Seriously, 4.6L just shoots plug out of block?

[ab_slack]

Was out this evening. Had taken our 2002 Explorer with 4.6L.

All had been fine. When we went to leave, cranked the engine, it started and a second later it starts making horrible and loud noise. Shut it down immediately. Initial thought was that some serious mechanical failure occurred.

Opened the hood, didn't see anything obvious, so restarted while watching engine, immediately it was obvious sound was coming from a spark plug hole. Pulled the engine cover and found plug and coil pack had been blown out with the plug still in the coil pack and the whole assembly hanging by the wire.

What the heck causes that to happen? Got a plug socket, ratchet and extension and was able to put the pug back it. Thrads on the plug seem fine and it didn't seem stripped. So my only guess is that the plug must have been loose. It been over three years since they were worked on. Loose all that time? Seemed to be running perfectly fine. Only hint of anything is that it seemed to have a tapping sound that had been getting louder. When I get the coil pack replaced (it was damaged beyond re-use) I will see if it has that "tap" or if it got quieter.

I am just dumfounded that this happened.

 

[Mac]

Common problem with some of the motors, just do a Google on that problem. Seems to be not enough threads.
Dave
http://www.city-data.com/forum/automotive/1901648-blew-spark-plug-ford-4-6-a-2.html

 

[ab_slack]

Thanks, I never heard of that. Now I have some idea what can be done about it.

Update, got new coil pack in the morning, it is running fine. Drove it 250 miles today home without an issue.

As far as the apparent tap, I can't say it is better or worse. On our way out yesterday evening, about 15 minutes before reaching our destination we went thru a toll booth that reflected sound from engine well. It seemed abnormally loud compared to similar circumstances (like going thru a drive thru for food). Initial impression is that it is better than that particular time but not necessarily quieter than other times I have noticed the tap.

For what it is worth, 321 miles mostly highway with about 15 miles on 7 cylinders in those 321 miles I got 17.7mpg. With new plug and coil pack, same percentage highway, filled up when we got home after 116 miles and again got 17.7mpg. This second measurement is probably sloppy as not many miles so fill level variability when filling the tank causes bigger error. But I think it is close enough to conclude there probably wasn't any real operational issue until it coughed up the plug..

 

[RonD]

I assume you checked the other spark plugs for tightness

 

[ab_slack]

I assume you checked the other spark plugs for tightness

Not yet, but that is a good idea. Hadn't occurred to me, had I done so I probably wouldn't have checked while out on the road with the limited tools.

The real question I have in my mind is this one can be trusted. I don't know if it was loose to begin with or threads gave out (possibly over torqued). This is a remanufactured engine that was put in three years ago. Plugs either came with the engine or were put in by the shop that installed the engine. I am pretty sure the coils were off the old engine.

Other than replacing a blown heater hose I haven't done anything with this engine other than oil and coolant changes.

 

[RonD]

That "tapping, ticking" noise could be another loose plug

 

[ab_slack]

ticking...as in ticking time bomb seems perhaps appropriate.

I am glad this didn't happen when I loaned the car to my daughter the other day when she blew out a tire..

And because I loaned her the car, it mean't I had to take my BII on 1200 mile round trip when I got news my dad was in the hospital instead of taking the explorer.

So all in all, if this was gonna happen I am kinda glad the cascade of events worked out this way. Timing could have been better but recovery wasn't too bad.

I'll certainly check the other plugs.

 

[adsm08]

I have never seen or heard of a 4.6 shooting a plug out of the block.

They do shoot them out of the heads frequently though.

It was a design issue there weren't enough threads and the head would give out. A heli-coil kit and 20 min will fix you up.

The plugs were redesigned a few years ago with a longer end and more threads to prevent this, but you still see it from time to time.

 

[straycat]

Common problem with some of the motors, just do a Google on that problem. Seems to be not enough threads.
Dave
http://www.city-data.com/forum/automotive/1901648-blew-spark-plug-ford-4-6-a-2.html

That is for sure. I know 3 people who had the same issue a few years back.

 

[ab_slack]

Follow up here, I checked the plugs on the driver side only. The three next to the one that blew out. They definitely weren't loose. But I discovered that all the plug wells were full of coolant and plugs were completely submerged when I pulled the coil packs. I am surprised that wasn't causing driving problems.

I blew out the coolant, pulled the plugs, plugs looked fine.

Coolant appears to be coming from where the upper heater hose connects. I presume the thermostat is housed there. The problem isn't the top seal, but rather it looks like a three piece assembly and it is the bottom most seal.

So looks like I have to get that resolved now. It was getting late so quit there this evening.

 

[ZMan]

the tapping/ticking is your manifold starting to leak. Those are also known for breaking studs, blowing out gaskets, rotting out, and the y-pipe to manifold bolts rusting/breaking causing a leak.

 

[Tuner710]

Ab_Slack, I have a 1998 with a 5.4 and have had 3 plugs go that way. Yes, too few threads and sometime along the way overtorqueing leads to the problem. There is a kit that is designed especially for repairing this, basically a helicoil insert. Hardest part is access to the threaded hole in the head. Hope you only experience one plug blowout! I can take solace that the numbers 4 and 8 are done on mine, they suck to get at!

 

[ab_slack]

I am inclined to believe that the shop over torqued the plugs when they were putting an engine in. As I have done more and more myself I just come across more and more questionable stuff they had done.

Now I am really bothered by the coolant leak I found last night. I am thinking that might be from cracked plastic intake manifold. In my researching I have found that to be a problem. I wonder though if, during engine replacement, in the transfer from old engine they over torqued causing that problem too.

Hiss at them.

 

[85_Ranger4x4]

Some stupid idiot decided to put an aluminum coolant crossover pipe in the plastic intake manifold (which is also stupid IMO)

With age the aluminum corrodes and swells and breaks the plastic intake. Rockauto has them "cheap"

I am putting intake gaskets on my 5.4 this coming weekend and really hoping my $170 intake isn't cracked.

I have heard it is supposed to be fairly easy to do... famous last words.