What's this, a water filter?

[a64pilot]

So far as using the engine as a bilge pump.
Now if I’m sinking I’ll try anything, I’m the guy who will try putting my finger in the end of the barrel of a gun if I’m fixing to be shot, what have I got to lose?

However the engine actually pumps very little water compared to a bilge pump and it’s not at all unlikely that it will suck up some trash and overheat your engine, and now your without an engine.

Much better to install a secondary/ back up bilge pump. Perhaps higher up and have an alarm on it that sounds when it operates, that will alert you to your problem.

[Cheechako]

Originally Posted by danfarrell

Ive not been able to find another like it, but it looks like the Perko filters, but without the wing nuts . It has a 4" perko branded acrylic cylinder and cleaned up okay once I got it open. Maybe a Taiwanese part that only approximates the perko version, idk. I wonder if it was leaking; it's awfully green on the bottom.

It's definitely the engine raw water strainer. The 3 way valve is to switch from through hull inlet to bilge inlet so it can function as an engine powered bilge pump. Since the engine is freshwater cooled, I'm not sure how useful that is- does the freshwater pump function all the time? I'm not sure.

It looks exactly like the one that was on my Taiwanese boat in my Avatar. Most of that Chinese bronze is good stuff. Often they are just made locally and not necessarily a "brand name". You might say the 70's were the Chinese "Bronze Age"!

[danfarrell]

My confusion was pretty stupid I guess - the engine has a wet exhaust so, obviously, it must pump fresh water through the heat exchanger all the time. Both freshwater and saltwater pumps on my freshwater cooled Yanmar 3GMF are connected to the crankshaft via belt, so clearly neither one can turn on and off. But I understand my engine also has a thermostat. If it doesn't disable the flow of water, which assumedly would burn out an impeller, it must disable the circulation of freshwater through the heat exchanger, right?

However the engine actually pumps very little water compared to a bilge pump and it’s not at all unlikely that it will suck up some trash and overheat your engine, and now your without an engine.

That's a valid point and a good thing to keep in mind. Guess I probably can't count on the engine fresh water pump to pump out the bilge, but I suppose in an emergency it might make the difference. Here's hoping I never need to stick that finger in the barrel of a gun so to speak.

[MV Wanderlust]

Originally Posted by danfarrell

My confusion was pretty stupid I guess - the engine has a wet exhaust so, obviously, it must pump fresh water through the heat exchanger all the time. Both freshwater and saltwater pumps on my freshwater cooled Yanmar 3GMF are connected to the crankshaft via belt, so clearly neither one can turn on and off. But I understand my engine also has a thermostat. If it doesn't disable the flow of water, which assumedly would burn out an impeller, it must disable the circulation of freshwater through the heat exchanger, right?

The freshwater side of your engine has a thermostat, similar to your car. The thermostat is closed when the engine is cool and prevents the circulation of coolant (not just water but coolant like the antifreeze in your car) on the freshwater side. As the engine warms up, the thermostat opens and begins to allow coolant to circulate through the heat exchanger. The heat exchanger has two layers, if you will. One layer is tubing connected to the freshwater side of your engine and circulates coolant. The other layer circulates raw water from outside the vessel across the freshwater tubing. The ambient temperature raw water cools the coolant much like a radiator in your car. If everything is working correctly, the two layers of the cooling system never actually mix together. (That would be bad, m'kay)

[HopCar]

On the subject of using your engine cooling pump as an emergency bilge pump, a 3/4” pump will move between 500 and 700 gallons per hour. That’s about what a very small electric bilge pump will move. I don’t see much danger in using it as a bilge pump because you’re not going to leave plastic bags floating in your bilge. The strainer should catch any small bits that could cause a problem. You also would only use it if the boat was in danger of sinking. Since the option is already there, I wouldn’t remove it.