How To: Change Your Spark Plugs (valid for most cars prior to coil-on-plug systems)

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How To: Change Your Spark Plugs (valid for most cars prior to coil-on-plug systems)

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It seems so basic, yet here is a pictorial step by step guide to properly changing out your spark plugs (Ferrari 348 used as demonstrator), including one step that I'll bet most people haven't heard about (or have been taught incorrectly).

Here's what you'll need:

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new spark plugs (8 for the 348)
Spark plug socket (18mm for NGK and Splitfire)
Socket extension
Ratchet (flex handle preferred)
Feeler gauge (to gap old-style plugs, but not for Iridium of any brand, Bosch+4, or Splitfire plugs)
dielectric grease
anti-seize compound
Clean rag (disposable)
shop gloves
long nose pliers (in case your spark plug socket has trouble removing a plug from your block after it's been unscrewed)
Stabilant 22a (RicambiAmerica.com), Marine Corrosion Block (West Marine), or other suitable electrical contact enhancer
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With your engine off and cold (not hot!), pop your engine bonnet and wipe-off or blow off any surface dirt on around your spark plug boots.

You are now going to begin a repeating process of removing and then replacing one spark plug at a time. By doing one at a time, you won't risk connecting plug wires in the wrong order. Minimizing risk is a nice thing.

 

THE CYCLE

With gloves on, grasp the underside of the rubber boot as shown
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Twist it 1/4 turn clockwise, then counter-clockwise to "break" it from where it has been sitting on your spark plug, then twist it in either direction as you lift up on the boot so as to remove the plug wire from the spark plug.

Always apply force to the boot on the end of the plug wire, never on the wire itself.

With the plug wire removed, apply Stabilant 22a to the metal contact areas inside the rubber boot of the spark plug wire, then let the plug wire dangle...leaving open a path to its spark plug.

With your spark plug socket attached to its extension and mounted to your ratchet, insert your socket into the block path so that it locks onto the base of the spark plug (hint: turn it a bit clockwise/counterclockwise to feel the socket grip against the spark plug).

Set your ratchet to loosen, and apply counter-clockwise pressure to unbolt/unscrew your spark plug.

Pull your sparkplug out with your attached spark plug socket (if your socket fails to adequately grip your spark plug, just insert your long-nose pliers and grab the now-unscrewed spark plug by its metal cap end to remove) as shown:
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Line up each used spark plug sequentially (labeling/numbering is a good idea) so that you can later photograph and analyze your engine's condition based on the debris/wear on each plug. These should be out of the way.

 

Pick up a new spark plug, and if it a type that should be gapped (e.g. Champion), then measure its gap by inserting your feeler gauge between the plug's ground and electrode, rotating the gauge until it "sticks" or touches at both the top and bottom.

Ferrari 348 plug gaps should be .028 inches wide, as shown:
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If the gap needs to be adjusted, grasp its curved ground from behind or above with your long nose pliers and bend in the appropriate direction to widen or shrink the gap to the desired distance. Do *not* insert a feeler gauge or flatblade screwdriver under the ground. Do *not* use the center electrode as leverage to change the gap distance. This can do unseen damage to the plug, including knocking platinum/iridium off of the electrode or even breaking the plug physically. Touch only the curved ground, not the central electrode.

 

Once the spark plug is confirmed to be correctly gapped, unscrew the metal end cap and apply Stabilant 22a to the internal threads as shown:
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After applying Stabilant 22a or Corrosion Block, screw the metal cap back on hand tight.

Put a small amount of anti-seize compound onto the middle third of the new spark plug's threads (leave 1/3 of the threads near the electrode uncoated, leave 1/3 of the threads near the ceramic base uncoated) as shown:
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good thread. nice photos. i had a horrifying experience yesterday. pulled a plug to see what was going on in there. it looked perfect. i was happy. putting the plug back in i use a socket with a rubber insert that holds the plug while starting it in the hole. well i screwed the plug in by hand until it started getting tight then went to the rachet which got tight then suddenly loose then kept spinning. i freaked! oh no... stripped the plug hole. stomach lurched, cold sweat, disbelief. after a second to recouped my composure i realized the rubber insert had stopped the socket from engageing the nut on the plug. whew, all's well that ends well.

