Noah sez:
"then the muff's won't flush
the fresh water side. You may basically have a "heat exchanger",
where engine heat is transfered to a fresh water system, through the
exchanger, and then to salt water from the lower unit pump.

Does your manual describe this?
Do you have a heat exchanger on the engine?
If so, you will need to flush the fresh water side seperately...."


Yo Fellas! If your engine is FWC (fresh water cooled) then that means the
engine is being cooled by a mixture of fresh water and anti-freeze. Just like
in your car/truck. Instead of a radiator, like in your truck, you have a heat
exchanger (which is all a radiator is-only it transfers heat to the air) that
transfers heat to the water you are floating in as it is pumped through the
exchanger by your raw water pump.
You can use earmuffs etc to flush the raw water side of the system (water pump,
heat exchanger, exhaust system parts) which is a good idea.
Tell me why you think you need to "flush the fresh water side seperately".
Or at all.
Think!
There is not now nor has than ever been salt water in the "fresh water side"
that needs to be flushed..
Best wishes
Mike