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2011 E350 OM642.852 Seized Engine

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Old Feb 1, 2025 | 11:30 AM
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W212 E350 Sport
2011 E350 OM642.852 Seized Engine

Hi all
I've recently purchased a CoPart special and the vehicle was supplied without any keys - I know, I know, you can expect issues here!!





Naively I thought it'd be a case of getting some new keys coded and all would be well - no such luck!!
Having got keys sorted, engine would not turn over. Pulled starter motor and tested this faulty so replaced. New starter motor in, but still no joy.
Tried to turn engine over on crank and absolutely solid - worst case scenarios now going through head!!
I've pulled the injectors today, and they look new - but cylinder 6 has corrosion on it.
Also looked at the oil filter and there's an amount of metal swarf in there :-(
Any advice on whether this is a complete engine rebuild or might I get away with another course of action?
Thanks in advance
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Old Feb 1, 2025 | 11:38 AM
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19 GLA45, 86 560SL, former: 14 E550 4Matic, 09 E350 4Matic, 83 240D manual, 78 450SLC, 81 500SLC
At this point you need to look at the internals however you can. You can pull the oil pan and poke around a certain amount from the bottom. You can stick a boroscope in the injector or glowplug holes and check out the top end from there. After that, you would need to start pulling pieces of the engine until you find the culprit. At some point you will have worked yourself into a rebuild regardless of the problem just due to how many parts you have removed.

Good Luck!
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Old Feb 1, 2025 | 11:40 AM
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19 GLA45, 86 560SL, former: 14 E550 4Matic, 09 E350 4Matic, 83 240D manual, 78 450SLC, 81 500SLC
Another thing.. If corrosion in a cylinder is what has the engine seized, squirting some penetrating oil of some kind into the cylinders and letting it soak, then cranking on the crank nut manually might bust it free. But poke around visually and see what you can see first...
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Old Feb 1, 2025 | 12:42 PM
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W212 E350 Sport
Thanks for the replies @ChuangTzu - was thinking I might try putting some acetone / ATF 50/50 mix into the suspect cylinder to see if this frees things off.

Am I right in thinking that a busted conrod / bearing would have hit the injector and damaged the tip?

Thanks again!
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Old Feb 1, 2025 | 02:05 PM
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Super helpful - thanks 🤔
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Old Feb 2, 2025 | 12:52 AM
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19 GLA45, 86 560SL, former: 14 E550 4Matic, 09 E350 4Matic, 83 240D manual, 78 450SLC, 81 500SLC
I don't know why I thought that was a diesel the first time I read it. You might be right about the injector crashing, but the valves and piston head would also likely show evidence of this. Stick a boroscope in there and look for evidence of the crash.
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Old Feb 2, 2025 | 04:18 AM
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Yep it is a diesel, boroscope it is!
Thanks
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Old Feb 2, 2025 | 03:07 PM
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19 GLA45, 86 560SL, former: 14 E550 4Matic, 09 E350 4Matic, 83 240D manual, 78 450SLC, 81 500SLC
Originally Posted by ChrisMOwen
Yep it is a diesel, boroscope it is!
Thanks
Oh right, that's why, it's in the thread title!
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