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What (if anything) do the pictures of my spark plugs, tell me about the condition of my engine?

544 Views 5 Replies 3 Participants Last post by  kamilmarshal96
Hi all,
Just serviced my beloved 2013 R56 JCW Mini.
It has 40, 446 miles 'on the clock' and the oil is changed every 12 months/5000 miles.
These Champion 12ZR-6SPP2-1 were dealer fitted in September 2017 at 19,602 miles.
Do these plugs give any indication, as to the condition of the engine?
I'm absolutely no expert, so any advice from you knowledgeable members, is greatly appreciated.
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  • Light tan: Great fuel mixture and air-fuel ratio. That means nothing goes wrong, and your engine is operating well.
  • Black or dark brown: The engine probably runs too rich. These spark plugs will feel a bit dingy under your hands.
  • Oily and black: Fouled oils. In that case, continue to inspect the piston rings or valves. They are the most likely culprits.
  • No colors/light grey/white: The most worrying condition of all – since they clearly imply lean-running engines.
  • Worn/eroded center electrodes: Symptoms of a plug long past its peak.
  • Flattened or broken electrodes: You probably have set up inappropriate/wrong spark plugs. Spark plugs too long may cause engine damage, while short ones result in spark plug foulings and terrible gas mileage.
  • Blisters on insulator noses/white carbon deposits/melted electrodes: Hotter plugs than required.
  • Wet plugs: Check whether your engine is flooded.

i read those plugs as lean running , when we rolling road these engines we always aim at choco brown darker the brown the richer they are under load, these engine need slightly rich fueling to stay together when nailed hard, the only thin that cools the combustion process is the fuel at that point , lean the pressure and heat builds up so much and will hole a piston crack a valve even impact crank on point of melt down by pre ignition if caused by timing chain way out, yours look to be grey and have black carbon where not in the heat ball as such ,,
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pull the upstream 02 sensor out and have a look at its colour healthy is choco brown tan
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Thanks for taking the time to reply, Mike.
pull the upstream 02 sensor out and have a look at its colour healthy is choco brown tan
Will, do. Thanks. :) (y)
The condition of spark plugs can provide some insights into the overall condition of an engine, but it is not a definitive indicator. Spark plugs can offer clues about combustion efficiency, fuel mixture, and general engine health. However, they should not be solely relied upon to assess the engine's condition.
In your case, the Champion 12ZR-6SPP2-1 spark plugs were fitted by the dealer in September 2017 when your Mini had 19,602 miles on the odometer. Given that you have driven an additional 20,844 miles since then, it is reasonable to assume that the plugs have experienced wear and deposits over that period.
During a routine service, the spark plugs should have been inspected by the technician. They would have checked for any signs of fouling, such as excessive carbon deposits, oil residue, or unusual wear. If the plugs were in poor condition, it could indicate issues with combustion or other engine problems.
However, without further information about the condition of the spark plugs after the recent service, it is difficult to make an accurate assessment. It's best to consult with your mechanic or service technician who performed the service. They will have firsthand knowledge of the condition of the plugs and can provide a more informed opinion about the overall health of your engine.
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