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Premium Member 2012 SLK55 AMG
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Discussion Starter #1
Just had a quote for a service including a spark plug change from an Indy and it came back only 4 plugs on the quote. I questioned this, saying i would expect 16, 2 per cylinder as per the R171 SLK55. They've now come back to me saying it was 4 per bank, so 8 total just 1 per cylinder.

Could someone who has had a spark plug change done please confirm if it's 16 or 8 on this model. Gut feeling is it will be 16. :smile:

Thanks
Col
 

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106 Posts
It's 8.

Think of it?

4 valves per cylinder makes ideal plug place in "center" of valves, which is center of cylinder.

on R171, 3 valves per cylinder makes ideal plug place "surrounding" exhaust valve, so two plugs per cylinder there, on cylinder edges.

EDIT: this is not Mercedes specific. Most often 3 valves per cylinder machines have two edge plugs.
 

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Premium Member 1999 SLK 5.4 M113
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M113 V8 engine has 16 spark plugs.

but I believe you are talking about a different engine.
 

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Super Moderator UK SLK 55 AMG 2007
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27,257 Posts
Hmm!

Maybe you only truly need 4 because you have been driving sedately on four cylinders.




Yeah, right!
 

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Premium Member 2012 SLK55 AMG
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Discussion Starter #9
Yes, thanks for all your knowledgeable replies. Had the car serviced today and can confirm 8 plugs on the ticket!
People ask me all the time what are the improvements in the R172 55 compared to the R171? Well here’s another plus point for the list! They’re cheaper in the spark plug department too! “Less is more!” :surprise::laugh:
 
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