This is a general question, I'm looking for all sorts of causes at the moment - but what causes spark plugs to get coated in smooth, black, dry soot?
Cheers, James
What causes sooty plugs?
Jul 08, 2005
7 Replies
Improper combustion due to over-rich mixture.
Ta, G.
Just checking - that's /solely/ due to over-rich mix? A weak spark or wrong-octane fuel wouldn't cause it?
Cheers,
formatting link
Yes. Ta.
Soot.
HTH.
Peter
LOL - glad to be of service. :-)
Peter
Yes they would do that too. A rich mixture simply means there's too much fuel to be burnt in the cycle, for whatever reason.
Others have given some reasons but in addition too short a plug can cause this. If the plug doesn't reach far enough into the combustion chamber it runs too cool and can get sooted.
Rob Graham
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