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ELECTRIC FW COOLING JUST GOT EVEN BETTER ... A NEW BRUSHLESS DC MOTOR DRIVEN PUMP IN ADDITION TO OUR ALREADY PROVEN JOHNSON PUMPS!

Diagram of Cooling System

{Electric Antifreeze Pump}

Bosch Pump

Any Freshwater Cooling System (actually antifreeze cooled) requires that there be two pumps in the system. One is the raw water pump and one is the antifreeze pump. The "normal" FWC System uses a mechanical pump for both applications. We now offer our tried and proven Johnson Electric pump(s) as well as a BRAND NEW BRUSHLESS DC electric pump for the antifreeze circuit. With this new type of electric motor in the pump there is no "failure" anxiety as the pump/motor is rated at more than 5000 hours .

The image to the right shows this new antifreeze pump utilized in the installation of the Indigo Electronics AT-4CE Fresh Water Cooling System on an Atomic 4. The most significant and unique aspect of this system is that this new heavy duty, seal-less, brushless antifreeze pump, manufactured by Bosch, can be mounted in-line in most any convenient location. This feature insures that this system can be installed on any vessel. Physically, the pump is about 3.25" in diameter and about 4.6" long including the suction hose connection.

The existing mechanical pump remains the raw water pump. However, the pump discharge is re-routed to provide cold raw water to the new Heat Exchanger instead of to the engine block. The new centrifugal antifreeze pump circulates antifreeze through the block, manifold and Heat Exchanger. Why an electric antifreeze pump? First and foremost, this pump can easily be mounted in any engine compartment. It mounts "in-line" and just needs to be below or inline with the Heat Exchanger outlet. Secondly, the electric pump consumes about 1/2 as much power as the mechanical pump. Per the manufacturer of the pump, estimated service life is over 5000 hours.

The single most important factor for long life of the typical pump motor is the voltage at which it operates. This is NOT the case with this Brushless DC pump. Utilizing PWM (Pulse Width Modulation) technology, the speed of the brushless motor remains constant with an input voltage ranging from 8 to 16VDC. For this reason there is no need to have a Ballast Resistor to manage the voltage level and no concern about overloading the motor with either too high or too low voltage.

This centrifugal pump is a higher pressure pump than most typical centrifugal pumps used in this application as can bee seen in the curves to the right. It will readily provide sufficient coolant flow to a "standard" Atomic 4 configuration. This is to say that the standard 1/2" hose barb inlet to the block, the 3/8" hole in the "diverter cap" within the block cavity and the standard 1/2" hose barb fittings on the head and manifold can remain in place for successful cooling operation. Having said that, one must still be aware that an engine that has been raw water cooled for many years may have significant blockages in cooling passages between the block and head and within the manifold itself. These can significantly reduce the coolant flow to the point that overheating occurs and will require corrective action to restore the flow. Of course, if you are in the process of overhauling your engine, it is still a good practice to increase the size of hose barb fitting to at least 5/8" and to enlarge the hole in the "diverter cap" to 1/2". A reducing hose barb fitting (3/4 x 1/2) is provided in the kit to transition between the existing 1/2" ID hose and the 3/4" discharge connection on the pump.


The kit comes complete with a special power connector for the Bosch pump, all hose fittings, clamps, hardware and mounting brackets. The only material not provided is 1/2, 5/8 and 3/4 inch heater hose for the connection of the various components as each installation is very much different with regard to the location of the heat exchanger.





Johnson Pump(s)


{Dual Electric Antifreeze Pumps in Series} {Single Electric Antifreeze Pump}

The images to the right show the Johnson pumps that we have offered for the past 6 years with the Indigo Electronics AT-4CE Fresh Water Cooling System on an Atomic 4. The most significant and unique aspect of this system is that this heavy duty, seal-less, magnetic driven antifreeze pump can be mounted in-line in most any convenient location. This feature insures that this system can be installed on any vessel.

Download Johnson Pump Manual

The existing mechanical pump remains the raw water pump. However, the pump discharge is re-routed to provide cold raw water to the new Heat Exchanger instead of to the engine block. The new centrifugal antifreeze pump circulates antifreeze through the block, manifold and Heat Exchanger. Why an electric antifreeze pump? First and foremost, this pump can easily be mounted in any engine compartment. It mounts "in-line" and just needs to be fairly low in the system like on the top of the transmission housing. Secondly, the electric pump consumes about 1/3 as much power as the mechanical pump. Per the manufacturer of the pump, estimated service life is 600 to 1000 hours.

