CORE AS-OIL COOLER 4W7188 - Caterpillar

Engine:Marine 3500 SeriesIntroduction
Do not perform any procedure in this Special Instruction until you read this information and you understand this information.The purpose of this Special Instruction is to raise dealer and customer awareness of proper installation and maintenance practices for copper nickel type sea water heat exchangers.Sea Water Strainers
Purpose
Strainers protect the sea water pump, the heat exchanger and other cooling system components from foreign material in the sea water. The foreign material can plug or coat heat transfer surfaces, causing overheating of the engine. Abrasive, foreign material will erode pump impellers and soft metal parts, reducing their effectiveness.Location
Install strainers below the boat's water line. Install the strainers as close to the sea water intake or to the sea chest as possible, (adjacent to the sea cock). The strainer must be installed so the strainer can be easily cleaned, even in the worst weather conditions.Type
While simple strainers, which require a shutoff of the sea water flow, are adequate to protect the engine, greater protection will result from using duplex strainers, which can be cleaned without interrupting sea water flow or engine power.Size
Properly sized strainers will impose no more than 9 kPa (36 inch of H2O) restriction to flow at conditions of full sea water flow. Suppliers can help in the proper selection of strainer size by providing the flow restriction of each size of strainer at varying conditions of water flow.Mesh Dimensions
The strainer screen should not pass solid objects that are larger than 1.600 mm (0.0625 inch) in diameter. Plate type heat exchangers require a mesh that is less than 3.000 mm (0.1181 inch). Tube type heat exchangers require a mesh that is less than 5.000 mm (0.1969 inch).Differential Pressure Switch for the Strainer
Schools of small fish, floating debris, or ice chips can plug a clean strainer in a few seconds. When the differential pressure across the connections of a strainer goes too high, the strainer needs to be cleaned. A differential pressure switch will provide early warning of the strainer being plugged, which could result in loss of cooling. The switch will also provide the precise location of the problem. A hightemperature of the fluid that is cooled by the sea water may indicate a loss of sea water flow.Marine Growth
Marine plants and animals will enter sea water piping and take up residence there. Many forms of sea life are very comfortable in the piping of an engine cooling system. The sea life can grow to a size that will threaten adequate flow. Darkness and the abundance of suspended food particles combine to create prime growth conditions for sponges, barnacles, and similar creatures. Strainers are no protection against creatures which are microscopic in size during their infant stages of life. Periodic operation of the vessel in fresh water will rid boats of salt water life infestation. In any case, it will be necessary to clean the corpses from the piping and from the passages of the heat exchanger.The use of high temperature alarms, pressure switches for the sea