1979 Searay

[wilbertfilcek]

I have a 1979 Searay and it overheats after I run it for about 10 minutes (not in idle). It's a Mercuiser, inboard/ outboard and it is open system. Do I NEED a thermometer in it? I ran it with one in it the first time and it overheated melting all my hoses. I found out it overheated the first time because I needed a new water pump. I bought a new water pump and hoses. I took it out to the lake without the thermometer and it over heated again after 10 minutes. Seeing I have an open system do I need a thermometer? If so, is there any other solutions why my boat is overheating. I read the other postings and I have already checked everything.

Thanks

[scotte]

When you checked everything did you check the impeller?

[Inthewind]

Sounds like your exhaust risers may be rusted up causing clogging and may need replacing, they only last about three years especially if the boat has been run in saltwater. If the vessel has only been run in fresh water only, than I doubt if the exhaust risers are your problem. Could be your thermostat is not opening up when it gets up to temperature. Good Luck.

[Steve Rust]

When you say open system do you mean raw water cooled? I would say yes you do need a thermostat. Running without one the engine will tend to run cooler that it should. You can test the thermostat by putting it in a pot of water on the stove and using a thermometer check that it is opening at or near the rated temperature.

[wilbertfilcek]

Figured it out! I put in the thermometer and I bad to clean out the new water pump. When I replaced it, I didn't clean the filter that sucks the water in and all the dirt and stuff went back into it. I cleaned it out and it works fine. Thanks for the suggestions!!