496 Mercury Bravo 3 Over heating

[Desertson1410]

I have a 2004 Larson 270 with single 496 HO Bravo 3 and here is my issue can you please help so i can get back in the water...
1st time I put my boat in the water it over heated for the new season of 2020 around mid April. I figured it could be the impeller if not then the thermostat. I removed the water pump from the engine and removed the impeller. There were a few pieces that i found in the bilge and i picked out most of the pieces from the water pump housing. After the install we took it out and ran just fine took it out for about 1 hour of continuous running without it over heating... So I bring it home and connect the mickey mouse ears to run fresh water in it because we had taken it in salt water and after about 7 min of running it started to over heat again. sad face... I read some where that these boats need to be under water pressure and the over heating might go away again.I went ahead and took off the water lines up to the transmission cooler and the hose right after and did not find any pieces. I felt and squeezed all of the lines up to the thermostat housing.I have not changed the thermostat yet does any one have any suggestions on where to go from here or should i just put it back in the water and see if it over heats again. thank you in advance for taking the time to read my cry for help.

 

[Scott Danforth]

find the pieces of the impeller that are missing....... once you dig those out of the area that they are plugging,........ you should be good to go.

 

[alldodge]

The 496 is a closed cooled motor, it has a heat exchanger (HE). Remove the end caps on the HE and look at the tubes (no antifreeze will leak out). Remove hoses off power steering cooler and look through it

No need to remove the thermostat unless it it continues to overheat because its in antifreeze and not raw water

What does the inside of the pump housing look like?
Is there any scoring ?