Here's the lazy man's "Well, it's better than nothing" method of "flushing"
the cooling system.

Every time  I open the engine cover for any reason, I siphon the coolant
expansion tank empty and refill with 50/50 mix of distilled water and
whatever antifreeze they are selling at Costco.  I've done it about 10 times
and the coolant now looks remarkably clean.

-bret

1982 Diesel Westfalia
Saint George, Utah

BONUS "TIP" - For a hillbilly brake system flush, liberate the turkey baster
from the kitchen drawer and suck the brake fluid reservoir empty.  Refill.
Warsh and return that turkey baster!