Closed Cooling, No Reservoir

[Lawren5]

I just purchased a 2001 Maxum 1900SC with a closed cooling system. The system has a heat exchanger in front of the engine made by Orca Marine Systems. It has a cap on top and when I took it off, I could see no coolant. The manual says to add a 50/50 mix of ethylene glycol and water to the overflow reservoir. The problem is that there is no reservoir. There is an overflow hose from the heat exchanger cap which would normally go to an overflow reservoir but in this case, the hose just empties into the hull.

Is this setup normal or did someone remove the reservoir?

[shrew]

Welcome aboard. I have a resevior.

[Lawren5]

Thanks, Shrew.
I've since discovered that there are aftermarket overflow tanks to prevent coolant from dumping into the bilge (http://www.marinediscounters.com/ser...pansion/Detail). Makes me think that not all boats with a closed system had overflow tanks installed.

[Frenchie]

Years ago cars didn't have an overflow either, the first time they got hot they discharged excess coolant and from then on they had an air space in the top of the cooling system. The expansion/overflow bottle is so fast to check (versus taking the cap off) and if you are going through coolant it will be easier to see that occurring. Sounds like a good add on.

[Lawren5]

Adding an overflow tank sounds like a good idea. I just need to find some space inside the engine compartment to mount it.

[mmwjr]

You'll need to mount the overflow tank high enough that when the engine cools it can draw coolant from the tank back into the heat exchanger. See the attached picture on where I mounted it on my previos boat. I made a custom bracket that attached to the heat exchanger mount.

[Lawren5]

Nice setup. It looks like you have two tubes going into the tank. One looks like the overflow from the heat exchanger but I can't make out how the other one is connected. Could you provide further details on how it's hooked up?

[mmwjr]

you are correct one goes to he nipple on the heat exchanger the second is an overflow for the tank to goes to the bilge. If you look closely you can see it just to the left of the crank pulley

[pascavone]

I've only seen a one way over flow tube, since the newer ones suck overfloat water back into the engine like your car dose since the 1980's.

The overflow cap expanse and contracts with the heat of the water, so your sucking air back into the system.

Easy to hang a bottle off the front.

Your not allowed to dump antifreeze into the water.

[mmwjr]

you car's overflow tank also has an overflow that will dump fluid onto the street. it's built into the tank.

since the overflow tank will have fluid in it the closed system will suck that back but you need to replace the fluid with air otherwise the tank will pull a vacuum and collapse.

yep you don't want to dump antifreeze into the bilge where it can get pumped overboard. this will only happen if you overheat the engine and will happen even if the system is built the way you describe it as the radiator cap's pressure spring will allow it to blow off pressure spraying antifreeze everywhere if the overflow tank doesn't rupture first.