Need Help With Freshwater Cooling.

[Homerr]

I used to install these things years ago, but getting old has seem to catch up with my memory!<br /><br />I have a Mercruiser with a 351 Windsor Ford engine. (Don't know the mercruiser identification, but I think its 5.8L ?)<br /><br />Anyhow, it has a heat exhacger mounted on the front of the engine. The exhaust manifolds say NICSON on them. They are THRU-HULL exhaust.<br /><br />How does this work? I can see that the large radiator hoses go from the exhcanger to the engine water pump and block. These hoses have antifreeze in them.<br /><br />There is one hose coming FROM the stern drive/gimball and connecting to one side of the heat exchanger. There are other hoses coming out of the exhaust manifols both front and back and eventually hook into the bottom of the heat exchanger, one on each side of it.<br /><br />Ok, now this is where I'm confused... <br />Obviously the exhaust needs cooled since there are hoses coming out of them, but how does water get into them? I don't see any pumps other than the water pump mounted on the engine (like a car pump)Ther is no sea-water pump.<br /><br />Hooking a hose to the stern drive doesn't seem to work. Could it be clogged somewhere? Even so, with nothing to 'pump' it in, how do I get water?<br /><br />And how would a person be able to run this engine out of the water like you would if it was a normal stern drive intake?<br /><br />This engine has some plastic garden hose connections inline on the hoses that go to the exhaust (2 on each side). I'm assuming this is where a person can hook a garden hose to when running the engine out of the water, but I have no idea if this will work, or pump water into my engine!<br /><br />Any web sites or information on howq this thing works and/or looks like inside would be GREATLY appreciated!!<br /><br />Thanks,<br /><br />H.

 

[Boatist]

Re: Need Help With Freshwater Cooling.

I am no expert but the engine is filled with antifrezz and water is circulated by the water pump on the Engine. Engine should have a thermostat to regulate temp. Water pump also moves water thru heat exchanger when thermostat is open. Hose coming from outdrive is sea water pumped by water pump in outdrive and it runs thru pipes in heat exchanger to cool engine after that it comes out of heat exchanger and goes into each exhaust manifold to cool manifold, again this water is sea water. The water exits the manifold to a riser at the top rear of each manifold and then down and out thru prop. Since the manifolds have sea water in them if you run in salt water they will go bad every 4 to 6 years if you flush them, sooner if you do not. When they start to go bad not uncommon to have rust and scale pulg the holes where water exits the manifold into the riser. To run it out of water you need ear muff or some type hose connection to outdrive water pump or you will burn up outdrive water pump in a few minutes. Good Luck

 

[oldboat1]

Re: Need Help With Freshwater Cooling.

not sure what you mean by saying the hookup to the intake on the outdrive doesn't seem to work. That should produce input and output just like an outboard -- unless, like an outboard, the impeller is shot or there is an obstruction somewhere.<br /><br />My point of reference is a '77 Chris Craft inboard with fresh water cooling. The pump on the front of the engine draws in seawater to cool the exhaust manifolds and the antifreeze mix in the heat exchanger tank. I think it also runs through the transmission oil cooler, but would have to check on that. The water pump on the engine also circulates the antifreeze mix through the block. Sea water is discharged out the exhaust outlets on the transom after being circulated. I presume the raw water exhaust on a sterndrive would be out of the through-hub exhaust or out of an opening just below the ventilation plate on the lower unit.<br /><br />It sounds a little unique to have connectors for flushing in addition to the normal flushing available by using muffs. Maybe the connectors are in the freshwater cooling line(s) and would permit backflushing of that system. If the connectors are indeed in the raw water lines, I'm sure you would still need muffs on the lower unit intake or the impeller will be ruined.

 

[clanton]

Re: Need Help With Freshwater Cooling.

If there is no raw water pump on the engine, its on top of the lower gearcase. The heat exchanger has to have raw water, or a big cooling fan. You should be able to turn streering wheel hard lock to the right and see the hose from gearcsae to transom bracket, then locate hose inside boat, disconnect hose, install flush muffs, start engine, you should have lots of water.

 

[Homerr]

Re: Need Help With Freshwater Cooling.

Thanks for the reply guys...<br /><br />After some research, I found that the drive has a pump in it... Call me an idiot, but I didn't know one was there!<br /><br />Why I can't get any water through it is another story. Does the drive have to be engaged to pump water?<br /><br />I'm pulling the drive anyways and have the pro's go through it. It's been sitting way too long for me to just toss it back in the water and hope it holds up.<br /><br />H.

 

[Boatist]

Re: Need Help With Freshwater Cooling.

The inpeller in the outdrive if it is good will pump water anytime the engine is running. It does not need to be in gear. With ear muff on lower unit water intake and water turned on take the hose off that comes from the outdrive where it hooks to the heat exchanger. Start engine and you should get lots of water. If you do not either outdrive water pump is bad or a plugged screen. If you do have water out that hose, stop engine and put hose back on. Again start engine and look for water coming out center of prop. If you have water all is ok. If no water I would bet on blockage between the exhaust manifold and the Riser. Good luck