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removing spark plug in aluminum cyl,head

I am not sure if it is better to remove them when the engine is hot or cold?
<br/> The reason I am asking is I am doing A tune up and had some problem with the replacing the plugs and one is really in there and I am afraid of the stuck plug braking or striping out.
<br/> So what is the best way to approach the problem.I have the big tools to relay put some torque on it.I feel some fineness is in order.Thanks for any wisdom.


  • edited December 2008
    There were two recent posts (one just ended yesterday)about this situation "Stuck Plug needs a Bailout" and another about a stuck plug,read them and post back.
  • edited December 2008
    I prefer doing them cold but to each his own. The way I look at is that the steel shank of the spark plug has contracted as much as it's going to.

    When loosening plugs never instantly apply a lot of grunt when breaking them loose.
    Try it gingerly at first and if it appears to be a bit stubborn try to bump it back the other way; tightening it a bit. Seesaw it back and forth a little.

    As long as it persists in not turning freely I would advise that you keep seesawing it until it does. Normally this will bring them out without destroying the threads.

    When reinstalling plugs I never use a socket. I always use an 8" long piece of stiff vacuum hose that has an inside diameter just big enough to fit snugly on the tip of spark plug. This prevents any cross-threading. Use some anti-seize on the threads also. Hope that helps.
  • edited December 2008
    i also blow out/off as much crud around the sparkplug as possible PRIOR to removal, so to eliminate junk falling down into the cylinder.
  • edited December 2008
    Never remove spark plugs when an engine is hot and the aluminum is soft.
  • edited December 2008
    After you break it loose, spray some penetrating oil on the base of the plug (PB Blaster works good) and work the plug back and forth so the oil can lubricate the threads and minimize any thread damage..Since aluminum expands MUCH more than steel when hot, I would not be afraid to break it loose when hot, but remember to lube the threads on the way out. If you feel resistance coming out, screw it back in and try again..
  • edited December 2008
    The melting point of aluminum is over 1200 degrees Fahrenheit. If the metal is hot enough to be soft, I'm pretty sure changing the spark plugs is going to be a complete waste of time.
  • edited December 2008
    The Haynes manual for the 2002 GMC Sierra says to allow the engine to cool completely before removing the plugs. I guess you can then install the new ones at any temperature...
  • edited December 2008
  • edited December 2008
    So what? We're not talking about the cylinder head melting. Aluminum is a soft metal to begin with. Heated to operating temperature only makes it softer. I can give you an aluminum bar that you cannot bend at room temperature. Then heat to 500 deg F, and you can tie a knot in it.

    Removing spark plugs from a warmed-up engine with aluminum heads will INCREASE the chances of stripping the threads.
  • edited December 2008
    Champion's Been Around. Take A Look At Their Installation Tips.

    Click this:
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