2012 C 250 Oil Filter O-Rings
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2012 C 250 Oil Filter O-Rings
Have done my own oil changes for years but just noticed 1 o-ring was missing when pulling the filter out of the housing. The bottom most smaller diameter o-ring was not in place. I spent a lot of time looking into the filter housing but no small o-ring to be found. I always replace the 3 rings so it wasn't something I overlooked last change. I went ahead and properly finished the oil change and started the engine with no ill effects. Where the heck did that o-ring go? If it did drop into the bottom of the housing is that going to be a problem down the road? I am a bit concerned. Has this happened to anyone else when changing filters?
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From: Northeast
2012 S350 Bluetec, 2014 GLK250 Bluetec, 2026 E350 4Matic
Most likely if it fell down in the engine, it will harmlessly get caught in the oil pickup screen. Also, it's soft enough that it would just turn to pulp if it went through the moving parts and harmlessly end up in the oil filter. I think you'll be fine.
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In my mind that’s what I was hoping for. I am not familiar how the oil returns to the oil sump on these engines. So if the o-ring has a clear open path to drop into the sump I can see it sitting at the oil pickup screen and not getting farther. My concern was it could somehow get sucked into and block an oil galley/passage. Like you also mentioned the ring gets chewed up by the crankshaft or other rotating internals, problem solved. Thanks for your insight.
Last edited by Pepperschatz; Apr 16, 2025 at 12:41 PM.
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I did not find anything in the oil draining that was o-ring related. I use an oil drain caddy that collects probably 15 quarts in the base so if there was a ring it would be sitting in the bottom and really hard to recover.
