Alpha Gen 2 Sterndrive Issue

[ceeg52]

Pulled the boat for the season and heard some noise and confirmed I needed a new gimbal bearing. It's been 2 years since I replaced the water impeller so I purchased the parts (I've changed the impeller over the years so I know what I'm doing). No water in lube oil when drained. It was not milky and looked good. However, when I separated the upper and lower unit I noticed what looked to be rocks sitting on top and the around the impeller housing (See photos). It is not pieces of the impeller. That was actually in good shape. It it even possible for rocks to get in this area or is it some type of seal. I pressure tested the upper and lower unit prior to separating the unit and it held 15 PSI for hours.. Based on the photos is there any thing I should be concerned about. Specifically how these rocks/debris got in that area of the outdrive.
Thank you in advance for your help!

 

[Fun Times]

Possibly this could be portions of something out of the exhaust system.
Do the pieces seem really hard or some flex to them?

If some flexing, maybe hardened rubber type material from say a Y-pipe exhaust water flappers or if no flex, exhaust metal type material starting to deteriorate such as an exhaust elbow, etc..

Is the filler wall still in place normally situated in the upper housing? Item number 7,

https://www.mercruiserparts.com/bam/subassembly/30862/2686/120

 

[ceeg52]

Possibly this could be portions of something out of the exhaust system.
Do the pieces seem really hard or some flex to them?

If some flexing, maybe hardened rubber type material from say a Y-pipe exhaust water flappers or if no flex, exhaust metal type material starting to deteriorate such as an exhaust elbow, etc..

Is the filler wall still in place normally situated in the upper housing? Item number 7,

https://www.mercruiserparts.com/bam/subassembly/30862/2686/120

Thanks for the response. The material I collected looks like chunks of rust from the manifold risers.

 

[stresspoint]

+ 1 on the chunks of rust , pull the manifolds and rises for inspection , looks like you may have saved yourself from a future engine problem from a rusted exhaust.

 

[Bt Doctur]

The tips of the elbow are disintegrating and dropping in the exaust

 

[nola mike]

Throw a magnet on them