Any good tips on getting a seized spark plug out? I've had a weird misfire lately, and figured I'd change the plugs to start with. Well, all came out fine except #3, which feels like it's about ready to twist off. I haven't taken it that far yet, and don't want to.

Would an impact wrench help or hurt?

Tried it with the engine warm and cold. Sprayed PB Blaster around it. Tried working it back and forth (loosen, tighten). Still no go.

The plug isn't broken off yet, but I feel if I turn much harder, it will.

Any ideas would be appreciated.

I had this happen to me before on a Honda D-Series engine.
How I got it out:

The spark plug was still fine and burned fuel, so I sprayed PB blaster around the plug but into the "well" and let the engine run for about 3 to 4 minutes, long enough to warm the head but not enough to get hot.

I then use my torque ratchet set to 100 ft lbs of torque and tightened it HALF A REVOLUTION/HALF WAY FROM START then switched it back loosen and out came the spark plug.

DO NOT USE IMPACT OR ANY AIR TOOLS!!!!
DOING SO YOU RISK CROSS THREADING WHERE THAT PLUG GOES AND YOU WILL PRETTY MUCH NEED A NEW HEAD!

Soaking with penetrating fluid and working it back and forth like you have been is the best way I can think of.
I've heard a 50/50 mix of brake and AT fluid works good.
I've personally never seen a plug break off but have seen them take the threads out of the head. Doesn't mean the head is garbage you can just repair the plug hole. Should take the head off if doing more then chasing threads so metal shavings won't end up in the motor. Coat the threads of the plugs with anti-seize when you install them.

Post deleted by haztoys

I think you may be more high then I am right now sir.

Sigh...?????????? .. OK ..? .. Got it .. Good luck on your travels my friend ..

Have a good day .............. <img src="/forums/images/graemlins/confused.gif" alt="" />....

It was just a joke, I didn't mean any offense.

Ok, thanks guys. Just wanted to be sure there wasn't any tips that I was missing. I'll keep working at it. Truck isn't being driven right now anyway.

Well, after a week of tinkering with it, I finally got it out today. Got a new plug in, and the thing is running correctly again! Yeah!

That is great news.