+2 for the fans being the cause of the problem. The fan/shroud design on the VT/VX is very efficient, and if the fans are coming on at the correct temperature trigger, they will keep your engine at its design temperature in almost any ambient temperature (within reason). Note that you don't need to do anything special about bleeding the air from the cooling system of a GenIII/LS1, this happens automatically, just make sure that the level in the expansion tank is maintained at the correct level. Some information on electrical fans FYI:
"ELECTRIC COOLING FANS
The GEN III engine has two, two speed electric engine cooling fan assemblies that provide the primary means of moving air through the engine radiator. The cooling fans are used to cool engine coolant flowing through the radiator and the refrigerant flowing through the A/C condenser (if fitted).
Each engine cooling fan motor has four terminals; two negative and two positive. The two negative terminals are the relay controlled circuits for fan operation. The two positive terminals are the direct power feed from a fusible link to the fan motors. When an earth signal is applied to one of the negative terminals, the fan motor will operate at low speed. When an earth signal is applied to both negative terminals, both fans will operate at high speed.
The engine cooling fan high speed and low speed relays are used to control the earth signal to the electric motors. The high speed relay is controlled by the PCM, which controls the earth path for the engine cooling fan high speed relay. The low speed of the electric fan is controlled by the PCM through a special Data Communication to the BCM. The BCM controls the earth path for the engine cooling fan low speed relay.
The PCM determines operation of the two, two speed engine cooling fans based on A/C request, engine coolant temperature, A/C Refrigerant Pressure Transducer, and vehicle speed signal inputs.
There are also four (4) suppression capacitors incorporated into the fan motor wiring circuits. These suppression capacitors help eliminate fan motor noise through the radio speakers. If these capacitors are open, then noise will be present through the radio speakers. If shorted to earth, the fan motors could continuously run, or the fuse or fusible link could fail.
ENGINE COOLING FAN LOW SPEED
The engine cooling fan low speed relay is energised by the BCM. The PCM determines when to enable the low speed fan based on inputs from the BCM serial data, Engine Coolant Temperature (ECT) sensor and the Vehicle Speed Sensor (VSS). The cooling fan low speed relay will be turned ON when:
. The A/C request indicated (YES) and either
. the vehicle speed is less than 30 km/h
or
.A/C pressure is greater than 1500 kPa
or
. The coolant temperature is greater than 98°C.
. If the coolant temperature is greater than 113°C when the ignition is switched OFF, the relay is energised for up to approximately four minutes.
. If an engine coolant temperature sensor fault is detected, such as DTC P0117, P0118, P1114, P1115.
The cooling fan low speed relay will be turned OFF when any of the following conditions have been met:
. The A/C request is not indicated (NO)
. The A/C request is indicated (YES) and the vehicle speed is greater than 50 km/h, A/C pressure is less than 1170 kPa, and coolant temperature less than 98°C.
NOTE: The low speed cooling fan has a minimum, run on time of 30 seconds.
ENGINE COOLING FAN HIGH SPEED
The engine cooling fan high speed relay is controlled by the PCM based on input from the Engine Coolant Temperature (ECT) sensor. The PCM will only turn ON the engine cooling fan high speed relay fan if the engine cooling fan low speed relay has been ON for 2 seconds and the following conditions are satisfied:
. An Engine Coolant Temperature sensor fault is detected such as DTC P0117, P0118, P1114, P1115.
. Coolant temperature greater than 108°C.
The engine cooling fan high speed relay can also be enabled by the A/C Refrigerant Pressure Transducer. When the A/C Refrigerant Pressure transducer determines the A/C system pressure is too high (greater than 2400 kPa) and this will instruct the PCM to enable the high speed fan.
If the low speed fan was OFF when the criteria was met to turn the high speed fan ON, the high speed fan will come ON 5 seconds after the low speed fan is turned ON.
If both the engine cooling fan relays are ON, the PCM will turn OFF the high speed relay when:
. The engine coolant temperature is less than 102°C.
. A/C request not indicated (NO).
. A/C request indicated (YES) and A/C pressure is less than 1900 kPa.
NOTE: The high speed cooling fan has a minimum, run on time of 30 seconds."
