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Old 03-26-2002, 08:59 PM
300EE320 300EE320 is offline
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Join Date: Jun 2001
Location: California
Posts: 324

I'll go with you on this, after a little web research. Conventional wisdom says to remove the plugs when the engine is cold.

Help me out though. When heating metal, all the dimensions grow, including the diameter of the spark plug hole. Since aluminum expands more with heat than steel, the hole gets bigger with heat. The plug grows too, but not as much.

Well, the flip side is that the head gets thicker too. That would increase the torque needed to break the plug loose.

A final argument FOR Mikes case is that engines are assembled cold. So the clearances and torque specs must be designed accordingly.

Good, I learned something!

04 ML500
02 E430

Experience is something you don't get until just after you need it.
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