bl817

Working on a 2010 GT manual, 113k mileage. owner wants to replace plugs. I tried 1 with as much force as I was comfortable with and it wouldn't budge. I know these are the updated plugs so I'm not worried about that. I am worried about messing up the threads in the aluminum head tho. not sure if the plugs have been changed or not. should they be this difficult to remove? do they need soaked in PB Blaster or something? cold engine? can I apply more force I.E. breaker bar? I was using a 3/8" ratchet with extension and 14mm socket. never had plugs give me this much problem, even the ones in my 05 GT lol, thanks in advance.

Derf00

Are you trying to loosen them while the engine is at room temp or with the engine still warm?

At room temp it can be difficult because you have dissimilar metals. Aluminum heads will expand faster than the plug so, start her up...let her get warm (not super hot) , then try again.

I wouldn't worry to much about breaking any because like you have already pointed out, they have the newer plug design in them. At the most you'll break some porcelain but the plug can still be removed.

bl817

car was warmish, put it on the ramps and changed the oil first, then tired the plugs. when I get the car back, ill make sure its up to temp or close. ive read ppl using impacts to remove plugs, im just not comfortable with that. im also not comfortable needing a breaker bar tho as well lol. thanks!

08'MustangDude

It may require the motor to be hot to get them out, rather than torched out.
I took a Mazda 4cyl into a shop, one of the plugs would not come out, and they
tried to torch it out, and cracked the piston in that cylinder. If I would have
known they were gong to do that, I would have ran it to hot, then tried to pull
them out. They did replace the motor, it was their fault.

If they were NEVER replaced, they can be in there good...

Or the plugs were replaced, and they did not torque them correctly, so they're in
too tight. I use a very VERY thin coat of aluminum anti-seize on the threads close
to the seat, but not on the seat, and torque to 25 ft-lbs. I am getting 27 MPG
with NGK G-Force plugs, highway only. I was getting like 24/25 before I changed
them last week. 93 Octane K&N Firm Shift Tune.

Though, most all plug MFRs say not to use anti-seize, some say if you do, reduce
torque value by 15-20%. Some also say to use anti-seize if you are reinstalling spark plugs...