Marine engine mystery - cooling system debris in oil pan

[ledslinger]

Helped a buddy pull a Holman-Moody 302 Ford out of his 1970 Donzi sweet 16 yesterday. He had already pulled the heads and manifolds, so we pulled the block assembly and took it apart. In the oil pan was about a half a cup of apparent cooling system debris, iron oxide chunks looking like corroded iron bits from water jackets.

Can't figure out how cooling system debris could make it into the oil pan when there isn't any signs of water jacket damage and no water in pan. It kind of looked like the cooling system debris hadn't been there long since it didn't look like any had made it to the oil pickup screen. But since the cast aluminum pan has baffles, the debris may not have had a route to the pickup anyway.

Looking for solutions to this mystery. The motor looks like it has never been out or apart. Thanks

 

[supton]

Did you pull valve covers off? I'm wondering if debris fell in from the oil fill tube, or off the bottomside of the valve covers or any sheetmetal that might have seen ambient air over the years. My thinking being, if the engine may have sat for years (and years) without running, perhaps any spot exposed to air may have rusted and eventually flaked off.

 

[ledslinger]

Did you pull valve covers off? I'm wondering if debris fell in from the oil fill tube, or off the bottomside of the valve covers or any sheetmetal that might have seen ambient air over the years. My thinking being, if the engine may have sat for years (and years) without running, perhaps any spot exposed to air may have rusted and eventually flaked off.

The motor was completely torn down and there was no signs of flaked off corrosion anywhere other than the cooling system.

 

[spasm3]

Perhaps it's casting flash that fell into the pan from vibration, higher rpm running. Maybe not from the cooling system at all.

 

[Donald]

And you have inspected the exhaust manifold and riser for water jacket damage.

FWC or RWC?