Spark Plug Blowout

crzyhrse99 · Mar 5, 2007

After reading all of the horror stories over the past couple years, I was the latest victim this morning going to work . Luckily, I had just left my driveway when it happened so I just parked it and took my the wife's car to work.

I got home and took a look at it, the COP was broken loose from the 8mm bolt that holds it down and it was just lying on the vavle cover, the rubber boot was gone and just the spring was still attatched.

I got a flashlight and looked inside the well and only the electrode and the part that grabs the socket to loosen/tighten were all that were left. The white part of the plug and the tip that goes to the cop were gone .

The good news was that it actually came out, I dropped another plug in and it tightened down to 13ft/lbs . So I guess I got really lucky this time. I looked online at autozone,advance, and these COP's are like $50 for some knockoff brand. Any of you guys know where to get these at a better price than that or can I get Motorcraft for that price at the stealerships?

LaserRed01GT · Mar 5, 2007

Was the ground/hex shell actually ejected from the threads in the head or was it still screwed in?

crzyhrse99 · Mar 5, 2007

LaserRed01GT said:
Was the ground/hex shell actually ejected from the threads in the head or was it still screwed in?

It was still screwed in, I had to break it loose. I ended up using a coathanger to fish out what was left of the plug.

00PearlGT · Mar 5, 2007

Were these the stock plugs or ones you installed yourself?

jeffnoel · Mar 6, 2007

MSD nows sells a COP for us you can get them individually or a set if 8.

LaserRed01GT · Mar 6, 2007

crzyhrse99 said:
It was still screwed in, I had to break it loose. I ended up using a coathanger to fish out what was left of the plug.

That's strange. When you said "blowout" I thought you meant it actually ejected the spark plug from the head like they usually do. That sounds more like an electrical resistance problem that overheated the plug and blew it up.

Can you post a picture of the plug?

Dusstbuster · Mar 6, 2007

Yeah thats not a normal "blowout" by the sounds of it. The term "blowout" usually refers to a plug slowly loosening up in the head itself over time and then when it crosses the threshold of lost torque that the cylinder compression can manage to blow the plug AND threadings completely out, ruining the head and destroying the plug. Yours sounds like something far different, especially if the plug was still seated in the head.

By the way I hope you let the engine cool down completely before you tried removing the plug...

crzyhrse99 · Mar 6, 2007

The plugs were Autolite coppers with about 10k on them if that. Pics coming soon if I can figure out how to host them.

crzyhrse99 · Mar 6, 2007

jeffnoel said:
MSD nows sells a COP for us you can get them individually or a set if 8.

I'm looking for something local that I can pick up tomorrow, this is my DD but thanks.

StangYellow · Mar 6, 2007

Make sure you put some copper Anti-Seize on those plugs or else you will really get a "blowout"

crzyhrse99 · Mar 6, 2007

This is all that was left in the plug well.

LaserRed01GT · Mar 6, 2007

That could have been two possibilities. There is a condition with spark plugs called flash over. As the ground electrode and center electrode wear over time, the gap is effectively widened and this raises the voltage requirement to fire the plug. The flash over occurs when the required voltage between the two electrodes is higher than the voltage being conducted between the terminal (where the COP spring touches) and ground shell. This can cause the electricity to jump from the terminal straight to the outside of the ground/hex shell.

The insulators on spark plugs is actually caulked to the ground/hex shell. Flash over puts a bunch of heat into the plug, and I bet the caulk was deteriorated so badly that the compression in the cylinder finally gave it the boot. Plus Autolite plugs are junk anyway. I've see tons of problems with Autolite plugs.

Those plugs look filthy. A dirty plug insulator is the primary cause of flash over. Are all your plugs that dirty?

crzyhrse99 · Mar 6, 2007

LaserRed01GT said:
That could have been two possibilities. There is a condition with spark plugs called flash over. As the ground electrode and center electrode wear over time, the gap is effectively widened and this raises the voltage requirement to fire the plug. The flash over occurs when the required voltage between the two electrodes is higher than the voltage being conducted between the terminal (where the COP spring touches) and ground shell. This can cause the electricity to jump from the terminal straight to the outside of the ground/hex shell.

The insulators on spark plugs is actually caulked to the ground/hex shell. Flash over puts a bunch of heat into the plug, and I bet the caulk was deteriorated so badly that the compression in the cylinder finally gave it the boot. Plus Autolite plugs are junk anyway. I've see tons of problems with Autolite plugs.

Those plugs look filthy. A dirty plug insulator is the primary cause of flash over. Are all your plugs that dirty?

Well I have never heard of flash over, but I guess that makes sense. The problem with the dirty plugs is that I cant keep water from seeping into about half of my plug wells. The water is coming from the honeycomb panel rivets unerneath the hood and it pools up around the COP. I have caulked them up but I guess its not working.

LaserRed01GT · Mar 6, 2007

Yeah, try to do what you can to keep that water out of the plug wells. There is a pretty good chance that some or all of the COP's may be hurt on the plug wells that were getting water in them. Water in the plug wells can also cause flash over problems.

crzyhrse99 · Mar 6, 2007

LaserRed01GT, thanks for all the good info. Im going to pick up a new COP tomorrow along with some di-electric grease and take all of them off, clean them, put some grease on the springs.

Another question for ya, could I use some of the RTV gasket stuff and put a small bead around the plug well to keep moisture out? That's probably not the best thing to use but I'm just trying to think of somehow preventing this in the future.

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