TUBE AS 4639044 - Caterpillar

General Information
Illustration 1 g01511713
(1) Fuel line
(2) Hydraulic oil heater
(3) Shut off valve at rear of engine
(4) Preheater
(5) Cab heater The machine preheater will preheat the engine, the cab and the hydraulic oil in the hydraulic tank prior to machine operation. This system will warm the engine, the cab and the hydraulic oil by heating the coolant to the engine, to the cab heater and the heat exchanger in the hydraulic tank before engine start-up. Warming a cold engine before start-up extends the service life of the engine. Warming the hydraulic oil improves the flow to the hydraulic components. Since the machine preheater operates on diesel fuel and 24 volt power the unit is able to operate independently from the engine. The unit will regulate the coolant temperature between 65 °C (150 °F) and 85 °C (185 °F) by automatically cycling the heater.Use the on/off switch or the timer in order to activate the machine preheater.Reference: For additional information on setting the timer, refer to Operation and Maintenance Manual, "Engine and Cab Preheat System".The machine preheater is equipped with following safety devices:
Flame sensor
Temperature sensor
Safety sensor (overheating)Heater (Start-Up)
The following sequence will occur after the machine preheater is activated:
The control unit will perform a system check.
The water pump will begin circulating coolant.
The combustion air fan will activate.
The glow plug heats up.
The fuel metering pump activates.
The combustion air fan increases speed.
After the ignition of the machine preheater, the flame sensor will alert the control unit. The control unit will then deactivate the glow plug. (Ignition time is 1.5 to 2 minutes.)Heater Operation
The following operations will take place after a successful ignition:
The machine preheater will operate in high heat mode. The temperature is monitored at the heat exchanger.
If the coolant temperature is 85 °C (185 °F), the machine preheater is automatically switched to the low heat mode.
If the coolant temperature drops below 75 °C (167 °F), the machine preheater is automatically switched to the high heat mode.
If the coolant temperature is above 86 °C (187 °F), then the machine preheater is automatically shut down.
The coolant pump will continue to circulate coolant in order to allow the machine preheater to monitor engine temperature.
The machine preheater will automatically restart once the coolant temperature reaches 75 °C (167 °F).
The machine preheater continues to operate. The following conditions will turn off the machine preheater. The machine preheater is manually shut down. The timer times out. The machine preheater is shut down due to a malfunction.Note: A malfunction of the burner flame will shut down the machine preheater. The machine preheater will automatically attempt one restart. If the restart is successful, the machine preheater will continue to operate. If the restart is not successful, the machine preheater will shut down completely with a cool down cycle.Note: During operation, the machine preheater will continually sense the input voltage from the battery. If the input voltage falls below a certain voltage or if the input voltage raises above a certain voltage, the machine preheater will automatically shut down with a cool