Cooling system

[kwoolard]

Hi all,<br /> <br />Can anyone explain the cooling system on an inboard? I have done some research and realized there are two ways of cooling-closed looped with a heat exchanger-or open looped with raw sea water. I have recently taken my father in laws' boat out of storage to get running and set it up for the winter. However, I noticed that alot of the water lines were disconnected where he had previously winterized it and I have somewhat of an idea where the lines go but want to be sure. I assume that the engine I have has an open loop cooling system since I cannot find a heat exchanger or a resorvoir for the antifreeze. Unfortunately, my father in law cannot be here to help me figure it out. <br /><br />Another question, I have know there is a water pump driven off of the crank and one on the lower unit of the stern drive, but I have noticed another pump driven off of the crank as well. Much smaller than the pump with lines running out to the risers. Are there three water pumps an inboard?

 

[snapperbait]

Re: Cooling system

HI Kwoolard..<br /><br /> Many differences between manufacturers.... If you could give us the make (mercruiser, volvo, OMC, ect.?) and perhaps a model # or even a picture would help...<br /><br />have a look at this.. http://www.iboats.com/cgi-bin/ubb/ultimatebb.cgi?ubb=get_topic;f=24;t=001250

 

[crazy charlie]

Re: Cooling system

Kwoolard,it sounds like a mercruiser set up with a sea water pickup pump.Usually the pump in the outdrive is used for cooling.On some there is a seawater pump under the motor with strainers in them.This sounds like what you have.Charlie

 

[kwoolard]

Re: Cooling system

Thanks for all the help. The engine I have is a 302 Ford with a Mercruiser Outdrive. I think a 1973 model engine but not sure about the outdrive. From what I can tell, my engine has two water pick ups (one right beside the engine through the bottom of the boat hull and the other from the water pump impeller in the Outdrive.) As shown on the diagram from the link above both of these water pickups are pumped through what I am calling a "booster pump" up to the circulating pump. If I am wrong about this correct me. <br /><br />What is the reason for two water pickups(the hull and the outdrive)?????<br /><br />Are there any kits out there to convert to a closed loop cooling system??? <br /><br />What type of cleaning agent could I circulate through the cooling system to remove any deposits?????

 

[Trent]

Re: Cooling system

My bet is the waterpump in the outdrive has been removed. It is not needed when you have a "raw water pump". Did you look in the lower unit?? Yes you can buy a kit for closed cooling. If its a freshwater boat its really not needed.

 

[kwoolard]

Re: Cooling system

I will be using this boat mostly in fresh water and brackish water. I will hardly ever use it in pure saltwater. I haven't taken apart the lower unit but I do know there is a water pump in it. I hooked a seperate line up to the pick up from the lower unit and a seperate line to the raw water pump and the lower unit pumped water when I attached flush muffs to it. I assume that the pick up through the hull of the boat is for high speed since the water pump in the lower unit will not be able to pump enough water to cool the engine.<br /><br />Where is the thermostat on this engine if there is one?<br /><br />Another question that I have: I have narrowed down the engine model of my boat to three models via the mercruiser outdrive model number. It is a 401***x number, so I think I have either an 1973-1977 model 888, 225, or a 225s. Can anyone tell me the difference between the three and also tell me where I can find the engine model number to be sure?