LilKingy310

Hi all,

I have a 2011 C350 at (107k miles) and just recently changed my spark plugs yesterday back to Bosch (~17k miles on the set) from the ngks I didn’t know my dad out in when we did a lot of pm at 90k. and noticed a couple had pretty dark color on the threads even though the porcelain and electrodes were dry as a bone. I know this m272 engine doesn’t have valve cover gaskets and the crankcase/cam plugs shouldn’t affect these. Is there any seals I should be looking for? Or is this just normal wear? Thanks for any and all advice!

jaimejrivera

No need to worry about that. Probably some oil got into the threads last time you changed the plugs from a small leak.

cvx5832

Your oil control rings are getting dirty. I’ve had that on two M54’s and a M272. Both went away after flushing with a cleaner (I used Liqui moly proline flush) and driving a few thousand miles. Nothing to worry about.

chassis

No combustion issues with those plugs. Maybe some oil weeping through the cam cover gasket.

LilKingy310

I did the engine flush at 100k miles which was around 10k after the plugs pictured were out in, but noticed they weren’t as responsive lately and that’s why I changed them

LilKingy310

I was happy to see the electrodes were bone dry and porcelain, but just needed to know what gasket or seal needed to get changed and where

LilKingy310

I’ll run the Bosch ones I just put in 15k miles and see if anything gets worse and change gaskets and such from there

alecmascot

Looks to me like there is aluminium in the threads and that thet have been over tightened and might strip ?

LilKingy310

they were just hand tight, nothing crazy over done to my knowledge