GEAR 3589117 - Caterpillar

All Engines Equipped With 5N5739 Or 5N5740 Jacket Water HeatersReduced life and failure of jacket water heaters can normally be traced to incorrect installation or incorrect electrical hookup. The major problem areas and ways to avoid them are as follows.
Hose Installation
The installation or routing of hoses is most often the cause of jacket water heater problems. The hose routing can be incorrect due to original installation, movement of hoses during repair, or rerouting of hoses around other equipment. Illustrations 1 and 2 show examples of correct and incorrect hose routing.
Illustration 1. Correct hose routing.
Illustration 2. Incorrect hose routing.Both the inlet and the outlet hoses must slope upward from the heater connection to the engine connection for proper circulation to occur. This is especially important on the heater outlet hose. Any loop or high point in the heater outlet hose can result in a steam pocket that will stop all coolant circulation.
Thermostat Failure
Poor coolant circulation, incorrect voltage, and poor electrical connections are all potential problem areas that can shorten thermostat life. Poor coolant circulation can be caused by incorrect hose installation or a restriction in one of the hoses. Poor circulation will cause the thermostat to turn off and on rapidly. If the thermostat turns off and on more than once every 15 minutes its life will be shortened.
A voltage 20% or more above the rated voltage will shorten the service life of the thermostat and the heater element because too much current will pass through them. Make sure that 120 volt jacket water heaters are connected to a 120 volt source and that 240 volt jacket water heaters are connected to a 240 volt source.
Poor electrical connections can cause the thermostat to overheat and fail. This is more likely to occur with a 120 volt jacket water heater. Use No. 10 wire when connecting 120 volt jacket water heaters. Use 2L8066 Insulated Terminals or similar crimp-type terminals. It is recommended that all connections be soldered so they stay tight.
Heater Element Failure
Short service life of heater elements is normally due to excessive voltage or a lack of coolant around the element. The 240 volt elements have a resistance of approximately 19.2 ohms. The 120 volt elements have a resistance of approximately 4.8 ohms. Connecting a jacket water heater to a voltage supply that is 20% or more above the rated voltage will shorten the service life of the heater elements and also the thermostats.
If a jacket water heater is connected before it is filled with coolant, failure of the element will occur almost immediately. Make sure that jacket water heaters are filled with coolant before they are connected.
Insufficent Heating
The most common cause of insufficient heating of the engine block is due to incorrect hose installation and is described in the section "Hose Installation". Rapid thermostat cycling would indicate incorrect hose installation.
Low supply voltage will reduce heating. If voltage is 20% below the rated voltage, the power (wattage) is 36% below the rated wattage. Small reductions in voltage due to