Spark plug stuck / cross-threaded

[warmshed]

Debateable if antiseize grease should be used on plugs.
NGK released a technical leaflet saying specifically that anti seize must not be used with new plugs with a shiny silver coating as this coating is designed to prevent
the plug from seizing. They also said the use of any lubricant would result in the plugs being torqued up to a higher value than specified with the potential for thread damage.

Yes but that obviously did not work here, my thoughts are with a little dab of antisieze he would not be in the situation he is now. Point taken about torque care should be exercised.

The NGK data states anti sieze not to be used on NEW plugs, but also states that "anti-sieze WOULD be required" on used or non plated plugs.

http://www.ngksparkplugs.com/pdf/tb-0630111antisieze.pdf

 

[Ian J Hartley]

There's a lot of speculation that the plug is cross threaded. Which I find hard to believe considering there is not much sideways play to get it off angle enough to cross thread.

It could be that when the plug was fitted last, then the stones and/or debris that surround the plug was not cleared away before fitting and has been taken in with the plug and damaged the thread in the alloy head.

 

[warmshed]

Doing up a plug on a hot engine can make it very tight, should be torqued when cold.

 

[gabriel_gs]

Unfortunately the mobile Thread Doctor guy doesn't do 'private' jobs - only through a garage.

I don't want to risk doing any (more) damage by trying to release it myself, so while it's rideable I'll get it to a pro. It's due it's 48k service soon anyway so up to Putney it goes.