Author Topic: Spark plug dilema  (Read 1133 times)

culzean

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Re: Spark plug dilema
« Reply #15 on: December 30, 2017, 11:47:12 AM »

Graphite paste is also ideal but doesn't seem to be in vogue these days. Not sure why though.

Mostly because Molybdenum disulphide and Tungsten disulphide have replaced it as a solid lubricant.  Graphite is more of a lubricant than an anti-seize compound like copper.
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

MartinJG

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Re: Spark plug dilema
« Reply #16 on: December 30, 2017, 01:56:35 PM »

Mostly because Molybdenum disulphide and Tungsten disulphide have replaced it as a solid lubricant.  Graphite is more of a lubricant than an anti-seize compound like copper.

Thanks for that snippet of info. Interesting. Most of us know about 'sticky' alloy wheels. That explains the reasoning behind the use of copper.
« Last Edit: December 30, 2017, 05:45:28 PM by MartinJG »

Denbo

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Re: Spark plug dilema
« Reply #17 on: December 30, 2017, 09:00:31 PM »
I learn something new every time thanks.

The eight NGK plugs I bought from e-bay, (just under 16 quid), are actually made in France, although I thought they would be Japanese. I just checked one of them there and the gap is as you say Culzean, 1.1mm, so that's one less thing to concern myself about.

Would you know if I could use my many years old, Retinax A grease, which I believe, is high melting point or would I be better purchasing the copper grease you mention?

Many thanks again all for your advice.

culzean

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Re: Spark plug dilema
« Reply #18 on: December 30, 2017, 09:40:15 PM »

Would you know if I could use my many years old, Retinax A grease, which I believe, is high melting point or would I be better purchasing the copper grease you mention?

Many thanks again all for your advice.

The whole idea of copper grease is that copper will stay behind when grease part is long gone.  The copper is to stop the aluminium and steel seizing up and makes the plugs easier to remove next time. Also copper is a good conductor of electricity for the spark, where normal grease is an insulator.

Normal grease is a lubricant - copper grease is an anti-seize compound not a lubricant,  and vaseline is a medical substance  (except you can use it on battery and electrical terminals to prevent corrosion by sealing water out - it has a very low film strength so will squeeze out of the way when clamp is tightened to allow metal  to touch).
« Last Edit: December 31, 2017, 11:01:58 AM by culzean »
Some people will only consider you an expert if they agree with your point of view or advice,  when you give them advice they don't like they consider you an idiot

Denbo

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Re: Spark plug dilema
« Reply #19 on: December 31, 2017, 02:30:51 PM »
Thanks again Culzean, for that much needed info.
I will get the copper grease you mention.

Have a great new year all.

sparky Paul

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Re: Spark plug dilema
« Reply #20 on: December 31, 2017, 09:23:20 PM »
Personally, I never grease spark plug threads - if you change them at the right intervals, it should never be a problem. Most modern plugs come with a hard anti-sieze coating applied, including NGK.

If you use a torque wrench to do the final tightening, you must avoid any wet anti-sieze compound as this can act as a lubricant and affect torque readings by up to 25%, and you certainly don't want to be over-torquing into an aluminium head.

culzean

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Re: Spark plug dilema
« Reply #21 on: January 01, 2018, 08:39:32 AM »
Personally, I never grease spark plug threads - if you change them at the right intervals, it should never be a problem. Most modern plugs come with a hard anti-sieze coating applied, including NGK.

If you use a torque wrench to do the final tightening, you must avoid any wet anti-sieze compound as this can act as a lubricant and affect torque readings by up to 25%, and you certainly don't want to be over-torquing into an aluminium head.

I never use torque wrench on spark plugs,  just follow the 'hand tight + 1/2 to 2/3 turn' rule to partially squash the sealing ring (or 1/4 turn for pre-used plugs, but I never use plugs again anyway).  NGK describe the yellowy coating on their standard life plugs as a 'zinc-chromate shell coating' which apparently is designed to act like a shell and break away from the plug thread when unscrewing plugs to prevent damage to thread in cylinder head if the outer layer has bonded, but do not say where the material that is broken away goes ? does it fall into cylinder or remain in thread to make next plug tighter to screw in and out ?  I still use a smear of copper grease on standard plugs (dull yellow silvery coating) because I have had a problem getting some 'original OEM factory fitted' standard life plugs out of alloy heads but never subsequently had a problem after I used a light smear of copper grease. 

