Closed water cooling 5.0L Mercruiser

[DMat]

Good day everyone, I have a 1982 Chaparral and now after the restoration, I find Alpha One out-drive impellers do not supply enough raw water to the heat exchanger to run closed system cooling.
Basically I have 2 choices and wanted someone who knows of this issue to weigh in please:
Option 1: Keep the closed cooling system and run a 12v water pump in the raw water cooling intake hose to help boost water flow.
Option 2: Go back to standard raw water cooling and ditch the heat exchanger unit altogether. That said, I do need a photo or P/N of what the original 80's thermostat housing assembly looks like, so I can order one and re-route hoses.

Any input would be most welcome on these options.
Best
Dave

 

[Bt Doctur]

add a crank mounted pump or a belt driven Bravo pump

 

[alldodge]

^^^Agree and add thru hull water pickup

 

[Scott06]

Add crank driven or belt driven raw water pump with thru hull pick up as mentioned above.

Also need to leave the impeller in the drive and cut the hose between bellhousing and gimbal housing so water still flows through drive for cooling...

 

[kenny nunez]

Mercruiser recommends when a belt driven pump is used with fresh water cooling to connect the incoming water from the drive to the raw water through hull intake in a “Y” connection. This way the engine can be ran with the ear muff on the drive. I did the exact same thing on the Donzi I had.

 

[alldodge]

Mercruiser recommends when a belt driven pump is used with fresh water cooling to connect the incoming water from the drive to the raw water through hull intake in a “Y” connection. This way the engine can be ran with the ear muff on the drive. I did the exact same thing on the Donzi I had.

Agree

 

[Scott Danforth]

Just run a half system