminum heads. I would just use a few drops of oil from the dipstick (Mobil 1 of course), but anti-sieze is probably a better idea.

One caution: With lubricated threads, friction has been dramatically reduced, and the spark plug's "dry" torque specs are now much too high. I would just tighten by feel, but you need to be careful to avoid over-tightening.

Apr 4, 2005 | 03:19 AM

JimR

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Re: "makes me wonder how nice it is going to be to try and remove a 5plus year old spark plug"

Answer: Not very.

<img src="http://pictureposter.audiworld.com/1018/plug_shear_1.jpg"><ul><li><a href="https://forums.audiworld.com/a8/msgs/24844.phtml">Full story here.</a></li></ul>

Apr 4, 2005 | 04:03 AM

matrixabc

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I do not use any Anti-size compound

I make sure I clean the thread in the head, oil will burn at the tempratures the plug will see and eventually seal it in!.
Also the plug needs good conductivity between the thread and the head to function well an anti size compound could build up and act as an insulator.
I have been replacing spark pluges for many years and as long as the thread in the head is clean it shouldent bind when removing, there in no chance of oxidisation , and with the temp going from ambient to 300 deg C it will be constantaly contracting and exspanding also helping to prevent siezing....

Apr 4, 2005 | 06:33 AM

barryl

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Re: Spark Plug

Hello,

If you use too much antiseize it will destroy the Oxygen sensor. I always use a little on the threads. You only need a tiny bit.

Barry

Apr 7, 2005 | 12:43 PM

-OvO-

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Horror Story

Once upon a time, my dad gave me his 12-year-old Oldsmobile station wagon. I drove it for a couple of years, no major complaints. One wet day it refused to start. Good spark at the plug wires, good fuel, no reason to suspect the compression was suddenly worse than yesterday, and it sounded like there should have been plenty of compression at least to start the thing. So I decided to pull the plugs and see if I was getting spark at the plug.

The first plug was badly worn. The second plug... Well. I had never seen a plug fail in quite this fashion.

The threaded shell split off from the body of the plug when I put the socket wrench on it. So the plug body dropped into the cylinder, and the threads stayed welded to the head.

Instantly turning a 20-minute job into a three-day one, and turning the station wagon from an around-town kid and crud hauler into a piece of scrap.

Now I use anti-seize.