Systems Operation 3408E and 3412E Engines for Caterpillar Built Machines

Cooling System SMCS - 1350

This engine has a pressure type cooling system. A pressure type cooling system gives two advantages. First, the cooling system can be operated safely at a temperature that is higher than the boiling point of water. Also, cavitation in the water pump is prevented. It is more difficult for air or steam pockets to be made in the cooling system.

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Product: MOTOR GRADER Model: 24H MOTOR GRADER 7KK Configuration: 24H Motor Grader 7KK00001-UP (MACHINE) POWERED BY 3412E Engine

Media Number -SENR1018-03 Publication Date -01/09/2004 Date Updated -10/09/2004

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Illustration 1 g00678773

Cooling system schematic

(1) Shunt tank

(2) Radiator

(3) Jacket water pump

(4) Engine oil cooler

(5) Aftercooler

(6) Separate circuit aftercooler pump

The cooling circuit consists of two water pumps. The jacket water pump (3) provides water to the engine oil cooler (4) and the power train oil cooler (9). The jacket water pump also carries heat away from the engine (8) to the radiator (2). The water from the jacket water pump is broken into two circuits in the engine head. The two circuits carry heat from both rows of cylinders. The water is then passed through a thermostat. There is one thermostat on each side of the engine. The thermostat then directs the water to either the radiator for cooling or to the pump for recirculation if the water is cool.

The separate circuit aftercooler pump (6) provides water to the aftercooler (5). This water reduces the inlet manifold temperature. All water flow in this circuit goes directly to the radiator (2). This water does not pass through a thermostat. There are two radiator cores. Water enters the radiator from both circuits. The water is divided between the radiator cores. The amount of water that goes to each radiator core depends on the amount of water that is directed to the radiator from the thermostats.

Coolant Conditioner Note: Coolant conditioner is not required if the cooling system is using Caterpiller Extended Life Coolant.

Some conditions of operation can cause pitting on the outer surface of the cylinder liners and on the cylinder block surface next to the cylinder liners. This pitting is caused by corrosion or by cavitation erosion. A corrosion inhibitor is a chemical that provides a reduction in pitting. The addition of a corrosion inhibitor can keep this type of damage to a minimum.

The coolant conditioner element is a spin-on element that is similar to a fuel filter and to oil filter elements. The coolant conditioner element attaches to coolant conditioner base that is mounted on the engine or mounted on a remote location. Coolant flows through lines from the water pump to the base and back to water pump. Coolant constantly flows through the coolant conditioner element.

The element has a specific amount of inhibitor for acceptable cooling system protection. As the coolant flows through the element, the corrosion inhibitor goes into the solution. Two basic types of elements are used for the cooling system: the precharge element and the maintenance element. Each type of element has a specific use. The elements must be used correctly in order to get the necessary concentration for cooling system protection. The elements also contain a filter. The elements should remain in the system after the conditioner has dissolved. This will allow proper flow of the coolant through the engine. Refer to Operation and Maintenance Manual, "Supplemental Coolant Additive (SCA)" for more information.

The precharge element contains more than the normal amount of the inhibitor. The precharge element is used with new coolant after a complete change of the coolant. This element must add enough inhibitor in order to bring the complete cooling system up to the correct concentration.

(7) Turbocharger

(8) Engine

(9) Power train oil cooler

The maintenance elements have a normal amount of inhibitor. The maintenance elements are installed at the first change interval. A sufficient amount of inhibitor is provided by the maintenance elements in order to maintain the corrosion protection at an acceptable level. After the first change interval, only maintenance elements are installed. In order to provide the cooling system with protection, maintenance elements are installed at specific intervals. Refer to Operation and Maintenance Manual, "Maintenance Interval Schedule" for the correct maintenance of the cooling system.

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Sun Jan 28 09:40:02 EST 2007