Where do fall on spark plugs and anti seize ?

[chrisk2010]

I got locked in a debate last night with a mate of mine about anti seize and spark plugs he uses it i never have. It was the usual arguement about over torquing, trapping heat the list went on but then i got to thinking what if ..... ?

I done my Dads w202 C240 (used to be mine) last November and he hadn't changed them for a long time and they were a PITA to change all 12 of the little blighters because they had been left in so long and he does a lot of short runs in his retirement they seemed to be very tight in there.

I'm sure i'm opening a can of worms here and this has been done to death but over Christmas my ex pride and joy is due it's yearly Spa treatment and you've guessed it I'm wonerding if they are going to be just as hard this year and if they are should i risk it ?

 

[Joderest]

Hmm, spark plugs, tricky little devils.
If i were changing spark plugs on our Mini, i would start with engine warm, and gently undo the plugs, i have always used a smear of copper grease on threads putting them back in, i do not know if for anti seize, as would soon burn away with the heat, more just to make putting them back easier. I always install plugs when engine cold, nip them up, and re tighten to correct tightness when they are all in.
I have never snapped a plug yet, but always a first time !!!. I think its because these days with modern design engines, plugs are half the size they used to be, you need to be careful as they break very easy, in the old days it was fit, 2 grunt pressure and forget.
In my Daughters Aygo, they are very easy as normal size, and there are only three to do !!

 

[chrisk2010]

Cheers Joderest that pretty much the way i do it apart from the copper grease, i shouldn't really have said anti seize but seemed like a well used term. I thought maybe over the years since i have been out of macanical work something new (method or product) may have popped up.

I was always taught that it isn't needed in modern day engines unlike some of the cast lumps i used to work on in older diesel (glow plugs) and gas forklifts so i never used it.

I should mention when i owned the car i used to take them out check them clean the threads with a bit of electrical cleaner and a cloth and put them back in probably every three to four months depending on usage so never had the problem of them becoming a bit stubborn.

 

[Alps]

I have always used a smidgen of copper grease when putting plugs back in, this to stop them seizing if any moisture starts corroding, usually from condensation in the cold months

 

[190]

It's a topical argument and seizure has become more of an issue with modern cars having very long plug change intervals and some plugs now also have very long threads.

The Engineers stance is that the torque settings will be for dry threads so anti seize shouldn't be used or there is a risk of over torquing. Some plugs now claim to have an anti seize plating on the threads which would seem to support this approach.

The pragmatic argument is a very small amount of anti seize will make them easier to remove when the time comes. I fall in this camp and always use a 25% reduced torque setting to compensate. In the case of my plugs they are long thread with a recommended torque range of 10.8-14.5 lb. ft. I would use the lower figure. If someone else does them I would worry that there is a potential to over tighten them.

 

[chrisk2010]

Both votes for some copper slip then.

some plugs now also have very long threads.

This was in my mind when i recently changed the dainty but long threaded ones on my w203 c230 i didn't apply any but had my finger in the pot thinking i'll be checking them in March anyway.

 

[markjay]

Car manufacturers say that spark plugs should be fitted dry. Then replaced every 4 years to prevent seizing.

And yet... on my Vauxhall Omega, when I removed the factory-fitted GM-Branded Bosch spark plugs.... they had a nice rich layer of copper grease applied to the threads.

Go figure.

 

[markjay]

Owners forums nothing is ever lost

Spark Plugs Change 2.6/3.2 V6 (2.5/3.0 similar)

 

[chrisk2010]

Haha ! nice write up !

To quote : "Pic 18 – The old plugs removed from the engine clearly had copper grease applied to the threads, and since these were the original factory-fitted ones I followed suit with a thin smear of copper grease. However, some say that the spark plugs should be fitted dry, so make up tour own mind which is best for you. As I said, I chose the old-fashioned method and had the plug threads copper-greased."

So really it seems it's just down to personal experience and preference i've done them dry but check frequently ( i was just taught that way ) so never had a problem. My dad who's get checked far less reguarly may benefit from smidge of copper grease and being twin spark with 12 plugs i only have ten knuckles to skin so every little helps i guess. i shall be raiding the workshop.

 

[Railwayman]

Been using copper slip on sparkplugs, wheel nuts and just about every other thread on all my cars, never had a problem in 45 years.

When installing plugs the key is not to over tighten.

 

[markjay]

Been using copper slip on sparkplugs, wheel nuts and just about every other thread on all my cars, never had a problem in 45 years...

Same here.

Said that.... if I were to do this now, I would probably fit spark plugs and wheel bolts dry.

I have no scientific or logical reasoning to support this change of heart though....... sorry if this does not help

 

[chrisk2010]

It doesn't seem there is much scientific evidence either way

I never over tighten any thread it is a massive pet peave of mine i used to work with a mechanic who was a body builder and the saying went " If Dennis put it on only Dennis can flipping take it off himself" As many an oil filter were been crushed trying to remove one that Dennis put on ! We started to think he was tightening wheel bolt with a bar extention but no ... just a standard torque wrench and a 360 turn to nip up

 

[chrisk2010]

oh and sorry everyone has been a massive help as i know what'll do now

 

[190]

Even if we haven't reached a scientific conclusion there is one definitive piece of advice and that is the recommended torque value needs to be reduced where anti seize is used because it acts as a lubricant. Of course then we can argue about how much it should be reduced. 20- 25% is usually specified.