91 Honda blew out spark plug

My 91 Accord blew a spark plug out of the head. The threaded end was still in place but the plug totally blew out. Anybody got any ideas why?

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Yep - I'm experienced <8^P
The aluminum head is not very forgiving of past cross-threading or overtightening. Once I lost a plug that way I started using a torque wrench and was amazed how little torque is used.
So - now what? The standard repair is to insert a helicoil in the damaged threads of the head. It sounds a bit hokey but is a solid repair that should last the life of the engine. It is normally done with the head on the engine. The catch is that the hole has to be retapped to a larger size and that produces a bunch of aluminum shavings. There are two ways of dealing with that. The controversial (and probably outdated) way is to just let the shavings fall into the cylinder and let them blow out the exhaust. In these days of catalytic converters that doesn't sound like a good idea. Instead, most people set the piston to bottom dead center on the beginning of the compression stroke. They then fill the cylinder with shaving cream and tap the head. When the dirty work is done, rotating the crank to top dead center pushes the shaving cream and shavings out. The remaining shaving cream doesn't hurt anything... assuming it didn't have silicones in it!
Expect between $100 and $200 US to have a shop do it, or to spend about $50 for a comprehensive helicoil kit for it. You might be able to find a better deal on the helicoil kit.
Mike
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snipped-for-privacy@yahoo.com wrote:

1. if you mean that the plug disintegrated and part of it is still in there, i'd have to ask what brand of plug it is so i can never buy one like yours.
2. if it simply unscrewed and blew out, that's not usually so much of a problem - they can often simply be screwed back.
3. if the head threads stripped, you can helicoil. it's a pain, but easy enough to do with the right tools.
if it's #1, how much of the plug is still in there? if it's just the metal outer, you can unscrew it with an easy-out and simply replace the plug. if it left part of the core in there, the danger is the core dropping into the cylinder. if that happens, you'll have to remove the head. if you can post a pic of the plug remnant, it will help us advise better. tinypic.com is free.
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