 

Here's a bit about High Voltage (great AC/DC reference, by the way). High voltage wires leak.
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To stop some of the leakage from high voltage wires, there is a great solution called a "dielectric."

A dielectric is what is used in between metal plates in capacitors...it won't conduct electricity very well until a severe level is reached (at which point electricity jumps through it or over it).

Anyway, the point is that something called a "dielectric" doesn't ordinarily conduct electricity very well.

Some clever folks have also combined several properties such as being "dielectric" and being a lubricant and being a water repellent.

 

So what we want to do is take advantage of the clever minds at Loctite et al.

We want to apply dielectric grease onto the **CERAMIC** of our new spark plug.
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The moral of the story is that you do not want dielectric grease on any of your metal conducting surfaces.

Here's Loctite's story: http://tds.loctite.com/tds5/docs/DIEG-EN.pdf

Because dielectrics don't conduct very well...they add resistance to metal if they are applied in between metal surfaces...reducing spark.

But if you correctly put dielectric grease only on the ceramic base of your new spark plug, you'll prevent some high voltage leakage that will give you **MORE** spark voltage/power.

Plus, the grease will keep out moisture from humidity and washes, reducing rust, etc.




And this is likely very different from what you've ever heard about dielectric grease. I've even got one brand of dielectric grease that says on its own package the opposite of the above, so some pros aren't immune to misinformation.

 

With your new spark plug now gapped, anti-seized, and coated on its ceramic base with dielectric grease, place it into the plug socket and insert it back into the engine block to replace the old spark plug.

But...remove your ratchet from the socket and extension such that you can hand-tighten your new spark plug into the block.

Once hand-tight, set your ratchet to tighten and apply pressure for 1/4 turn. Do not use so much pressure that you "GRUNT" while installing your plug! Don't overtighten.

Remove your socket and press-fit your spark plug wire boot back on.

END OF CYCLE

Repeat the above cycle for each spark plug in your engine.

 

Optional New Cycle

If desired, pull off one plug wire boot from one coil. Coat the internal metal contacts (of coil and plug wire) with Stabilant 22a, apply the tiniest bit of dielectric grease to the rubber of the boot, and reconnect the plug wire back onto the coil.

End of Optional New Cycle

Repeat the above for each additional plug wire/coil conection.



Put up all tools (count them to be sure!).

Close engine bonnet. Start engine. Verify good operation.

Now drive!
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To read your old spark plugs: http://www.ferrarichat.com/forum/showthread.php?t=121401

 

nice thread. Though I never considered it as important to use any compounds, etc. please allow me to add one warning.
You never mentioned what kind of anti-seize compound you use and the color of the compound package ( like copper ?) makes me think.

Never use COPPER based anti-seize compound on steel - aluminium joints. It makes things worse. If at all on plugs in aluminium heads use a small amount of graphite grease ( this is, what Bosch recommends ), if you want to go further, use ceramic based anti-seize compound. Or use nothing. The latter is still better than copper based compounds.

Some time ago I used some copper anti-seize compound on the wheel hubs, where they center the aluminium rim. One year, some car washes and rain drives later I had a severely hard time taking off the wheels.
And I have seen Alfa Romeo aluminium heads where plugs have been installed with copper compound what ended in a necessary helicoil repair of the plug threads.

Reason for all this is the big voltage potential between the two metals aluminium and copper, what accelerates corrosion.
Copper paste may be a good choice for plugs in iron heads but - and the manufacturers don't mention it - never in aluminium and similar alloys.

Best Regards from Germany

Martin

 

In the controversial part above, what you are doing with the silicon dielectric grease is making a watertight seal between the ceramic base of the spark plug and the rubber boot of the spark plug wire.

