Spark plugs blowing out of the head?

[Snakebit]

Not Cobra related, but a co worker has a Ford minivan and this the second time he has had a sparkplug blow out of the head from 2 different cylinders!
I never herd of this happening, any explanation on why or how this could happen?

[CobraEd]

He did not put them in tight to start with ???


.

[patrickt]

I've never seen a plug "unscrew itself" and keep firing while it was doing the unscrewing. If it's the threads on the plugs that are stripped and gone, I might suspect counterfeit plugs. If the threads on the head are gone, then I don't know what to tell you.

EDIT -- Fake spark plugs are a pretty big business. Just try googling it and you might be surprised....

[Tom Wells]

Snakebit,

If it has a 4.6, this will describe the problem and the method for correcting it: http://ww2.justanswer.com/uploads/jm...sb08-07-06.pdf

It's a widely known problem with the 4.6 Ford engines.

If it's not a 4.6, find out what it is and maybe we can help.

Tom

[bingo2]

Ford had this problem on the 5.4L V8 from 97 to about 2001; then revised the design of the cylinder head adding additional metal and therefore threads to the spark plug hole.

The 4.6L issue wasn't blow out, it was carbon forming on the tip of the two piece plug and making removal very difficult, usually resulting in a broken insulator. Ford redesigned the 4.6L heads in mid 2008 and went to a smaller diameter one piect plug wto solve the problem.

[eschaider]

Originally Posted by Snakebit

Not Cobra related, but a co worker has a Ford minivan and this the second time he has had a sparkplug blow out of the head from 2 different cylinders!

I never herd of this happening, any explanation on why or how this could happen?

Basically it is caused by a Ford Engineer who determined that all you needed to hold a 14MM plug in an aluminum head was four threads of engagement. This problem has plagued Ford owners from 1997 to 2007 as the attached Ford TSB 07-15-2 indicates.

The fix is a thread repair kit from a company called Lock-N-Stitch. Much better than helicoils or timeserts.

It turns out the one page Ford Technical Service Bulletin is too big to upload. At 60 KB it exceeds Club Cobra's allowable 39K speed limit for pdf docs. Try doing a Google search and you should find it available for download.


Ed

[Snakebit]

Thanks for the info!

[Rich_ACC]

eschaider, is correct I have replaced a number of blown out plug threads fo r a number of reasons

Rich

[xlr8or]

It has been a problem for the big V10 used in the trucks as well.

[DanEC]

I have a 2003 Lightning and this was always a big issue with the blown engine guys poping spark plugs all over. My information was that it was fixed with more plug threads after 2002.

[Bobcat]

From what I could find out , the problem on the 5.4 engines is almost entirely with the 3 valve heads ..... late 2003 and on . The two valve heads don`t appear to be affected .... which is good , since that is what my F150 HAS .

[DanEC]

Lightnings all had 2-valve heads until the end in 2004 and they (and other 2V mod motors at the time) were spitting out spark plugs all over until the 2003 models with a revised head and 8 threads per spark plug came out. Probably 1 in 25 or 30 posts on the Lightning forums had to do with this problem. A common post was "First I had a rattle and then pop - blown plug. Now what?"

Don't know about the 3-valve heads. I have a Mustang GT with those now.

[Karl Bebout]

That there's some first quality, prime engineeeeering. Just about as stupid as GMs old V8 Monzas that required lifting the engine a couple inches to change a couple plugs. Stuff like this makes people develop great dislike for specific brands.