 |
Description and Operation 03 ENGINE > 03 ENGINE COOLING |
The cooling system contains the High Temperature System (HTS), the Low Temperature System (LTS), and the Driveline Cooling System (DCS).
The three cooling system subassemblies use the same fill point on the coolant reservoir. The full cooling system has a capacity of approximately 29.7 litres, and has a mixture of 50% antifreeze and 50% demineralised water.
The cooling system has an operating range from ambient pressure to 1.8 Bar. The coolant pressure cap opens at 1.8 Bar. The wax thermostat starts to open at 82.5°C and is fully open at 92°C.
Content:
- High Temperature System (HTS)
- Low Temperature System (LTS)
- Water-Air Charge Air Coolers (WACAC)
- Driveline Cooling System (DCS)
- Central Cooling Fan (CFF) module
- Coolant level sensor
- Coolant temperature sensor
- Notes, cautions and warnings
- Notes
- Workshop manual and parts manual references
High Temperature System (HTS):
The HTS is a cooling system for the engine assembly, engine oil, turbo assemblies, and HVAC system.
Fig.1. HTS Schematic:
Fig.2. HTS System:
Heat exchangers connected to the HTS include the HTS central radiator, right side auxiliary radiator, and the engine oil cooler.
The HTS system has two pumps. The first is a mechanical water pump operated by the FEAD belt. The second is an electric pierburg-type run-on pump.
The run-on pump has two functions:
- To make the turbo assemblies cool after engine shutdown.
- To help the Heating, Ventilation and Air Conditioning (HVAC) system during low engine speed.
The run-on pump is controlled by switching supply from the HVAC Module [HVAC] through Body-CAN. The operation of the run-on pump is on or off only.
The run-on pump is set to on when the engine is on. At engine shutdown, the engine management system (EMS) uses the modelled temperature of the turbocharger assemblies to select the correct run-on time. This instruction is sent to the HVAC module, which operates the turbo run-on pump.
The temperature for the turbocharger assemblies is calculated from exhaust temperatures and coolant temperature at engine shutdown.
When the engine is shutdown, the run-on pump operates as follows:
| Modelled turbocharger assembly temp (°C) Run-on time (seconds) | Run-on time (seconds) |
|---|---|
| 199.960 | 0 |
| 499.960 | 600 |
| 799.960 | 1800 |
| 899.960 | 1800 |
Low Temperature System (LTS):
The LTS is a cooling system for the Water-Air Charge Air Coolers (WACAC). Heat exchangers that are connected to the LTS include the LTS central radiator and the left side auxiliary radiator.
Fig.3. LTS Schematic:
Fig.4. LTS System:
The LTS has two electric pump modules (see Notes) which are controlled by Engine Control Module 1 [ECM1] through generator and cooling pumps LIN [ECM-LIN].
The LTS electric pumps are connected to ECM1 through the water pump link harness, forward harness, and the engine harness.
Caution:To calculate when the two LTS pumps must operate, the ECM1 monitors data from the MAF sensor and the TMAP sensor on the intake manifold.
When the vehicle is moving, the inputs that follow are used to set duty cycle of the two LTS pumps:
- The intake manifold air temperature
- The intake manifold airflow
- The ambient air temperature
When the vehicle is stopped, the two LTS pumps operate as follows:
| Engine coolant temperature (°C) | Pump duty (%) |
|---|---|
| 75.0 | 0.0 |
| 90.0 | 0.0 |
| 95.25 | 25.0 |
| 99.75 | 34.9976 |
| 110.25 | 50.0 |
| 120.0 | 50.0 |
Water-Air Charge Air Coolers (WACAC): TO MOVE TO 03.12
The WACAC assemblies are water-cooled type heat exchangers or intercoolers. They remove heat from the air intake system.
Each WACAC assembly has a Temperature and Manifold Absolute Pressure (TMAP) sensor.
The TMAP sensor for the left side WACAC is TMAP2, and this sends data to ECM2 through the engine harness. The TMAP sensor for the right side WACAC is TMAP1, and this sends data to ECM1 through the engine harness.
Driveline Cooling System:
The DCS is a cooling system for the transmission assembly and axle assembly. Heat exchangers that are connected to the DCS include the DCS radiator, and the transmission oil cooler.
Fig.5. DCS Schematic:
Fig.6. DCS System:
Coolant is also supplied to the transmission assembly through a water jacket.
The DCS has one electric pump (see Notes), which is controlled by Engine Control Module 1 [ECM1] through generator and cooling pumps LIN [ECM-LIN]. It is connected to ECM1 through the transmission harness, cabin harness, forward harness, and the engine harness.
The DCS pump operates as follows:
| Off | Variable | On/Full | |
|---|---|---|---|
| Transmission oil temp. | <90°C | <90-100°C | >100°C |
| Axle oil temp. | <130°C | <130-150°C | >150°C * |
* Operation is the same after engine shutdown.
The temperature sensor for the transmission oil, and the temperature sensor for the axle oil send data to ECM1. They are connected to ECM1 through the transmission harness, cabin harness, forward harness, and the engine harness.
See 07-00 Transmission for more information.
Central Cooling Fan (CFF) module:
There is a single 515 mm diameter cooling fan module. This has a 1000w motor, which is controlled by ECM1 through generator and cooling pumps LIN [ECM-LIN].
The CCF module is connected to ECM1 through the forward harness and the engine harness.
The CCF module operates as follows:
| Off | Variable | On/Full | |
|---|---|---|---|
| Engine coolant temp. | <95°C, and/or vehicle speed ≥120mph. | 95-102°C | >102°C, and vehicle speed <120mph. * |
| WACAC air outlet temp. | ≤40°C, and/or vehicle speed ≥120mph. | 40-60°C | - |
| Transmission oil temp. | <90°C, and/or vehicle speed ≥120mph. | 90-120°C | >120°C, and vehicle speed <120mph. |
| Axle oil temp. | <140°C, and/or vehicle speed ≥120mph. | 140-175°C | >175°C, and vehicle speed <120mph. * |
*Operation is the same after engine shutdown.
Coolant level sensor:
The location of the engine coolant level sensor is in the middle of the coolant reservoir. It is connected to the body controller front [BC_F] module through the forward harness, cabin harness and fascia harness.
Coolant temperature sensor:
The location of the coolant temperature sensor is at the top of the thermostat housing. It is connected to engine control module 1 [ECM1] through the engine harness.
Notes, cautions and warnings:
You must obey the notes, cautions and warnings in the workshop manual, where applicable, as these contain very important information.
Workshop manual and parts manual references:
- 03 Engine > 03 Engine Cooling
- 07 Transmission > 02 Transmission Cooling