strange spark plug

[geezerstiva]

ok i went to replace the plugs in my 89 L and found out one of them is messed up. bad. it looks like somebody cross threaded it in there and now its crooked. cant get a wrench on it. my question is, is there any way to get it out without messing up the hole? or am i pretty much resigned to a new head?

ps. i know if its cross threaded there's not much hope of fixing it, other than maybe one of those heli coil things. maybe a shop could have put a heli coil in there and got it crooked?

[Festy46]

Break the plug off down to the steel base and then try a regular socket with an extension instead of the spark plug socket. If you still can't get on it, look at your socket and see if you could grind off any of the socket to make it fit.

I doubt if a shop screwed it up. More likely is one of these "first time" Festiva mechanics that messed it up. I've bought some partially finished "project cars" and you wouldn't believe the stupid stuff some people do.

[jglutz]

^^good advise for the removal
Is the head shot?...NO!
Are the threads shot? Possibly....you won't know until the old one is out...be careful if you use a new plug to determine this...you don't want to get it sideways too.

There are tools available for just a repair...threaded insert and special tap....available at any parts store....just follow the instructions weel or better yet find some one who has one. Taps cost ±$20...pack of 3 inserts ±$7½. If you borrow a tap....the inserts must be of the same brand as the tap.

Most...including me...will say it is best to remove the head to put the insert in...however...shops install inserts without pulling the head all the time and I've never heard of any fall out. Go for it.

[Axlander9289]

I've heard that a helicoil is actually stronger than just the tapped head. Some hotrodders will heilicoil all the spark plug holes so they can run super high compression without worrying about blowing spark plugs through the hood.

[jglutz]

I've heard that a helicoil is actually stronger than just the tapped head. Some hotrodders will heilicoil all the spark plug holes so they can run super high compression without worrying about blowing spark plugs through the hood.

News to me....I could layout a whole bunch of ±'s about thread strengths....however, there is one flaw in the logic....any time you add an additional joint (the one between the head and the helicoil) you add a potential failure...thread or leak...specifically where the plug flange seats.

The good inserts...I think KD brand...have a collar at the top that is peened into the head with a special punch to provide a nice flat surface for the plug to seat on.

[25Horseplay]

I have a tap that is made just for spark plug threads. Works pretty good too!

[jglutz]

For all those wodering what the heck I'm / we're talking about.....

The first pict is the threaded insert tool and an insert

Second pict....other tools laying in the drawer....a die...a tap ...and a chase....handy stuff.....



The thread pitch for a standard sparke plug is 1.25mm...that's 0.060" per turn or 0.090" per 1½ turns

[geezerstiva]

so... it is possible that the threads are still ok? even with the plug in there sideways?

[jglutz]

so... it is possible that the threads are still ok? even with the plug in there sideways?

It's very possible that SOME of thte threads ar still ok...how many is a better question...in any case the transition firm bad to got threads will be tricky...be sure if the existing plug comes out....don't force a new one im.