I noticed a few months ago that maybe one or two spark plugs develop a crack down the insulator. Sometimes it is a hairline crack that is barely noticable, but other times, it is cracked enough to easily catch my fingernail. I have had to replace about 5 spark plugs because of a crack in them. I pulled the spark plugs again today and sure enough, cylinder 4 had two hairline cracks in the insulator. It isn't any particular cylinder either. I believe all of them have had the spark plugs crack. Can anyone shed some light on why this is happening?

They are BKR7E's, gapped to .030", BTW.

Here is a picture of the first time I noticed it and the worst case:

 

from droping the plugs or hitting the plugs with the spark plug tool

you need to be carefull installing/removing them

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Sketch_hs &raquo;</TD></TR><TR><TD CLASS="quote">from droping the plugs or hitting the plugs with the spark plug tool

you need to be carefull installing/removing them</TD></TR></TABLE>

Are you sure? I just replaced cylinder 4's spark plug on Saturday because it was cracked and the new one is cracked again on Thursday.

Can they be cracked just by dropping them in the spark plug hole when I go to put them back in?

 

dont drop them in....

 

that pic looks like the crack started from the top..

have you noticed a pattern in which side the insulator has started to crack from?

 

bro you shouldnt just drop the plugs in...get a small piece of fuel hose or something that can fit over just the top of the plug snugly, and take ur time puttin it down there and just start to screw it in like that, then use the tool to tighten it down fully, i fyou just drop them in more than likely youre also screweing up the gapping on them, as well as damaging them like that.

 

Use a spark plug socket tool...

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by freakie &raquo;</TD></TR><TR><TD CLASS="quote">dont drop them in.... </TD></TR></TABLE>

If they can't survive a 2 inch drop into a hole, how can they withstand the intense pressures inside the combustion chamber? I am really having a hard time thinking that they would crack so easily.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Running925 &raquo;</TD></TR><TR><TD CLASS="quote">that pic looks like the crack started from the top..

have you noticed a pattern in which side the insulator has started to crack from?</TD></TR></TABLE>

The one I posted was cracked from the top, but the ones I pulled out yesterday were cracked at the bottom. There is really no pattern at all.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Das Schmoo &raquo;</TD></TR><TR><TD CLASS="quote">

If they can't survive a 2 inch drop into a hole, how can they withstand the intense pressures inside the combustion chamber? I am really having a hard time thinking that they would crack so easily.</TD></TR></TABLE>

there are other reasons not to drop them in the head.
i had a gap tighten by dropping it in.

i do agree with you that dropping it in is probably not cracking them though.

have you tried using a different spark plug boot? maybe from a friend, see if the problem follows the boot.
it pretty unlikely but it may help eliminate something
hope you figure it out

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Kelly. &raquo;</TD></TR><TR><TD CLASS="quote">

there are other reasons not to drop them in the head.
i had a gap tighten by dropping it in.

i do agree with you that dropping it in is probably not cracking them though.

have you tried using a different spark plug boot? maybe from a friend, see if the problem follows the boot.
it pretty unlikely but it may help eliminate something
hope you figure it out </TD></TR></TABLE>

Thanks for the advice. I guess I will be more gentle with them in the future and set them in more gently.

I also put a new set of NGK blues on last night when I replaced the spark plug, so hopefully the problem was with the old boots and will go away.

 

A standard sized socket set will come with a spark plug tool....That way you don't ahve to drop them in. Eiether that, or like someoen said, use a hose to lower them in. Never drop a spark plug in ever. And remember, the side seeing all the immense pressures are all metal.

 

also when your tighten it down use your left hand to stabilize it so you don't tighten it to the side or anything you can crack it that way too...

 

Good tip as well

 

Conspiracy maybe

 

I seriously doubt a 4 inch drop is causing all his plugs to crack, come on people.

 

Did you buy all these spark plugs around the same time ? Could be a manufacture error, ceramic is pretty tough.

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by 90blackcrx &raquo;</TD></TR><TR><TD CLASS="quote">Did you buy all these spark plugs around the same time ? Could be a manufacture error, ceramic is pretty tough.</TD></TR></TABLE>

I was thinking that too, but I have purchased two boxes of them and I am halfway through the second box. The problem occured with both boxes, so I ruled that out.

I was assuming this problem would be due to something going on in the combustion chamber that I am not seeing like a drastic temperature change that is causing them to crack because of rapid expansion/contraction. I still find it unlikely that a little drop into the spark plug hole would crack the ceramic.

 

^^^^^

if detonation is causing the plugs to crack in the boot, you have SERIOUS problems

hope it all works out,

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by Das Schmoo &raquo;</TD></TR><TR><TD CLASS="quote">

I was thinking that too, but I have purchased two boxes of them and I am halfway through the second box. The problem occured with both boxes, so I ruled that out.</TD></TR></TABLE>

But how close was the date purchase ? I know of one company called vht that had a huge problem with there paint, a batch could be thousands of plugs.

Try switcing brands maybe

 

<TABLE WIDTH="90%" CELLSPACING=0 CELLPADDING=0 ALIGN=CENTER><TR><TD>Quote, originally posted by nsxmatt &raquo;</TD></TR><TR><TD CLASS="quote">I seriously doubt a 4 inch drop is causing all his plugs to crack, come on people.</TD></TR></TABLE>
That’s funny, I have a ceramic plate that is designed to stop a 7.62mm projectile traveling at over 20,000 fps and it says “fragile” on it. If they get dropped at the wrong angle they break. I guess ceramic is funny that way.