Super Tight Plugs!

[stevec5000]

I just changed the plugs in my 04 V-6 with 138k miles and they were so tight that I had to use an impact wrench to get them loose! Does anyone know what would cause them to get so tight? They weren't the original plugs so they must have been replaced at least once before. Usually just using a small 3/8" drive ratchet handle is sufficient to get them tight enough, I've never heard of anyone using an impact wrench to tighten plugs. There was no problem with the threads though, once I got them loose they turned out easily.
BTW, my mileage has gone up 2 MPG, from 21.5 to 23.5 after replacing the plugs.

 

[Natey]

Make sure you use dielectric grease when putting new plugs in. Otherwise they can seize up in the block and ugly things can happen.

Sounds like they may have kinda corroded in there on ya.

 

[stevec5000]

Make sure you use dielectric grease when putting new plugs in. Otherwise they can seize up in the block and ugly things can happen.

Sounds like they may have kinda corroded in there on ya.

Nope, no corrosion at all. Just super tightness. Of course I did use anti-seize on the new plugs when putting them in.

 

[BucknutBob]

Oh, the joys of aluminum heads! After they heat up and cool down a few times, they can get a death grip on plugs. Best to try after the engine sits overnight, so the metal can contract some. Keep putting the slippery stuff on the threads, too.

IMPORTANT EDIT: I totally forgot about this--an "old timer" buddy gave me this tip, and I saw it in action and was quite sold--use a small amount of gasoline dripped onto the plug with a funnel--fantastic thread loosener! Forget all the fancy sprays--this dirt-simple trick works.

 

[NorCalBorn]

Another trick is use a keyboard cleaner spray bottle upside down and spray down the plug base. Do this a couple of times across the time span of about 4-5hours and let it sit overnight. *DO NOT ATTEMPT TO REMOVE OR EVEN PUT A TOOL ON THEM WHILE FROZEN COLD, THEY SHATTER*ALSO DON'T BREATHE ANY VAPORS OR OFFGAS*.

The cold cycling as opposed to the heat cycling will cause the two metals to shrink at differing rates breaking loose the bind.

 

[stevec5000]

Oh, the joys of aluminum heads! After they heat up and cool down a few times, they can get a death grip on plugs. Best to try after the engine sits overnight, so the metal can contract some. .

No, they don't normally get tighter. I never had any do that before. They usually get looser after a while.

 

[BucknutBob]

No, they don't normally get tighter. I never had any do that before. They usually get looser after a while.

I've been working on cars for a few decades now, and that would be a first in my experience. I've had to break them loose numerous times. Oh well--good luck with 'em.

 

[fourwd1]

Just about any manual will tell you to use some anti-seize on the plug threads.
Works wonders.

 

[stevec5000]

Just about any manual will tell you to use some anti-seize on the plug threads.
Works wonders.

Anti-seize won't make any difference in how tight they are and since they weren't seized it doesn't make any difference there either. Might keep them from getting seized sometime in the future so I guess it wouldn't hurt.

 

[stevec5000]

I totally forgot about this--an "old timer" buddy gave me this tip, and I saw it in action and was quite sold--use a small amount of gasoline dripped onto the plug with a funnel--fantastic thread loosener! Forget all the fancy sprays--this dirt-simple trick works.

Of course pouring gas on the plugs is not going to do anything at all since there is a seal.
It's amazing how many old wives tales there are with silly nonsense like this that people keep repeating.

 

[Atlanta_man]

On my V8 at first change (100K mi) they were all pretty loose. One was loose enough that it was allowing some blow-by based on the color of the coil pack connection rubber.

Bet yours were not factory installed but replaced by a strong mechanic along the way.

 

[Ron Helmuth]

The MR2 had super tight plugs like Original Poster described- we started the car up and let it run 20 minutes or so, then the plugs could be coaxed out like butter.

more than one way to skin that cat