Always Allow the Engine to Reach Normal Operating Temperature
Damage to valves and components during operation in very cold temperature conditions can result from engine operation for short intervals. Damage to the engine can occur from starting the engine and stopping the engine many times without allowing the engine to reach normal operating temperature. The fuel and the oil are not completely burned in the combustion chambers while the engine is operating below the normal operating temperature. This fuel and oil causes soft carbon deposits on the valve stems. Generally, these deposits do not cause problems because these deposits are burned off during operation at normal engine temperatures. When the engine is started and the engine is stopped frequently the engine may not reach the normal operating temperature. This will cause the carbon deposits to become thicker. This will prevent the free operation of the valves. This can also cause the following conditions: valves to stick, pushrods to bend and other damage to valve train components. Begin operating the engine at low load. After the engine oil pressure is normal and the coolant temperature begins to rise, the engine may be operated at full load. Allow the engine to reach normal operating temperature. This will keep the carbon deposits on the valve stems at a minimum. This will also maintain free operation of the valves and the valve train components. The engine will remain in better condition and the service life of the engine may be extended when the engine is warmed up properly. Lubrication will be improved, with less acid and sludge in the oil. This will give longer service life for the engine bearings, the piston rings, and other parts. However, limit unnecessary idle time to ten minutes. Engine wear is greatest at low idle and unnecessary idling wastes fuel.
Engine Block Heaters
A block heater can improve the startability and a block heater can reduce the warm up time by heating the coolant that surrounds the combustion chambers. An electric block heater can be activated immediately after the engine is stopped. The use of a block heater will reduce the temperature that would require a starting aid. An effective block heater is typically a 1250/1500 W unit. Contact your truck dealer for more information.
On/Off Fan Clutch
For better control of the operation of the fan, an ON/OFF fan clutch may be used. ON/OFF fan clutches can help prevent excessive cooling in cold weather. Often, a viscous fan drive will rotate continuously in cold weather. Fan clutches that keep the fan stationary in the OFF position reduce unnecessary movement of air in order to help maintain adequate engine operating temperatures. NOTE: For some engines, if a viscous fan drive must be specified, select a "slow speed" viscous fan drive that turns the fan at 200 to 250 rpm at engine idle speed. Contact your OEM dealer for more information.
Bypass Valves and Insulated Heater Lines
The coolant must be able to bypass the radiator in order to help prevent cooling the engine excessively during periods of operation at light loads. Coolant that passes through the radiator must be minimized in order to maintain the engine operating temperature in cold weather. A valve that will allow air flow but not coolant flow can prevent the engine from being cooled excessively. These valves will prevent the coolant from flowing around the thermostat and through the radiator. For very cold climates, insulated cab heater lines are also beneficial. Insulated cab heater lines will provide more available heat from the coolant to the cab and less heat will be lost to the outside air.
Insulated Air Intake and Cab Insulation
An air cleaner that is located under the hood may be specified when temperatures that are below −18 °C (0 °F) are frequently encountered. This is sometimes referred to as a Snow Valve. An air cleaner that is located under the hood may also minimize the amount of snow that gets packed into the air cleaner. Heat that is rejected by the engine through the convection can warm the intake air. Additional heat can be retained around the engine by specifying additional insulation for the cab and additional insulation for the hood when the truck is ordered. This will improve the comfort of the operator in certain situations when the engine must be kept at an idle overnight.
Winter Fronts, Shutters and Winter Backs
With the introduction of air-to-air aftercooling, the use of winter fronts or shutters for normal operating conditions that are above freezing requires caution to avoid high intake and high exhaust temperatures. The restriction in air flow can cause higher exhaust temperatures, power loss, excessive fan usage and a reduction in fuel economy. However, winter fronts and shutters are useful in maintaining minimum engine coolant temperatures when outside air temperatures drop below freezing. If the engine coolant temperature is above the minimum of 82 °C (180 °F), a winter front is not needed even with cold ambient temperatures.
Note: Caterpillar recommends installing an alarm for a high inlet manifold air temperature when a winter front or a radiator shutter is used. The alarm will warn the operator if the inlet air temperature exceeds 66 °C (150 °F). The operator needs to be warned because of power loss and potential engine damage. An 4W-2682 Temperature Indicator for the inlet manifold is available from Caterpillar for all engines except 3116.
Normally, a winter front must have an opening in order to permit air flow through the winter front. The opening should be circular or the opening should be shaped as a diamond. The opening should be directly in line with the fan hub. Openings for winter fronts are shown in Table 1.
| Openings for Winter Fronts | |
| Temperature | Size of Opening |
| Above 1 °C (34 °F) |
Winter Fronts should be opened or removed. |
−18 °C (0 °F) to 0 °C (32 °F) |
770 cm2 (120 in2) (1) |
−29 °C (−20 °F) to −18 °C (0 °F) |
230 cm2 (36 in2) (2) |
−29 °C (−20 °F) to −34 °C (−29 °F) |
102 cm2 (16 in2) |
| Less than −34 °C (−29 °F) |
No opening is necessary. |
| ( 1 ) | The minimum opening is 385 cm2 (60 in2) for 3116 engines. |
| ( 2 ) | The minimum opening is 193 cm2 (30 in2) for 3116 engines. |
The temperature of the coolant should be monitored by gauges. Monitoring the gauges will ensure that the engine does not overheat when the winter front is used on the vehicle. Winter fronts are generally less expensive than radiator shutters. The radiator shutter thermostat should open the radiator shutters at a temperature that is 5 °C (10 °F) less than the opening temperature of the engine thermostat. If the truck is a cabover style, a winter back that is an air dam for the rear of the cab may be used in addition to a winter front. This will help to maintain the temperature of the engine compartment, especially if the engine will be idling overnight.
Exhaust Restrictors and BrakeSavers
Exhaust restrictors apply a load to the engine in order to provide reduced warm-up time and a reduction in white smoke at start-up. When extended idling periods are unavoidable, the exhaust restrictor can help maintain acceptable coolant temperatures above 82 °C (180 °F). A 6I-0799 Exhaust Restrictor is available from Caterpillar for use on the 3406 Truck Engine. In addition to a primary application as an engine brake, the Caterpillar BrakeSaver can also be used to load the engine in order to maintain acceptable coolant temperatures while the engine is idling. With an exhaust restrictor or a BrakeSaver, the PTO engine governor on an electronically controlled engine or the hand throttle on a mechanically controlled engine can be used to elevate the low idle in order to obtain an engine speed that is near 1000 rpm after the load is applied.