What Fresh Water Cooling is ------
“Fresh Water” cooling (also known as “Closed Cooling”) is the marine
version of the cooling system that you have in your car. Most marine
engines started out as a non-marine engine and were then designed to
have a clean non-corrosive antifreeze coolant circulating between the
engine and a "radiator". Normally air passes through the radiator and
cools the engine coolant but in the marine version of this cooling
system (fresh water cooling), the radiator is replaced with a "liquid to
liquid" heat exchanger. Instead of air, sea water passes through one
side of the heat exchanger and absorbs the heat from the engine coolant
and is expelled out of the boat through the exhaust. On the other side
of the heat exchanger the engine coolant is then circulated back into
the engine. Many marine engines use the initially less expensive,
“Raw Water” cooling system rather than “Fresh Water” Cooling. In this
case, polluted corrosive seawater is pumped directly into the engine.
The “Raw Water” eats away at the very base metal of a marine engine
causing permanent damage.
The difference between a full and half system kit ------
With a HALF System (Block Only), the treated fresh water is
circulated through the engine block, thermostat, expansion tank, heat
exchanger and circulation pump. It is not routed through the exhaust
manifolds. “Raw Water” which has removed heat from the engine through
the heat exchanger is then injected into the exhaust manifold, from
which it flows to the exhaust elbow to cool and exit through the
exhaust. The half system does not provide the same degree of protection
for your engine as a FULL (Block and Exhaust Manifold) closed cooling
system, but is generally easier to install, less expensive, and may be
the only option available if your engine's pump capacity, electronic
control system, or other factors prevent a FULL system from being safely
installed on a particular engine or boat.
In a FULL System (Block and Exhaust Manifolds), all parts of the
engine are cooled with circulated antifreeze. “Raw Water” which has
removed heat from the engine through the heat exchanger is then injected
into the exhaust elbow and exits through the engine exhaust. The full
system provides the maximum protection to your engine from the ill
effects of direct “Raw Water” cooling.
The difference between premium kits and standard kits ------
One difference is
that the premium kits are powder coated and the standard kits are
painted in primer only. Standard kits use standard factory fittings
and standard end covers. The premium kits use heavy duty cast end covers
and in full systems will replace the 1” hose to 3/4” NPT fittings in
the bottom of the exhaust manifolds with hi-flow fittings to achieve
higher flow rates. Another difference between premium kits and
standard kits is where the thermostat is located. On a standard kit
the thermostat is in the standard location and has a fixed or (static)
by-pass and on the premium kits have a built in high flow controlled
by-pass thermostat that insures proper flow of water through the heat
exchanger and the engine at all times, with water by-passing the heat
exchanger at start-up, when the thermostat is closed, to get the engine
up to operating temperature quicker and closing off the by-pass once
operating temperature is reached and thermostat opens. This guarantees
full flow through all temperature ranges. This is called a
thermostat-controlled by-pass.
