Sand/dirt when drained manifold for thermostat replacement

[Kubaat3lover]

Hello folks, Mercruiser 4.3 05’ and alpha gen2.

my thermostat stuck opened so i went ahead and replaced it,
drained block and manifold and I have found dirt and sand (?) in the manifold while draining, the drain from block was clear and fine .
Any ideas why I have sand ? Engine was at the normal temperature
i don’t boat in the shallow water, usually approx 40-50ft minimum, I drain engine every year during winterization and never had this crap Before I think.
Last year I’ve replaced impeller So it’s new. Also because of that sand I would like to check the impeller this winter because of this sand, do I need to replace the gaskets in the housing impeller after inspecting?

And this is my thermostat housing, I want to clean it but I have also this “balls”, do they need to be replaced or adjusted??
take care

 

[Kubaat3lover]

Sorry I’m posting from my iPhone and pic uploading doesn’t work fine

 

[Scott Danforth]

very common for sand, dirt, shells, parts of fish and anything else in the muck when you run aground or floating in the water to make it into the water jacket and manifolds.

every boat I ever owned will suck debris up with the impeller and push it into the block, heads and manifolds if the engine is raw water cooled.

if your heat exchanged cooled, it normally plugs the heat exchanger

the larger chunks normally get stuck in your power steering cooler as that will be the first "strainer" in your system

 

[Kubaat3lover]

Thanks how to clean it or flush??

 

[Bondo]

Thanks how to clean it or flush??

Ayuh,..... Just run it,...... It'll flush itself out, 'n probably gather more crap again, 'n flush itself out again, over, 'n over,.....

That's why it's so important to poke, 'n prod the drain holes when drainin' for winter,......

 

[Kubaat3lover]

Yes I always do that, by the way. When inspecing impeller and opening the housing, can I reuse the gasket or its only 1 time use? Ive replaced whole kit last winter

Thanks

 

[Scott Danforth]

one-time use