370ss500efi

my port header on the port engine has diminished water flow and is hot to the touch. there is noticable difference of water exiting muffler compared to the other 3. the sea strainer also shows less water than starboard engine. the boat runs fine at cruise, 3200 rpm. if i run faster the motor will start getting hot and eventually alarm will sound.
my sea strainers are clean, new impeller and housing, new thermostat. what could be causing the diminished flow on the one header and causing engine to overheat??
engines have 500 hours of saltwater use, flushed every weekend after use, never rebuilt or opened up. headers been replaced 3 seasons ago

32hustlin

Pieces of your last impeller. Sounds like you need to start cleaning out water lines

Jupiter Sunsation

Or you have hoses collapsing under pressure

370ss500efi

last impeller was fine not in pieces, plus sea strainer is plumbed after sea pump so no pieces should go past. i do not think it is a hose collapsing under pressure since at idle at dock port muffler has diminished flow

Griff

Inlet water neck from the Bravo drive is most likely full of corrosion.

370ss500efi

how do you recommend cleaning the water neck from the bravo drive? It is a bravo 3 BTW. Do the drives have to come off?