13-01-12, 01:45 PM
(12-01-12, 02:53 PM)Gnasher link Wrote: Because when heated as you say it goes soft and grips the plug threads which makes removal harder and can and does strip threads, plugs should never be removed when an engine is hot. You being an engineer will know steal and aluminium do strange things when put together one being they tend to seize if the isn't something between them e.g. plug threads have a lacquer on them for that very reason. They also have very different tensile, sheer, wear and surface finish properties as mentioned above plugs mostly seize due to being over tightened i.e. stretched threads, fitting them with crap on the threads (very common on Fazers due to owner/stealers not cleaning the plug wells before/after removing the plugs and fitting a new ones), wet or the lacquer has worn off.what an unmitigated load of bollocks this all is I'm afraid. I wouldn't have you service my lawnmower far less a bike, and my lawn mower is a push one :lol
The torque between the collapsible washer isn't what is holding the plugs in it's the the threads in the head gripping the plug threads due to any one or all of the above mentioned.
Watch out for doing any exhaust nuts up with a hot engine you may round them off as they will be soft due to the hear. A plug must be really soft when the engine is running too and goodness knows how exhaust headers don't just drip off the bike.....................