The single most important factor for long life of a typical DC pump motor is the voltage at which it operates. Testing by the manufacture has demostrated that maximum life can be obtained by operating the pump in the 12.0 to 13.0 volt range. Typically, however, the voltage available at the "+" terminal of the ignition coil, the point at which it is recommended that the pump be wired, is between about 13.0 and 15.0 volts depending on how the alternator voltage regulator is set up. In order to get the voltage down to approximately the recommended level, a properly sized "ballast resistor" will be installed in the red wire of the pump motor adjacent to the fuse. Please give a call to allow us to precisely "tune" the motor voltage to your specific system. You will need to measure the operating voltage (engine running and alternator working) at the "+" terminal on the coil and the appropriate sized ballast resistor will be installed prior to shipment of the kit. If you are unable to obtain the operating voltage, a .5 Ohm ballast resistor will be installed as a default. The .5 Ohm resistor will properly cover voltages from 12.8 to 13.8 volts.

For absolute reliability, a second pump can be installed in series with the first pump as shown above. Only one pump at a time need be operated (no fuse in the second pump) and when the primary pump fails, a fuse is installed in the second pump and the system is restored to normal operation.

The centrifugal pump(s) used are low pressure pumps. For successful operation, two "piping" changes must be made. 1) The crossover hose between the thermostat housing and the manifold must be increased in size to 5/8" ID hose. Fittings are included in the kit for this change. 2) The discharge from the manifold to the Heat Exchanger must be at least 5/8" ID hose. The existing 1/2" ID hose inlet to the side plate on the block will remain 1/2" ID. A reducing hose barb fitting (3/4 x 1/2) is provided in the kit to transition between the existing 1/2" ID hose and the 3/4" discharge connection on the pump.









Heat Exchanger

{Heat Exchanger, Recovery Bottle, Mounting Bracket}

The Heat Exchanger is an all copper "shell and tube" design with 4 passes. Raw water circulates through the tubes and antifreeze circulates around the tubes. The Heat Exchanger is designed to operate totally full of antifreeze at a pressure of about 5 psi with an antifreeze recovery bottle provided to collect and return antifreeze to the system. A bracket is provided for mounting the Heat Exchanger to a convenient vertical surface but it can also be mounted at up to a 45 degree angle if space does not permit a vertical installation. The current thermostat configuration is still utilized which includes the bypass hose which runs from the side plate "T" connection to the thermostat outlet housing under which the thermostat is housed. As with Raw Water Cooling, it is critical that the internal bypass "boss" in the outlet housing be as designed and not wasted away after years of salt water attack. (it may be worth while to look at yours if you have not done so in a while. The "boss" control surface which the thermostat closes against should be flat with no craters in it and no more than 7/16" below the housing gasket surface). An improved Thermostat Kit, which eliminates the current thermostat and bypass hose, is offered as an option ($115 with purchase of FWC, $130 otherwise). An additional Product Improvement is the Belt Tension Device which makes adjusting the alternator belt tension a snap.




Start-Up Accessories


As a result of the lessons learned since introducing the Indigo Electronics AT-4CE kit, each kit will now be shipped with a Pump Pressure Gauge Assembly and a Coolant Filter Assembly. The gauge is to be installed between the pump discharge and the 1/2" hose going to the inlet to the block. Pressure readings obtained have been found to be an excellent means of evaluating the flow of coolant through the engine and allowing you to compare your readings to known systems. The Coolant Filter has always been a suggested complement to a new system but by having one provided, you can be assured of cleaning the debris out of your system with both filter media and a magnet and avoid frustrating overheating situations during initial operation. Below are images of the Pump Pressure Gauge Assembly and the Coolant Filter Assembly. A Core Charge of $25 and $15 respectively will be charged when the kit ships. Once your system is fully functional, you may elect to return one or both items for a full refund. If you decide to keep then, that is fine as well.





SMALL DIESEL APPLICATIONS: Most any of the small auxiliary diesel engines found in sailboats can utilize this System. The discussion above is worded around the Atomic 4 but is nonetheless applicable to small diesels. The existing raw water pump is similarly re-routed to supply raw water to the Heat Exchanger and the new electric pump is installed so as to circulate antifreeze through the block and manifold. Please call with any additional questions.

Thank you for your interest in the Indigo Electronics AT-4CE Cooling System. Fresh water cooling not only prevents deterioration of the block, head and manifold, but it allows the engine to run at higher temperatures (170-180 F) promoting improved combustion and performance.

Download Thermostat Installation Instructions

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Indigo Electronics, Inc.

105 Pipe Kiln Court
Williamsburg, VA 23185

Order Today. You never knew sailing could be so much fun!
1-800-428-8569 toll free
or 757-593-8569

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