Mercruiser Impeller Debris

I have a Maxum 2100SD with a Mercruiser 5.0 MPI Alpha engine, with a closed cooling system. The impeller on the engine mounted sea pump failed. I removed the pieces of the fins from the hose up to the power steering cooler, but am not sure if there is more further down the line. The next stop along the path is the check valve, which is located on the bottom, port side of the engine, near the transom, and is relatively inaccessible. The check valve prevents me from back flushing the line from the heat exchanger.

How can I be sure all the bits and pieces of the impeller have been removed? Where is the likely spot for the debris to end up? How can I remove it?

Thanks for any suggestions.

Port side is the cool fuel unit but know if no check valve on mercruisers

According to my parts diagram, the fuel cooler is near the port riser, and the check valve is between the fuel cooler and the power steering cooler. I didn't look for the fuel cooler, but will verify this in a few hours.

got an engine serial number, the check valve may be associated with the pressurized draining system

I think the number is 1A056489. I am using a mirror to read the number near the flywheel cover.

[url]https://www.mercurymarine.com/en/us/parts-and-accessories/parts-catalog#epc::my_equipment

plug you serial number in here
Personally I would not trust that type of drain system No real way to test if the block and manifold drains drained completely. I see no benefit to a check valve in the water intake hoses. I would remove it and put a section of copper tubing in there
[/URL]

I verified the existence of a check valve and the serial number, 1A056489. The hose between the accumulator and the heat exchanger remains full of water, so the check valve is holding.