iamhedgecore

just picked up a 2006 CS with 117k on the clock, it had a knock or tap sound coming out of the right head.... pulled the motor, and there are no obvious signs of damage, clean oil filter, heads looked good as far as i could tell. when i pulled the spark plugs, #6 was very fouled, and built up; see pic. Any ideas what could be the problem... i thought it could be a stuck lifter, but that wouldn't explain the oil in 6.

Boiler Inspector

No pic.

iamhedgecore

https://drive.google.com/file/d/1Ams...ew?usp=sharing

Boiler Inspector

I would get a borescope and inspect the cylinder walls in #6.

iamhedgecore

good idea, are you thinking bore scoring?

Boiler Inspector

Might be bore scoring; might be bad/broken piston rings. Something is letting oil into the combustion chamber.

iamhedgecore

ordered a scope, cheaper than i thought! hopefully can find out monday.

txbdan

Watch The Knowledge Gruppe Flat 6 Innovations youtube series on bore scoring. One episode describes the symptoms and unfortunately yours sound similar. He even says it sort of sounds like a bad lifter, but these cars have very robust liftters and more often than not its bore scoring. He posts a sound clip as well.

He also describes how to bore scope it and what to look for.

NuttyProfessor

As mentioned, watch Jake Raby's series on Bore Scoring on YouTube. Very informative.

https://www.youtube.com/playlist?lis...iZKhfNjeTXaRkn