1973 24' Searay Hard top w Chevy 350 overheating

[fdresser]

I have a 1973 OMC 225Hp outdrive on a Chevy 350 V8 with fresh water cooling ( San Juan Cooler). I had some stern drive work done and supposedly the water pump was changed, put a new 160 degree thermostat in. I had to replace the head gasket due to a blown one. The boat will run all day with out overheating if I keep the speed below 12mph but as soon as I power up beyond that it quickly overheats. Any suggestions? Could I have a blockage in the raw water system?

 

[Bondo]

Re: 1973 24' Searay Hard top w Chevy 350 overheating

I have a 1973 OMC 225Hp outdrive on a Chevy 350 V8 with fresh water cooling ( San Juan Cooler). I had some stern drive work done and supposedly the water pump was changed, put a new 160 degree thermostat in. I had to replace the head gasket due to a blown one. The boat will run all day with out overheating if I keep the speed below 12mph but as soon as I power up beyond that it quickly overheats. Any suggestions? Could I have a blockage in the raw water system?

Ayuh,.... Welcome Aboard,... Anything is Possible,....
Pull some lines, 'n Look at the flow in various places,...

How long ago was the impeller supposedly replaced,..??

 

[southkogs]

Re: 1973 24' Searay Hard top w Chevy 350 overheating

Had that exact thing going on with my Stringer last year. It was the stat. Make sure your new one is working properly.

Never hurts to change the impeller and see if that solves it. Kinda' cheap and easy on that drive.

 

[Walt T]

Re: 1973 24' Searay Hard top w Chevy 350 overheating

Its restricted somewhere. This is usually a classic impeller symptom.