'06 5.4 with 339,000 blew a plug.
Towed to shop and they cannot get the new plug to thread in far enough to seat and torque. Thread and hole appear clean and clear. Wrench says, as if the plug is hitting the cylinder wall or something.
I get nauseous at the thought of retirement of her.
Suggestions anyone?

 

If it blew a plug was the spark plug hole repaired, and if so with the correct size?

 

Thanks for your help.
No, the plug just blew out and my wife went right to the shop. They suspected possible thread repair but all looked good until they tried to seat the new one.
Also, the other 7 plugs were all loose as well.
Thanks for your interest.
Still puzzled.

 

They should run a spark plug thread chaser down the hole just to make sure the threads are straight and clean.

Also makes sure they're using the specified spark plug.

 

They say that they ran the extraction tool all the way down with no problem.
I saved an older previous set of plugs under the back seat. I asked them to try one of those just to see and compare with their new one. No word on that yet,
I will have to ask about the thread chaser. That's a wise suggestion. Because don't know how far their extraction tool goes in.
Thanks alloro, again, will keep posting of any progress.

 

I must say I'm amazed by this whole issue since it isn't rocket science. Spark plug has threads, hole has threads, spark plug fits in hole, spark plug tightens down...done.

 

Hahaha I know what you're feeling!!
When all is said and done, I'm hoping that it's just someone had a brainfart and is willing to admit to it.
Thanks for letting me smile a bit, awaiting the results.

 

Would _generally agree_, Except---- This particular engine has a squirrely design plug that extends way beyond the threads. Wonder if 'carbon buildup' in the hole in the head (the crap that seizes plugs and breaks them off) is keeping the plug from going in far enough to engage the threads???????


That is the reason I recommend cleaning the carbon out of the extended hole in the head before installing new plugs.

 

Good thought. I will suggest that to the shop Monday morning. Though, they tell me the threads and the hole visually appear clear, clean and they ran an extraction tool into the threads with no problem.
The new plug goes in but not far enough to seat by hand and they are hesitant to force it to torque. They said as if it was hitting the cylinder wall???
Additionally, they reported that the other 7 plugs were found to be loose, although they haven't pulled any of those yet.
Thanks for the thought and suggestion.

 

I have some reservations about what your mechanic is telling you.


The extractor tool does not have the long snout on it like the plugs do. (It's purpose is to remove the long snouts that have broken off in the head anyway).


Second, there is no way anybody can see down in there.


Are they sure the extended part of the old plug isn't broke off in the head - waiting for the extractor tool to remove?

 

I will talk to him Monday. Would be great if I could put eyes on the problem but stuck 2500 miles away for awhile with family emergency when this happened while she was driving.
I've been trying to see a cutaway view of a head, haven't found one yet.
Thanks for the info and photos of the plugs. That all makes sense, shops version is confusing.
Thanks for the thoughts and input.
I will post ANY progress, as I get it.

 

Maybe this will help.






ford_three_valve_spark_plug_cylinder_head_cutaway

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Ford-3v-chamber-hemi-apex-shape

 

Yes. Thanks. Now I have an idea of what could be happening. And I see what and where you are talking about.
Thanks Torque

 

Don't you just love pictures!

 

And emojis 😂 😍 😘