That keeps out moisture, preventing corrosion/rust on your spark plugs and wires.

And, since that grease is also a dielectric, your watertight seal (above) also keeps *in* electricity that would otherwise leak out (into the air or jumping to your nicely grounded engine block) of your spark plug wire connections as high voltage likes to do.


So you keep water out, and keep extra voltage/current in...all by putting a little dielectric grease onto the ceramic of the spark plug.

 

Nice tip!

You are so right, Martin. Good job. I hadn't even thought about copper.



(I used petroleum-based anti-seize compound in the example for this thread, is that OK for aluminum blocks?)

 

it's fairly unimportant, what kind of oil base is used. Important is, that there is no metal component in the compound which is so far away from aluminium in the galvanic series ( like copper ). This is the reason, why on many ceramic based anti-seize products the manufacturers underlines ' metal - free '. Or there are also aluminium based anti-seize compounds out there.
The good thing is, that one can identify with the help of the color of the substance, what it is. Most ceramic stuff is white, aluminium silvery, and copper is just copper colored.

Best Regards from Germany

Martin

 

When I change spark plugs in any car, including my F-car, I use a little motor oil on the threads, not anti-sieze compound. I learned that from a mechanic when I was a kid and have always done it, and have never had a spark plug that would not come out easily. I know some folks really like anti-sieze, and would agree, use the graphite/gray anti-sieze, if at all, not the copper stuff. But use it very judiciously, that is, put only a small amount on. You don't want a big blob of it on the threads, as this can end up in the bottom of the spark plug well and can collect a bunch of dirt down there that will be hard to get out. That's why I prefer a drop of motor oil on the threads. Much less chance of making a mess down there.

Also, rather than inserting the plugs with a socket, I usually use a short length of rubber hose that slips over the ceramic part of the plug. I've done it with the socket and an extension detached from the ratchet handle, but the rubber hose makes it much easier to find the threads in a deep well and get the plug started without cross-threading, IMHO.

 

Nice tips. Thanks again.


( for grins, here's a spark plug anti-seize compound that has all of the above in it, aluminum, copper, and graphite! http://www.permatex.com/products/automotive/b_lubricants/specialty_lubricants/Permatex_Anti-Seize_Lubricant_a.htm )

 

Great writeup!!!

Thanks,
Dom

 

that's like an opulent french meal, where you enjoy all the hors d'oeuvre, main course and dessert together at the same time

But without kidding; it's all the correct application for the correct product.
Another example for wrong usage of copper paste; some folks use them for the back of brake pads to eliminate squealing and prevention of rust between brake pad and brake piston.
But due to the mineral oil base of the copper paste it leads to trouble because the mineral oil affects the rubber material of the piston boots while in contact with the back of the brake pad, what's almost inevitable with new pads when the piston is fully retracted inside inside the caliper bore.
I see damaged brake caliper boots all the time and I'm fairly sure, that only a small percentage is damaged by unappropriate tools like wire brushs, but the rest is affected by oil based substances on the back of the pads.

Best Regards from Germany

Martin

 

Nice thread! ...but I'm confused now.
Permatex specifically states that their Copper Anti-Seize Lube is good for "...spark plug threads installed in aluminum".

Is Permatex wrong?

http://www.permatex.com/products/Automotive/lubricants/specialty_lubricants/Permatex_Copper_Anti-Seize_Lubricant_b.htm


Regards, Richard

 

I use Phil Woods green bicycle grease myself! Just a really tiny amount works fine.

Ken

 

sorry, but based on latest experiences and engineering research.... yes, they are wrong.
But others too insist on recommendation of copper compounds for use on aluminium - steel joints. Especially in long term applications problems are worst.
Like already mentioned; I have seen Alfa Romeo heads where the plugs weren't changed for years and installed with copper paste in the past.
Then there was a stone like (!) substance, which tore the thread apart while trying to remove the plugs.

I will never forget the mess with my aluminium wheels with copper paste on the centering hubs.

Best Regards from Germany

Martin