These days I only use iridium or platinum plugs anyway, which have a smooth tri-valent nickel (like shiny chrome) plating and because these plugs are designed to be left in for 60,000 to 100,000 miles this coating is designed to not bond with anything and release smoothy,  and it seems to work, I guess the reason they don't use it on all plugs is due to extra cost. 

I know torque values are for dry threads and lube means you have to reduce torque by 20% (this is standard throughout engineering) but the plating on threads can affect torque as well depending on whether it is a fairly rough 'zinc-chromate' or a smooth 'trivalent-nickel' and also depending what sort of state thread in cylinder head is in (is it bunged up with previous 'shell' coating zinc chromate material from previous plug changes LOL)   
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JazzyB

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Re: Spark plug dilema
« Reply #22 on: January 01, 2018, 10:27:27 AM »
i use just a drop of copper grease on plugs and torque them up, never had a problem in various cars in over 40 years!

sparky Paul

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Re: Spark plug dilema
« Reply #23 on: January 01, 2018, 12:56:11 PM »
NGK describe the yellowy coating on their standard life plugs as a 'zinc-chromate shell coating' which apparently is designed to act like a shell and break away from the plug thread when unscrewing plugs to prevent damage to thread in cylinder head if the outer layer has bonded, but do not say where the material that is broken away goes ? does it fall into cylinder or remain in thread to make next plug tighter to screw in and out ?

Adding copper grease doesn't take the zinc chromate coating away, it's still there whether you add grease or not. In any case, the coating is only the thinnest coating of dust. Incidentally, the copper flakes in copper grease most definitely does adhere and can become compacted in the thread roots with repeated use.

I'm a big fan of Copaslip and its equivalents, I've used copious quantities of the stuff over 30+ years at work in harsh conditions. I still use plenty on cars, particularly on captive threads and threads into castings, but I don't use it on spark plugs, as the thread is open to the heat of the combustion chamber, but sealed from the outside. If you put anything wet on the plug threads, it will dry out from the heat of combustion and some of it will invariably migrate into the cylinder bore.

I don't was this to turn into a debate on what's right or wrong, if greasing spark plugs works for you, that's great. My personal opinion is that there are drawbacks, and that it is unnecessary with modern plugs if you change them at the recommended intervals. NGK also recommend that you insert plugs dry, without any additional lubricant or anti-seize compound.
« Last Edit: January 01, 2018, 12:59:02 PM by sparky Paul »

Jocko

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Re: Spark plug dilema
« Reply #24 on: January 01, 2018, 01:17:18 PM »
I have been changing spark plugs for 50 years. Both iron and alloy heads/blocks. Never used any lubricant and never had any problems removing them.

Denbo

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Re: Spark plug dilema
« Reply #25 on: January 09, 2018, 09:56:30 PM »
Just to end the thread I started, I finally replaced the 8 plugs last night, taking about two and a half hours. I wanted to take my time and did each plug seperately before going on to the next. The four at the back were certainly more awkward but doable. I bought the Carlube copper grease which made the new plugs screw in much easier.. Thanks Culzean for that tip. I used it sparingly and should have enough in the tube to change the plugs a few more hundred times!

I am not altogether certain if the plugs needed changing. The four back ones looked to be in the same condition as the four front ones, all of them having that healthy dry brown deposit on them. I can tell you that when I 'guaged' them, it took an 80+40 in the gap, compared to an 80+20 on the new ones!

My daughter told me today that she thought it was driving really well and seemed to have more "oomph", as she described it.

As an aside, I noticed that the front plate on the Jazz, states that it is assembled in China, but as someone else mentioned on this site, Honda would have high quality control in whatever country it is made.  I know that everything works well on this motor. I even tried the air-conditioning on my test drive after the plug change. While slightly noisy, it seemed to work but was hard to judge, due to the present cold climate. I will try again once the warm weather returns.

Anyway, folks thanks again for all your valued input. It gave me great peace of mind to carry out the spark plug operation.

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