I am replacing the spark plugs.
7 came out without a glitch, but one (3rd from the front passenger side) is very hard to turn.

It broke loose, but it seems the force I need to move it is much higher.
Having learned from past experiences, I did not attempt to turn it any further then probably 5 degrees, and it is soaking in some penetration fluid right now.

I presumed the plugs were changed at 50k by the previous owner, but the other 7 seem long long overdue, so they have been there for a long time. They look pretty bad.

Any specific advice on preventing disasters?

Thanks,

Eric

 

I think you've done correctly by dropping in the fluid and let it sit a bit. You say it broke loose, so I would work the plug as far out as you can and back in a number of times to try to work the fluid down the threads and see if that helps it rotate easier.
It does sound like there is some build up on the end of the plug creating the hard extraction. How do the others look?

 

I would suggest a dab of anti-sieze and using a torque wrench when re-installing to help prevent this next time.

 

If it does start to turn relatively smooth after penetrant and then get hard to turn again, stop! Spray down with penetrant and let soak again for an hour. When the plug starts to get hard to turn, that's when the plug starts to pull the threads out and of course the damage continues. As long as the metals are cold and turns easily, there won't be as much damage. It may take some time. Get a spark plug rethreader, not a tap.

 

I asked here, cause the internet is full of advice, but it hard to judge genuine from BS.
Better safe from some x308 expert than sorry.

Last night I found a Ford technical notice on stuck plugs in their short threaded alloy heads, and they advised to soak with carburetor cleaner, as it penetrates easier, and cleans the stuff off.

So I did overnight, and with indeed some careful backward and forward wiggling it came out rather easily this early morning.
Most important, no thread damage.

Now will need to find the high temperature anti-seize here, will follow up on your advice for sure.

Thanks again!

E.

 

That's good news Eric....

 

Glad you found the TSB. I've posted it before.

One more reason for just using platinum plugs and changing
more often than the iridiums.

 

That is also a way to put the discussion between Platinum and Iridium's to an end .

Anyway, considering the severely reduced, burnt and dirty ends, it is amazing how smooth the car was still running.
I can only blame myself for not having replaced them when I bought the car.
Going over the previous owner's service records an other time, I might check some more of what was "done" before ...

 

Don't use anti sieze on NGK plugs or any plug with a coating on the threads, this can be the cause of plugs breaking or being difficult to remove:

http://www.jagrepair.com/images/Auto...1antisieze.pdf

"Applying anti-seize to the threads of spark plugs that have a metal plating allows the installer to mistakenly over-tighten the spark plug in the cylinder head; This stretches and fatigues the threads of the spark plugs, causing a much higher probability that the plug will break during installation or in some
cases upon removal."

"All NGK Spark Plugs are manufactured with a special trivalent Zinc-chromate shell plating that is designed to prevent both corrosion and seizure to the cylinder head; Thus eliminating the need for any thread compounds or lubricants."

Vector

 

Vector,

Thanks for the head-up, I had read several of the (long and heated) threads before.

The plugs removed were platinum NGK, coated, and installed without anti-seize.
The one stuck should have damaged the thread for sure without the actions taken.

I will give the anti-seize a try, and install them with the angle-method, so the torque issue and consequent over-tightening will not occur.
I did so on my Ducati motorbikes, and never had a problem.

Case of "to each its own" I guess .