Question about water circulation in closed system

[stormyj]

Ok, so what Ive done so far.Mercruiser 350 mag mpi horizon, closed cooling system. This system uses the blue pump to open up drains. Of course, that didn't work at all. So, in case that doesn't work, your supposed to remove 5 blue drain plugs. 2 on the sea water pump, 1 fuel filter, 1 water distribution housing and 1 on heat exchanger. done. Bought the flush plugs for sea strainers and connected to bucket, closed sea cocks. filled, and antifreeze came out of the out-drive instead of flushing though the engine raw water side. I was going to fill the bucket and run engine, flushing seawater system with the antifreeze. So, I pulled seawater hoses off of risers and dumped antifreeze in until came out out-drives or out the heat exchanger. Anything else I should look for? The out-drives are down, so those should drain anything in them anyways correct? Of course the water distribution housings are cracked, someone didn't drain them the right way so will be taking them off and not sure what to do. I thought of just using some jb-weld and just draining with the blue plugs and filling with antifreeze. Any input would be appreciated.

 

[Bondo]

Ok, so what Ive done so far.Mercruiser 350 mag mpi horizon, closed cooling system. This system uses the blue pump to open up drains. Of course, that didn't work at all. So, in case that doesn't work, your supposed to remove 5 blue drain plugs. 2 on the sea water pump, 1 fuel filter, 1 water distribution housing and 1 on heat exchanger. done. Bought the flush plugs for sea strainers and connected to bucket, closed sea cocks. filled, and antifreeze came out of the out-drive instead of flushing though the engine raw water side. I was going to fill the bucket and run engine, flushing seawater system with the antifreeze. So, I pulled seawater hoses off of risers and dumped antifreeze in until came out out-drives or out the heat exchanger. Anything else I should look for? The out-drives are down, so those should drain anything in them anyways correct? Of course the water distribution housings are cracked, someone didn't drain them the right way so will be taking them off and not sure what to do. I thought of just using some jb-weld and just draining with the blue plugs and filling with antifreeze. Any input would be appreciated.

Ayuh,..... Welcome Aboard,..... Take all that crap off, 'n deep 6 it,.....

Especially on a freshwater cooled motor,......

You only have to winterize the raw water side, the motor side should already be antifreeze,.....

 

[stormyj]

Ayuh,..... Welcome Aboard,..... Take all that crap off, 'n deep 6 it,.....

Especially on a freshwater cooled motor,......

You only have to winterize the raw water side, the motor side should already be antifreeze,.....

Not sure what you mean by taking it off. I take it your talking about the water distribution housing. And yes, it is a piece of crap. Why make anything out of plastic. I just dont know. Anyway, like i said, i will be just using the blue drain plugs and fill with antifreeze in winter. I take it, that the exhaust and raw water drain is through the bravo 3 drives

 

[Scott06]

Not sure what you mean by taking it off. I take it your talking about the water distribution housing. And yes, it is a piece of crap. Why make anything out of plastic. I just dont know. Anyway, like i said, i will be just using the blue drain plugs and fill with antifreeze in winter. I take it, that the exhaust and raw water drain is through the bravo 3 drives

@Bt Doctur has shown versions of the distribution housing he sweated out of copper plumbing fittings

 

[Lou C]

For your closed cooling system you need to make sure the raw water side of the heat exchanger is drained, as well as the raw water hoses feeding it, the impeller, and exhaust elbows (if you have a full system the manifolds are on the closed side but the exhaust elbows are on the raw water side and must be drained. If you have a half system (manifolds on raw water side) those must be drained as well. In addition to that, any fuel coolers/oil coolers will need to be drained since they are on the raw water side.
If you have closed cooling, instead of this plastic junk from Mercruiser, you should simply use a winterizing tank with a livewell pump to pressurize the antifreeze flow into the outdrive water intakes. Simple, fast and fool proof. Fill it with 5 gallons of good marine antifreeze and hook up the pump to one of your batteries.
When I repower my boat it will have a half closed system and that's what I am going to do. If I had one of those drain systems (which work OK when the boat is new but they are prone to clogging) I would seriously consider removing all of it to avoid problems with the plastic parts.
I winterized my brother's 2020 Merc 4.5 V6 equipped boat with the plastic drain system. It looks like they made the fittings and hoses connected to the block bigger to avoid clogging and it worked as advertised, but we also filled it with AF to cut down on internal corrosion which is what makes these systems risky over time...we're in salt water...