I just experienced the dreaded "blown spark plug" on my 2001 5.4 L.

The bottom of the plug threads have what looks like aluminum deposited on them: I assume it is from the head, and not a failed attempt at heli-coil repair by the unknown prior owner.

The thing that really concerns me, and causes me to ask for help, is that the side electrode is bent over the center electrode; there is no gap, in fact the side electrode is bent around and over the center electrode.

Obviously something smacked it, hard.

Hopefully it was caused by something other than slamming into the top of the piston, but that is my fear.

Could the plug have failed on an intake stroke, such that it was initially drawn into the head?

Then when the piston came up again: smack. Ouch.

Or would the plug, upon failing, always be blown outward such that the likelihood of contact with the piston is nil?

If so, the bent electrode would have been caused by repeated violent impacts with the spark plug well / cylinder head, I would guess.

My initial plan was to pull the cylinder head, but that would be a waste of time if I found out that the piston was holed: then it's time to pull the engine.

Any tests or methods I can employ now to see if the piston is damaged, that don't require removing the head?

Constructive suggestions as to this dilemna?

Thanks.

 

well the only thing i can think of is take a flash light and look down the spark plug hole to see if you can see if there are marks on the top of the piston that would be from hitting the plug.

 

was there any signs prior to this happening? just curious to know. sorry to hear about it man

 

No prior signs at all, no hissing, no drop off in performance.

It happened during normal operation, no WOT or anything like that, just out of nowhere it sounded like a massive exhaust leak.

It happened close to home, thank god.

The plan is to remove both heads and inserts put in.

 

i feel yer pain this also happened to me just driving 30mph to take my girl to her car then...boom.. right out of the hole and plug and coil pack..had to helicoil it and it worked fine till i built the motor

 

If it had caused serious damage to the piston, you would know it. You would either notice a lack of performance due to a hole in the piston or you would hear a chunk of the piston rattling around inside the cylinder.
I had a plug blow out on my truck a couple months ago and it did the same thing to the plug.
It was likely just caused by the plug ratting around inside the hole, but it wouldnt hurt to check the piston if you can.

 

Mr. V- The thing to do is borrow a bore- scope. Do you know what that is? It's a thin fiber-optic scope that you can go in the plug hole with and take a look around. Next best thing is a thin necked flexible flash light. The neck is about 6-8 in. long and bendable and only about 3/16 in. in diameter. It's kind of hard to use a regular flashlight because to get the light down the hole to see then the flashlight is in your line of vision. You can get the light down inside the cylinder with the thin neck and really get a good look (unless it's a rear cylinder where it's hard to see under any circumstance), other wise the best thing is the bore scope. You don't have to pull the heads if you're using the helicoil inserts (though I would prefer the timeserts). DON"T USE the regular helicoil for a stripped thread, use the one for stripped sparked plug hole. It may be quite a bit of work to do them but not as much as pulling the heads and also the cost of head gasket set and new head bolts. If I knew where you lived and it was close enough in the So. Cal. area I'd loan you a bore scope. If you don't have any piston damage I'd forget pulling the heads. Good Luck!
P.S. If you can't find the thin necked AA flashlight to borrow, they did sell them at Sears, and probably still do. If the plug "blew" my guess would be that it was damaged by "sudden stoppage" when it hit whatever stopped it. If that piston got up far enough to pound that plug (I doubt it), then you do really have a problem.

 

Very sorry to hear that man, I feel your pain. My f150 xlt 99 started to misfire but runs well when engine heats up, then" service engine soon "was on. I removed the battery and removed the hi-tension wire and pushed them back on. After, the service engine soon went off and truck runs perfectly again. Every time I used my truck more than 40km same problem occurs. On my thread one suggests that the 3rd spark plug is beginning to popped out. Do you guys think that what I'm doin would damage my engine. I checked all my plugs and all were ok and tight, if its popping out, would I feel it loosen up? I'm afraid to use my truck on long drive. Guys, hope you can help me out.
Thanks and God bless

 

You do not have to pull the head to put a Timesert in. We have a member "Galaxy" that rents a Timesert kit. Scope the cylinder, if it's clean, get the kit.

 

One of the first signs of a plug on it's way out is it will sound like a collapsed lifter. Tighten up the plug in the area that you hear the ticking. If you don't feel comforable that you got the right one tighten them all, it is well woth the effort. The bent electrode most likely happened when the plug hit the underside of the hood. It comes out with a lot of force. I have blown one and stopped another before it happened. Up here in Canada & likely in the US parts stores ore now carrying a $70.00 insert that cuts its own threads. Once you have replaced the threads. Do a compression test. It will soon tell you whether there is or is not a hole in the piston.

 

The odds are extremely slim that the plug contacted the piston. Mine blew twice, both times the plug looked as you described, and inever had any contact. My rough speculation (and no one laugh) is the force from literally blowing the plug out the hole caused the ground to bend down like that. That's a lot of friggin force to blow a spark plug clean out of the head...bad threads or otherwise.

Which cylinder is blown? As already mentioned, visual is the best inspection method when suspecting something like that, but a compression test will tell you results as well.

As also mentioned, please contact me about renting my TimeSert kit. It really is THE ONLY WAY you should consider repairing the hole. It'll last forever, it's cheap, and if you can change oil and follow simple instructions, you can install a TimeSert in hour driveway with basic handtools before lunch...literally. Shoot me a PM anytime!!

Thanks GLC!!

 

The only thing better than a Timesert is a custom insert from blownoutsparkplug.com.