Cracking spark plugs

Although your meme made me giggle, the OP has been a part of the community for a long time back when MSF was active.

So I doubt he would be one of those guys to overtighten or improperly gap plugs.

 

Yeah mine also cracked and I def did not over tighten them. Not my first rodeo.

 

You know everytime I read a post in your build thread, and all the helpful How-To's you've made from it. I did sometimes stop and wonder.... "Does he Incredible Hulk his spark plugs?"

 

I mean, I’m a flawless master mechanic, too. The straps on these plugs are pretty brittle though. I’ve broken one myself and I had the ceramic on another plug crack on me. It was more of an admission of guilt than an attack. My bad plugs were my fault. [emoji23]


Sent from my iPhone using Tapatalk

 

Back in the day I've had Bosch and Denso's crack from looking at them too hard.

NGK's were always much stronger and durable, so they've been my plug of choice for a while. This whole thing about the cracking ceramic though is really weird.

 

So initially the spark plugs were tightened in this engine by the Mazda mechanic who built my engine using a torque wrench. Or all 3 of them actually.
Then they were tightened by me in the parking lot but I'm still sensible and I kind of know how to tighten a spark plug, these are not the first ones that I've changed on my car. However,only with this engine I've had this problem.
I've gapped all the spark plugs on my car since 2011, so it's a bit weird that suddenly in 2019 I started doing something wrong, on 4 sets of spark plugs.
Let's just say we can safely rule out any spark plug tightening or gapping problem.

Although I was tempted to assume that all the NGKs I had were in an ultrasound storm then what was the catch with the Densos? They cracked even worse and nailed the last stud in this engine's coffin.

It indeed, especially that first the ceramic insulator was cracking on the coil boot side, not inside the cylinder. So the "type 2" insulator breaking described here:
http://www.ngk-sparkplugs.jp/english/techinfo/troubleshooting/04/index.html

Also what they say there kind of makes sense:

So I'm thinking that the engine was knocking quite a lot in other situations and this is what was affecting the spark plugs. During WOT pulls everything looked normal.
When logging the only situations when I was seeing quite a few degrees of retard were the usual ones, when cruising right at those loads and engine speeds when the knock sensor is and then is not listened to: 0.4-ish load, 2500-ish RPM.
Because of this I started to think maybe I had a problem with some of the injectors which were swapped at some point but did not make the problem go away: one of the sets was used and I sent for cleaning and flow testing, the second one was from my car the original set which I also sent for cleaning and flow testing to the same company.

Then it's the WMI. Maybe if one of the nozzles does not atomize properly then those drops can expand suddenly after the combustion occurs. If they end up in the spark plug area then they may be the cause for those deposits, just as well as the improper spray pattern of the DI injectors could be causing similar issues (but these were properly tested in a specialized facility though).

Then there's the CS cam shafts with the wider opening. Maybe these in conjunction with the Crower valve springs cause some harmonics or vibrations that lead to these issues shortly after a new spark plug is installed.

My biggest fear now is that I will rebuild the engine and end up with the same issue because of something else which I will put back on the car without knowing that caused the issues.

Right now I'm deciding between buying a fully built engine from SP63 or rebuilding the other block I have. My machinist just messaged me and told me that the old block can be bored to 88mm and used again.

 

Shiiiit... if it’s vibrations, I would be replacing plugs daily. My car has ALLL the vibes. lol

On a side note, my cracked plug was brand new, so if they all seem to be doing it brand new maybe it is, in fact, related to vibrations and some plugs are just vibrating apart while others are strong enough. [emoji2371]

Sent from my iPhone using Tapatalk

 

I would not buy a s6p3 motor. Their quality has been inconsistent.

 

Maybe there's a bad batch of NGKs floating around? Pallet dropped from 4 story building? Aside from the gap opening up on me, I haven't had any issues with NGKs in any application. Have you considered those fancy Brisk plugs?

 

you guys get fake plugs perhaps?

 

Nope, the spark plugs were fine (all sets purchased from Edge). There's something going on with the head in my case, some vibration probably from the CS cams and stronger springs.
I'm in the process of rebuilding now, I'll build a completely new engine and I will tear apart the current one when I will have time.

 

Ok, sorry to resurrect an old thread, but there's one thing that hasn't been mentioned here. I couldn't find whether anti-seize was used when installing the plugs, but if it was, that could be the problem. NGK plugs do not need anti-sieze, in fact doing so will cause them to be overtightened. From their website:

NGK spark plugs feature trivalent plating. This silver or chrome-colored finish on the threads is designed to provide corrosion resistance against moisture and chemicals. The coating also acts as a release agent during spark plug removal. NGK spark plugs are installed at the factory dry, without lubrication or anti-seize.

Anti-seize can act as a lubricant, altering torque values up to 20 percent, increasing the risk of spark plug thread breakage and/or metal shell stretch. Thread breakage can sometimes involve removing the cylinder head for repair. Metal shell stretch changes the heat rating of the spark plug and can result in serious engine damage caused by pre-ignition. Do not use anti-seize or lubricant on NGK spark plugs. It is completely unnecessary and can be detrimental.

I also found this on their web site, which is more relevant to the OP's issue:

Over torque can cause the metal shell of the plug to stretch. The threads can crack and/or break off. Stretching of the spark plug metal shell can break the inner gas seals or cause a fracture in the spark plug insulator. The most dangerous result is pre-ignition when the heat dissipation is reduced due to metal shell stretching by over torquing. In short, over torquing can cause severe engine damage.

Maybe everyone already knows this, but I thought I'd post it just in case.

 

This is good info, thank you for your reply.
However in my case the case was different. I'm at the 3rd engine after that event, and none prior or after that one developed this issue. I always torque the spark plugs the same way, so something was up with that head or engine. I don't know what it was not even to this day, I still have that head in my shed and one day I will rebuild it because I'll either break another engine on my 3 (uncrowned ZZB king of the world here, I'm on the 7th engine on that car ) or I will need it for my CX7.