Help - metal found in oil pan M189 engine...

[scoot]

I'm trying to bring my 1965 W112 300SE lang back to life.  Yesterday I changed the oil and ran into concerns.

First, there was a piece of metal in the drain pan.  I know this isn't a good sign.  I'm wondering if anyone can identify what this piece of metal might be.  The pictures next to a penny show it as I found it (except covered in oil).  The other two pictures are after I spread it open some revealing what looks like groves.  I thought that might mean something to someone.

After a little more searching around I found a third piece.  (the first piece broke into two pieces)  I'm pretty sure it's a nut, probably M6.  

Suggestions?  What do I look for?  Where do I look for a missing nut?

[mdsalemi]

Wild guess here, Scott--connecting rod nuts?

Regardless, if the engine was "running" albeit even a bit rough before you shut it down to change the oil, and you pulled THOSE things out of the oil pan, seems to me like you rebuild/send for rebuild that engine. If whatever those nuts were meant to hold lets loose when running you could easily destroy the engine by throwing a rod right through the wall of the engine, rendering it 100% useless. Consider yourself lucky to discover these metal pieces now as opposed to when the engine is running...

[scoot]

Wild guess here, Scott--connecting rod nuts?

Regardless, if the engine was "running" albeit even a bit rough before you shut it down to change the oil, and you pulled THOSE things out of the oil pan, seems to me like you rebuild/send for rebuild that engine. If whatever those nuts were meant to hold lets loose when running you could easily destroy the engine by throwing a rod right through the wall of the engine, rendering it 100% useless. Consider yourself lucky to discover these metal pieces now as opposed to when the engine is running...

Engine hasn't been running in 10 to 15 years, at least two owners ago.  Rebuild isn't an option - $20,000 to $30,000 - which is cost prohibitive to me.   I'm in the process of acquiring a rusting car with an M130 engine that was rebuilt 30 k miles ago in case a transplant is necessary.   Seems like a reasonable swap that hopefully won't  be too difficult...   Or am I fooling myself...

[ja17]

Most likely some parts someone dropped down the chain gallery. Looks like the nut was mauled by the chain sprocket. The danger is any damage caused to the chain sprocket on the crankshaft.

[scoot]

Most likely some parts someone dropped down the chain gallery. Looks like the nut was mauled by the chain sprocket. The danger is any damage caused to the chain sprocket on the crankshaft.

Thanks Joe -
Are you suggesting that the valve cover was off and a nut fell in, or that a nut came off of something internal and went down the chain pathway?   The engine cranks just fine and I'm hoping to start it within a month.   Is there something I should look for first, or is what damage is done done?
Scott

[Fintail]

you can see a lot with a scope camera after draniing oil

[scoot]

Excellent suggestion.  Thanks.