Blew a Spark Plug Out!

[galaxy]

Yes, you read that correctly. (this is on my sons '12, Gen I engine, but...thought I'd sneak it in here since still 5.0 and you guys are good to bounce stuff off). Stock engine sans Boss intake, headders, Lund tune, the standards. I think he was running E85 (flex tune) when it happened.

Got the car home and in the garage. To the upmost best we can tell, it looks like the plug backed out as opposed to the threads failing (a la Triton engines). I mean, there's no way all the threads failed and launched a plug, right? Just no way. I have an inspection camera, and inside the cylinder looks good. No damage to the piston (no holes) or the cylinder walls that you can see. I wish you could flip that camera over and see the bottom of the head (valves), but no way.

The camera also reveals that the threads in the head are intact. Can clearly make out all the threads. The inside of the plug bore accessing the plug (where the coil pack boot would be) is darkened from what looks like maybe a flame front came up through there. The spark plug seat area (top of the threads) is hammered up a little bit from what looks like the spark plug bouncing around until he could get stopped and shut down. The coil pack is completely demolished. I need to attach some pics because it looks like it went through hell.

The ground electrode is completely broke off and missing from the plug, and we can't find it. Left to assume it broke off bouncing around in the bore once ejected.

I tried to start a new plug in the hole. It will turn a couple threads and then stop. I didn't force it. Need to go get a spark plug hole chaser and clean it out; have not done that yet.

Motor turns through, piston swings just fine. Unplugged the coil (obviously) and the fuel injector for that cylinder and it cranks and runs simply like it's running on seven. Cranked it up to get it on a trailer and in the garage and all that jazz. All spark plugs were previously gapped right, and torqued to 10-12 ft lbs. Nothing in the oil, etc, etc.

So that's the jist of the background info, unless you guys got questions.

My questions and ideas to bounce off you guys are this...

From what we've found from inspection, my logic is to chase that hole, install a new plug, and fire it up. Is there anything else you recommend doing in addition to that? I thought about actually pulling a valve cover, but I don't know what, if anything at all, an inspection from the top side would reveal.

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[dirtwarrior]

When you chase the threads coat it with grease to catch what ever fall out of the hole. Go slow clean chaser then recoat with grease. If you feel any obstruction go slow back it out clean start over go a little deeper.

 

[sk47]

When you chase the threads coat it with grease to catch what ever fall out of the hole. Go slow clean chaser then recoat with grease. If you feel any obstruction go slow back it out clean start over go a little deeper.

Hello; yes to this big time. Also if you can find an adaptor to a shop vac to stick in the plug hole to pull out any loose bit that may fall in.

One other thing. There are thread chasers and there are thread cleaners. I think the thread cleaners are less aggressive. Might be worth a try.

Years ago I did some work on my fathers 351 C V8. This was an iron head engine. One of the plugs was so loose I could remove it with my fingers. I replaced the plugs and torqued them. All was fine. I do not recall if I chased the threads.

Good luck.

 

[Biggus Dickus]

Who may I ask put this particular spark plug in? And how are the threads on the spark plug? Was it a defective spark plug? Anyways, sorry for your troubles but I am really curious as to what caused this.

 

[galaxy]

Thanks guys. And yes, I know about the grease. Have fixed many a Triton spark plug hole.

Who may I ask put this particular spark plug in? And how are the threads on the spark plug? Was it a defective spark plug? Anyways, sorry for your troubles but I am really curious as to what caused this.

Yours truly put that plug in. And torqued it. The threads on the plug look normal to me; nothing that looks like galling or head material imbedded in between the threads (need to get some pics up for you guys). Plug does not look defective in any way. I'd love to know what caused it, but the evidence thus far simply implicates that it just backed out.

 

[galaxy]

Thanks to you guys that wished me luck, but alas, it was not to be.

Started with the thread chaser. It screwed in about four threads and came to a stop just like a new plug did. I tested the waters to see how much effort it would take to continue on. So I tired. Then it felt like it would push through. But alas, it did not. Now the chaser threads in a few turn and just spins. Can’t get it to bite on any thread to continue down into the hole. Sooooo, she’s buggered.

I guess I could try and take a normal 14x1.25 tap to the hole and see what the results are. Short of that, looking at some type of thread repair.

I know TimeSert is an industry leader and faaaarrrr from your typical heli-coil or auto parts plug repair place.

You guys got any other thread repair recommendation?

 

[Basspro302]

Ive used the calvan kit for 5.4 2valves all the time. Ive used it on other cars but haven’t had the pleasure of trying it on a coyote.
Make sure the valves are closed when you drill and tap. Use wheel bearing grease on the tap and bit it will catch most of the chips as you drill. I usually clean the bit multiple times and reapply the grease.
Also get something like a brake line to put down into the hole and blow the chips out.

 

[galaxy]

TimeSert going in! Do it right and forget about it.

 

[SLOBullitt]

TimeSert going in! Do it right and forget about it.

+1 on the TimeSert. Had to buy a kit when my ford Escape launched a plug. It was pretty easy as long as you follow the instructions and have a air compressor to blow out the chips. End result was nice. Considered doing the other 5 plug threads but never got around to it before my teenager ruined it 4 wheeling. Yes, I know! Kids!!! Still got the kit, minus 1 insert used.

 

[galaxy]

Sorry...forgot to update this thread for anyone that cares. TimeSert saves the day again. Every other hole in the head will fail before this insert does!

If interested, 4412E is the correct kit, and 44187A is the correct aluminum insert for a Coyote head. Straightforward job, tools work like a champ, etc, etc. You can't say enough about these guys.

Car is back together and runs fantastic after the blow-out. We never did find any evidence or signs of what made the plug back out or blow. It's a darn unnerving job tapping a spark plug hole, but all went well.

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