COOLING SYSTEMTwo types of cooling systems are employed on Perkins marine engines, i.e., indirect and keel cooling.Indirect Cooling: This system incorporates a heat exchanger, coolant in a closed circuit and raw (sea) water used as thecooling medium. The raw water discharge can be routed into the exhaust silencing system. A thermostat in the closedcircuit system keeps the engine at an operating temperature of 150 - 200°F (65 - 93ºC) for 4.108 engines and 168 - 197°F(75 -91 °C) for the remainder of the marine engine range. Two water pumps are used.Keel Cooling: This is the same system as above except the dissipation of heat is accomplished by pipes located outsidethe hull, usually at an angle between the keel and the garboard strake. The length and diameter will be determined by theengine requirements.Coolant Capacities: HeatExchangerSystem4.108(M)4.154(M)2 U.S. Gallons (7.57 Litres)3 U.S. Gallons (11.36 Litres)6.354(M)AllV8.510(M),TV8.510(M)5.4 U.S. Gallons (20.44 Litres)9.3 U.S. Gallons (35.2 Litres)4.2363.5 U.S. Gallons (13.25 Litres)COOLING SYSTEM MAINTENANCERubberImpellerTypeWaterPumpThis type of pump is used for raw water circulation.The pump should never be run in a dry condition (impeller blades will tear) and, if the engine is not to be operated for anylength of time, it will be necessary to pack the water pump with MARFAK 2HD grease. (If this is not available, glycerinemay be used). This is effected by removing the pump end plate' to give access to the interior of the pump. Insert thegrease, or glycerine, through the top-most pipe connection (after removing the rubber hose). Turn the engine over tospread the lubricant. This treatment is usually effective for about three months and should be repeated if stored for alonger period of time.'Refer to Page 43.With 4.154 marine engines, the raw water pump will have to be removed from the engine to gain access to the end plate.NOTE: ALWAYS KEEPA SPARE IMPELLERON BOARDFig. 12, Typical HeatExchanger CoolingSystem UsingSeparate HeatExchanger and EngineOil Cooler.-54-
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