BOLT 8T1489 - Caterpillar

3300, 3400, 3500 Families Of Marine, Industrial, and Generator Set EnginesReference: Service Magazine, December 16, 1985, Page 1, "Troubleshooting Of Jacket Water Heaters".Description of Change: New jacket water heaters on the above engines have several improvements: ...Heater thermostat life is much longer because the sensing bulb is now near the bottom of the heater. This location causes the thermostat to cycle at about 1/20 of the rate in the former heaters.
...A hose is used for thermal insulation.
...The insulation hose has an indented area for the mounting bracket, thus assuring that the new heaters are always installed in the vertical position.
Adaptable To: For the 3300 Family Of Engines, and for only the 3406 and 3408 Engines, a 7C1710 Heater (120/240 Volt, 3kW) replaces either the former 5N5739 Heater (120 Volt, 3kW) or the former 5N5740 Heater (240 Volt, 3 kW). For the 3412 Engine and the 3500 Family Of Engines, a single 7C1709 Heater (240/480 Volt, 6 kW) replaces either two former 5N5739 Heaters, or two former 5N5740 Heaters.
The new 7C1710 Heater can be used as a replacement for a single 5N5739 Heater, or for a single 5N5740 Heater in any application. Install and connect the heater so both hoses have an upward slope with no bends. See Reference Article. The 7C1710 Heater comes normally connected for 240 Volts. If it is to be connected to a 120 Volt circuit, reconnect the two elements in parallel. See Illustration 1.
Illustration 1. Series and parallel connections for the two heating elements in each 7C1710 Heater.Two 3B6491 Couplings are needed to connect the 1-11 1/2 male pipe threads on the new heater. The former heaters have female threads.
Although a single 7C1709 Heater (240/480 Volt, 6 kW) has the capacity to replace two of either the former heaters, this is generally not practical because extensive plumbing changes are required. In applications where one of the two former heaters is to be replaced on the same engine, use a new 7C1710 Heater. If the 7C1710 Heater connections need to be changed to conform to the supply voltage connection, see Illustration 1.
If it is necessary to change the electrical connections on a 7C1709 Heater to conform to the supply voltage, refer to Illustration 2.
Illustration 2. Series and parallel connections for the two heating elements in each 7C1709 Heater.