Ingersoll-Rand Thermo King SGCM 4000, Maintenance Manual, Page: 131 / 181

Engine Maintenance
130
8. Refill the radiator with the 50/50 antifreeze mixture and make sure to bleed the air from the cooling
system as needed.
Bleeding Air from the Cooling System
Normally, all but about 1.5 qt (1.4 liters) of coolant drain out of the cooling system when it is drained. If
approximately half of the Cooling System Capacity (see Specifications Chapter) seems to fill the cooling
system after it has been drained, air has been trapped in the block. Bleed the air out of the block using the
following procedure:
NOTE: If an engine runs with air trapped in the block, the engine may be damaged. The high water
temperature switch may not protect an engine that has air trapped in the block, because the high water
temperature switch is designed to protect an engine from overheating due to failures in the cooling
system.
1. Slowly pour the coolant into the expansion tank until it appears to be full.
2. Make sure that the amount of coolant that goes back into the system is approximately equal to the
amount of coolant that came out of the system.
3. Start the engine. Monitor the coolant temperature with the unit engine coolant temperature gauge, or
by using a non-contact thermometer pointed at the thermostat housing in the location of the high
water temperature switch or sensor. When the temperature reaches 150 F (66 C), shut the engine off
for 2 minutes. This allows time for the thermostat to heat soak and open fully, ensuring that any
remaining air will be purged out of the engine block when the engine is restarted.
4. Restart the engine and run it in low speed. Remove the cap from the expansion tank and slowly pour
coolant into expansion tank until it is full, then reinstall the expansion tank cap.
5. Repeat steps 3 and 4 until the coolant level stabilizes.
Engine Thermostat
Thermostat is molded in the water outlet box.
Coolant Level Switch
The coolant level switch is a float and needs to be positioned correctly. The notch needs to be in the 6
o’clock position when mounted in the tank.
Figure 53: Notch Position
CAUTION: Do not start the engine without bleeding the air out of the block.