STATOR AS 6T1389 - Caterpillar

A coolant flow warning system is now used on many Caterpillar products. The system uses a flow switch to measure the rate of coolant flow near the water pump outlet. This permits the earliest possible warning to the operator any time the rate of coolant flow becomes too low for safe operation.
The primary purpose of the system is to give a warning of rapid coolant loss soon enough to permit the operator to stop the engine before it is damaged. Tests show that loss of coolant when a lower hose breaks at the water pump inlet will activate the new system approximately 30 to 45 seconds before the heat causes cracks in the cylinder head. The system gives similar protection when a slow leak causes pump cavitation (air mixed with the coolant), or when the coolant level becomes too low for any reason.
For most warning system installations, the flow switch is connected to a warning horn, with a solid state relay switch in the circuit. A warning light can also be used, if desired. The solid state switch operates as a relay, and controls the circuit to prevent constant operation of the horn during the procedure to start or stop the engine.
Each time the engine is started or stopped, the warning system is activated for a short period of time as a test for correct operation of the system. On models that use the solid state switch in the system, the test time is limited to one or two seconds by the switch. On models that do not use the solid state switch, other methods are used to control the circuit.
A coolant flow warning system can be installed on most Caterpillar products. The necessary parts are available as a group for some machine models, and the separate parts can be ordered for engines and other machines. A system can be installed on any engine or machine that has a new water line part ("bonnet", "elbow", "pipe" or "adapter" for different models) with a boss for installation of the flow switch. Since each of the new parts (with a cover, gasket and necessary hardware) is a direct replacement for the canceled former part, the new part number can be found in Column 3 of the NPR (Numerical Parts Record) opposite the former part number. This makes possible the identification of parts which are adaptable to earlier models by a check of the part number for the existing part on the engine or machine. A list of the new water lines part for many models is shown in the parts chart.
The parts chart also shows the flow switch used on different models. Because of the differences in coolant flow characteristics between different engine models, the correct flow switch must be used for the specific engine. Other components of the warning system are basically the same, and those shown in the typical wiring diagram can be used.
During installation of a warning system, use 16 Gauge wire for all connections, and be