What causes spark plugs to crack

Ian_Olivas · Sep 26, 2017

So I kept on getting a misfire for piston 1 and thought it was my remote start that had a wire spliced into my coil #1 causing the issue. Well I tested that and no it wasn't my spark plug was cracked so I replaced it and it's been about a week and I have another misfire on cylinder 1. Tomorrow morning I will pull the plug to see if it's a cracked plug or not but I'm getting money it is. And this will be the same cylinder that all the misfires happened on and the same cylinder for the previous cracked plug. And it's been less that 300miles since I changed that plug. Also I'm concerned the when I use the remote start that it could be causing the plug to crack. How could I test this to see if it is or isn't?

Ian_Olivas · Sep 26, 2017

The plugs shown didn't even have 6k miles on it yet

Ian_Olivas · Sep 26, 2017

I also had a bank 1 too lean code pop up a while back like maybe 2 weeks ago. Thought it might be from the misfire, haven't seen it since. Could running lean cause the plug to crack?

fastf · Sep 27, 2017

First what brand plug you are running .Most of your Magnium engine use plan old Champion copper core .You can ask most the people in the forum what they run Ngk would be my second pick .I would do a engine scan and see whats causing it to run lean on that bank it will show whats going on.

RonJon '06 · Sep 27, 2017

Clogged fuel injector?

fastf · Sep 27, 2017

Don't think a clogged injector would cause the porcelain to crack but am not ruling that out too .There is stuff that can clean a injector out there without taking them out.I also seen something like this years ago what heat range are the plugs you are using too.If they are too hot they will crack like that .

Jerseystyle · Sep 28, 2017

fastf said:
Don't think a clogged injector would cause the porcelain to crack but am not ruling that out too .There is stuff that can clean a injector out there without taking them out.I also seen something like this years ago what heat range are the plugs you are using too.If they are too hot they will crack like that .

I was thinking the same thing; too hot. I really don't think a lack of fuel would cause that.

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Ian_Olivas · Sep 28, 2017

fastf said:
First what brand plug you are running .Most of your Magnium engine use plan old Champion copper core .You can ask most the people in the forum what they run Ngk would be my second pick .I would do a engine scan and see whats causing it to run lean on that bank it will show whats going on.

I'm using the oem champion copper core plugs. Part# RC12MCC4
And what's an engine scan? Like obviously it scans the engine but what tool does this and where can I go to get one done?
Also update on this. I pulled the plug from cylinder 1, the one that I just replaced and also just misfired and it wasn't cracked and nothing looked wrong with it. I did notice some metallic flakes on the threads themselves though and it kind of looked like I had oil on the thread part that would exposed in the combustion chamber but not on the electrode itself. And last night it misfired again I cleared the code so incan tell when it will misfire again

Ian_Olivas · Sep 28, 2017

Jerseystyle said:
I was thinking the same thing; too hot. I really don't think a lack of fuel would cause that.

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I was told that if you run too lean and there's not enough fuel it will cause spark created to basically make the cylinder over heat and crack the plug or cause detonation

Jerseystyle · Sep 28, 2017

Ian_Olivas said:
I was told that if you run too lean and there's not enough fuel it will cause spark created to basically make the cylinder over heat and crack the plug or cause detonation

Good point.

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fastf · Sep 29, 2017

A good scan tool is like a code reader but it will show the engine firing and can go deeper into the the computer on your truck a code reader cannot and it reads which cylinder is running lean.A repair shop will have a good scan tool because its a must or you know someone you could borrow it for a second.

fastf · Sep 29, 2017

What do you have those plugs gapped at ?A close gapped plug will cause it to burn up the plug like that too and if you are having detonation check your knock sensor.

Ian_Olivas · Sep 29, 2017

fastf said:
What do you have those plugs gapped at ?A close gapped plug will cause it to burn up the plug like that too and if you are having detonation check your knock sensor.

But if it's the knock sensor it should be throwing code right? And also i gapped them ar .04 and now that i think about it, it should be .035 right? Would that .005 difference cause this?

Ian_Olivas · Sep 30, 2017

Update: still have not had a misfire since I created post, I ran a bottle of seafoam on half a tank (13gal) in case it was a clogged injector. I'll run another bottle in a few days. Truck drives fine and nothing yet

fastf · Sep 30, 2017

I had a Knock sensor leak oil right through the top of the sensor and not send a code.I looked up your plug gap that you just wrote you have your gap too close the plugs need to be set at .040 inch not 035 .You are burning up your plugs up .Plug gaps on new cars and trucks engine have a larger plug gap because the spark is so much hotter.I can remember when plug gap was 029-035 and the points were about 015 heck if you didn't have a feeler guage use a book of matches end to set the points.Now with electromic control your spark is a lot hotter.The best advise for you buy you a service manual for your truck it will save you a bundle of money and yes you have some smart guys in this room but some of them never turned a wrench in their life and go by what someone has said or quoted or what a mechanic may tell you and sometimes he may be wrong.One more thing .005 is thousands of a inch .035 is 35 thousands of a inch .

RonJon '06 · Sep 30, 2017

fastf said:
I had a Knock sensor leak oil right through the top of the sensor and not send a code.I looked up your plug gap that you just wrote you have your gap too close the plugs need to be set at .040 inch not 035 .You are burning up your plugs up .Plug gaps on new cars and trucks engine have a larger plug gap because the spark is so much hotter.I can remember when plug gap was 029-035 and the points were about 015 heck if you didn't have a feeler guage use a book of matches end to set the points.Now with electromic control your spark is a lot hotter.The best advise for you buy you a service manual for your truck it will save you a bundle of money and yes you have some smart guys in this room but some of them never turned a wrench in their life and go by what someone has said or quoted or what a mechanic may tell you and sometimes he may be wrong.

If I'm reading his previous post right he's got them gapped correctly at .040".

I suggested a clogged injector because the hole looks hot, it's misfiring and throwing a lean code on the same side. If the misfire comes back I'd try swapping the injector with another cylinder and see if the misfire follows the injector.

fastf · Sep 30, 2017

I'm looking at .04 not .040 and then he set them at .035 read the post again I'm looking at they weren't gapped at all but I maybe wrong .If he has them gapped too close the electrode maybe getting to hot and cause the porcelain to crack.But if he is happy with it I say go for it.

justin13703 · Oct 1, 2017

fastf said:
I'm looking at .04 not .040 and then he set them at .035 read the post again I'm looking at they weren't gapped at all but I maybe wrong .If he has them gapped too close the electrode maybe getting to hot and cause the porcelain to crack.But if he is happy with it I say go for it.

.04 and .040 are the same thing.

He said he had them gapped at .04, which is the same as .040. So he has them gapped correctly.

fastf · Oct 1, 2017

justin13703 said:
.04 and .040 are the same thing.

He said he had them gapped at .04, which is the same as .040. So he has them gapped correctly.

.04 thousand of a inch isn't .040 thousand get you a feeler guage and look .04 is real thin guage like used to set the gap on a valve .040 isn't.

chrisp2493 · Oct 1, 2017

fastf said:
.04 thousand of a inch isn't .040 thousand get you a feeler guage and look .04 is real thin guage like used to set the gap on a valve .040 isn't.

That's not right. That's not how math works. Are you sure it's not .004? That's 4 thousandths of an inch. .04 and .040 are both 40 thousandths of an inch

What causes spark plugs to crack

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