i'm a newbie,,,, i was driving my 2004 mazdaspeed turbo , when i down shifted and throttled hard and the 2nd , from the front, spark plug exploded out of the cylinder , completely stripping the theads out ,,,,, anybody no WHY ,, anybody have this happen????

 

Tighten it next time

 

Just like the gentleman before me said, tighten it. .


Also, this a meet and greer sub-forum. Give us some info about you and introduce yourself! I know forums are to ask questions, but use google or our search bar. A lot of the time, the answer is before you as long as you search.

Anyways I'm new as well but welcome to the forums. Please tell us about yourself and car.

 

He swapped in a Triton 5.4

 

Did you perhaps over tightened it? They don't take much torque.

 

Regardless of how it happened:

They make helicoils for that. Tap the head, insert the helicoil, put plug back in. Maybe other brands to, I just talking the concept. You don't have to pull the head is my point. They have kits that include the taps, inserts, setting tool. I've done it on a Honda years ago when the threads came out with the plug.

Do not remove plugs from an aluminum head when it is hot. (not sure how to get a hot compression check, but that is a rule that I have lived by).
DNM

 

 

Wouldn't a hot engine lessen the chance of damage to the threads? CTE mismatch between the alu. head and steel plug threads should increase thread clearance right?

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Only root-crest clearance, which is normally not an huge issue with appropriately fit threads. The mismatch along the plug axis creates extra friction on the thread flanks.

 

Ahhh gotcha, makes sense. I blame running out of coffee this morning. Good to know!

 

Did it on my car. Timesert makes a good kit, $$$ for a one-time (hopefully) use.

 

Probably put copper anti-sieze to be safe, what I normally do.