How much torque can be applied to open a seized Spark Plug?

[bj70bc]

acetone kerosene and atf and Heat works wonders, and smells better than any penetrating oil.
and as for the original question...easy, 99.999% percent of your plugs shear strength

 

[Marvelicious]

It’s also an old motor and who knows how many jabrones have been in there either. If you followed the manufactures 30k spark plug interval ( unlikely ) at 200k or what ever it’s likely many times. Hopefully but I doubt it there are too many variables at stake here to assume anything other than why are the plugs stuck? Have the threads been packed with anti-seize or over tightened, loose, did those cylinders get hot the list goes on and on. If proper procedures were followed and torque specs used I doubt we would be having this conversation, it’s not like we’re talking about fords here it’s old Toyota for Christ sake. I’d put money on its not tight for absolutely no reason. Follow torque specs don’t over tighten, use a good torque wrench and don’t use anti-seize. I’ve done countless spark plugs on you name a motor, I’ve done one . Some times they come out grumpy from factory but who knows over thousands ef engines built something didn’t go wonky in production. I did a 2022 Honda odyssey the other day 2 cylinders spark plugs were far tighter than the other 4….. guess who didn’t use anti-seize I used a drop of light lube on the first 2 threads and a 700$ Snap-on 1/4” torque wrench. It’s not like rookie techs using a 18” ratchet and “feel” with a side of anti-seize the toughest to get out plugs have always without a question been anti-seized. It’s fine for iron on iron conical plugs on old school rigs. But on Asain vehicles it makes no since. Buy good plugs use a good torque wrench. Period.

I've removed stuck plugs as well, just never any of the plugs I installed myself.

I don't doubt you are correct in that, if everything is done "correctly", anti-seize is unnecessary on spark plug threads. Since I live in a world where things don't always happen according to what would be theoretically correct, using a bit of an inexpensive product I already keep on hand feels like cheap insurance. Unnecessary under ideal circumstances isn't the same as imprudent. I'd be willing to bet that over-torque is the problem in the most stuck plug cases (certain s***-show Fords excepted), and I'd bet that happens completely irrespective of anti-seize, generally at the hands of someone who may have never used a torque wrench.

The only potential downside I'm seeing anyone to using anti-seize is the potential to over-torque plugs. Based on all available evidence (see first sentence) I'm not doing that, so I'm going to continue. A lot has been written about using reduced torque values with lubricated fasteners, and while my torque wrench didn't come off the tool truck with the super expensive logo, it seems to work.

Anyway, I've said my piece. I'm sure you'll never have to remove any stuck plugs I have installed.

 

[jonheld]

Wow. I didn't mean to tie anyone's panties in a knot over such a simple silly little thing.
If you don't want to add a little dab of anti-seize to the spark plug threads, then please, by all means, DON'T DO IT.
No one is telling anyone that it MUST be done, or that it is required by any manufacturer. That is NOT what was said.

I'm an old and crusty motherf*cker and I will continue to do what I consider to be "best practices" on MY vehicle for MY use case.
Anyone is more than entitled to disagree. But please keep in mind that unless you come up with a "best practice" that I've routinely done for the last 35 years that will cause untold woe and strife, or cost millions of dollars and countless lives, I really don't give a sh*t.

 

[MissahPapaJ]

Wow. I didn't mean to tie anyone's panties in a knot over such a simple silly little thing.
If you don't want to add a little dab of anti-seize to the spark plug threads, then please, by all means, DON'T DO IT.
No one is telling anyone that it MUST be done, or that it is required by any manufacturer. That is NOT what was said.

I'm an old and crusty motherf*cker and I will continue to do what I consider to be "best practices" on MY vehicle for MY use case.
Anyone is more than entitled to disagree. But please keep in mind that unless you come up with a "best practice" that I've routinely done for the last 35 years that will cause untold woe and strife, or cost millions of dollars and countless lives, I really don't give a sh*t.

I guess next time I pull finger tight plugs out of a first time ever spark plug service interval I should reinstall the new plugs with high temp loc-tite.

 

[mudgudgeon]

I will definitely order KROIL for future use

A good alternative available in Australia is Würth Rost Off penetrating oil

 

[mudgudgeon]

The modern spark plugs are electroplated and give a dissimilar metals a buffer. Antiseize is for rookies and old school iron heads with non electroplated iron plug threads.

After fighting with most of the plugs in my F150 5.4 triton, (IFYKYK), you can be sure as sh¡t never sieze went on all the plugs.
Rookie status, electro plate, and alloy heads be damned!

 

[MissahPapaJ]

After fighting with most of the plugs in my F150 5.4 triton, (IFYKYK), you can be sure as sh¡t never sieze went on all the plugs.
Rookie status, electro plate, and alloy heads be damned!

That’s cool the problem lies in the design and how far the arch style electrode go’s into the bore and the tolerances and carbon build up. I just started changing them at 50k not 100k you break a couple of plug body’s and you may as well have just changed them early when it comes to extraction labor.