Do you have fresh water cooling (with heat exchanger) ?
I do on my Mercruiser 260 5.7. During clean water flush, a
hose must be connected to BOTH the muffs and to the engine's
cooling water intake circuit. On mine, a garden hose connection
was added to the engine cooling water intake to make it
convenient to connect clean water to the engine intake during
flush. I have to close the thru-hull cut off valve during
flush, and ALWAYS open that valve as soon as flush is done.

IF you have raw water cooling (without the heat exchanger), then
you only need clean water to the muffs to flush, bcz the engine
cooling water, in that case, comes from the outdrive.

J K


Hello,

Just reading the manual on my 2001 Mercruiser 3.0 and its
sorta confusing when it comes to flushing the engine. Has some
"salt water" connectors, blue hoses, etc. Can I just simply
flush with the muffs on for like 5-10 minutes with the engine
running?\

TIA!