Engine Cooling System & Automatic Transmission Cooling System: Overview Dodge Caliber I

Scheme 1

The cooling system regulates engine operating temperature. It allows the engine to reach normal operating temperature as quickly as possible, maintains normal operating temperature and prevents overheating.

The cooling system also provides a means of heating the passenger compartment. The cooling system is pressurized and uses a centrifugal water pump to circulate coolant throughout the system. Gas engines use a separate and remotely mounted, ambient pressure coolant recovery bottle using a pressure/vent cap. Diesel engine use a separate and remotely mounted, pressurized coolant tank using a pressure/vent cap.

The cooling system consists

1. Radiator
2. Coolant
3. Electric Cooling Fans
4. Water pump
5. Dual Thermostats (Gas Engines)
6. Charge air cooler (Turbocharged vehicles only)
7. Hoses and clamps
8. Transmission oil cooler
9. Coolant pressure bottle/overflow system

Scheme 2

The water pump draws coolant from the radiator and delivers it to the engine block. The coolant travels through the engine block into the cylinder head. Coolant exits the engine at the thermostat. If the coolant temperature is less than 87°C (189°F) the thermostat directs all of the coolant back to the water pump. If the coolant temperature is between 87°C (189°F) and 102°C (216°F) the thermostat is in the mix mode and directs the coolant to the radiator and the water pump. If the coolant is greater than 102°C (216°F), the thermostat directs all of the coolant to the radiator.

The thermostat also feeds excess coolant and bleeds air from the system through a hose leading to the coolant reservoir. The reservoir returns coolant to the inlet side of the water pump. A port and hose at the rear of the engine block provides coolant to the heater core. This coolant is returned to the engine at the intake side of the water pump.

The oil cooler receives coolant directly from the engine block. A hose returns this coolant to the inlet side of the water pump.

DESCRIPTION

The automatic belt tensioner maintains proper tension on the accessory drive belt. The tensioner pulley can be serviced separately.

Scheme 3

1. Raise vehicle on hoist.
2. Remove belt splash shield (3). 1 - POWER STEERING PUMP 2 - ACCESSORY DRIVE BELT 3 - GENERATOR 4 - CRANKSHAFT PULLEY 5 - LOWER IDLER PULLEY 6 - CRANKSHAFT PULLEY 7 - WATER PUMP PULLEY 8 - ACCESSORY DRIVE BELT TENSIONER 9 - UPPER IDLER PULLEY
3. Remove accessory drive belt. See «REMOVAL»(ref-284880-S41589349752008051600000) .
4. Remove accessory drive belt tensioner mounting bolt. Remove accessory drive belt tensioner (8).

COOLANT-OPERATION

Coolant flows through the engine block absorbing the heat from the engine, then flows to the radiator where the cooling fins in the radiator transfers the heat from the coolant to the atmosphere. During cold weather the ethylene-glycol or coolant prevents water present in the cooling system from freezing within temperatures indicated by mixture ratio of coolant to water.

OPERATION

The block heater element is inserted into a bore in the engine block. When electrical power (110 volt A.C.) is applied to the element, it creates heat. This heat is transferred to the aluminum engine block. This provides easier engine starting and faster warm-up when vehicle is operated in areas having extremely low temperatures.

The ECT sensor provides an input to the PCM. As temperature increases, resistance of the sensor decreases. As coolant temperature varies, the ECT sensor resistance changes resulting in a different voltage value at the PCM ECT sensor signal circuit. The ECT sensor provides input for various PCM operations. The PCM uses the input to control air-fuel mixture, timing, and radiator fan on/off times.

When the Engine is cold and both the primary and secondary thermostats are closed. The coolant will circulate through the engine, heater system, and the bypass. The cooling system has no flow through the radiator

As the engine warms up, the primary thermostat will start to open at 82°C (179°F). Coolant will start to flow through the radiator oil cooler and transmission cooler. Coolant will flow through the transmission oil cooler only when the primary thermostat is fully open. The primary thermostat will fully open at 95°C (203°F).

The secondary thermostat will start to open at 95°C (203°F). This will increase the coolant flow through the cylinder block and cylinder head and the radiator. The secondary thermostat will fully open at 110°C (230°F).

If the thermostat is stuck open or allows coolant leakage through it, the engine will not operate at the proper temperature for obtaining engine fuel efficiency, performance and emissions levels. If this condition occurs, a diagnostic trouble code will be set and a MIL light will be turned on. Refer to the Powertrain Diagnostic article for further information and diagnostics provided.

The radiator cooling fans are dual-speed electric motor driven fans. The radiator fan assembly includes two electric motors, two five blade fans, and a support shroud that is attached to the radiator. The radiator fans are serviced as an assembly.

The radiator is a cross-flow type (horizontal tubes) with design features that provide greater strength, as well as sufficient heat transfer capabilities to keep the engine coolant within operating temperatures.

The radiator has an aluminum core with plastic tanks. Although stronger than brass, plastic tanks are subject to damage by impact. Always handle radiator with care.

The radiator functions as a heat exchanger, using air flow across the exterior of the radiator tubes. This heat is then transferred from the coolant and into the passing air.

Scheme 4

Note. It is not necessary to discharge the air conditioning system to remove the radiator.

1. Disconnect negative battery cable.
2. Remove engine cover. Refer to «REMOVAL»(ref-284871-S09296108772008051600000) .
3. Remove air cleaner housing assembly. Refer to «REMOVAL»(ref-284871-S18001259912008051600000) .
4. Raise vehicle on hoist.
5. Drain cooling system. See «STANDARD PROCEDURE»(ref-284880-S27432255532008051600000) .
6. Disconnect radiator fan motor electrical connector.
7. Disconnect lower radiator hose.
8. Remove two lower fasteners attaching radiator fan shroud to radiator.
9. Disconnect Charger Air Cooler hoses from Charge Air Cooler.
10. Disconnect Charger Air Cooler from radiator.
11. Lower vehicle.
12. Remove grille.
13. Remove upper radiator hose from the radiator.
14. Remove remaining fasteners attaching radiator fan shroud to radiator.
15. Remove radiator fan/shroud assembly.
16. Remove remaining fasteners attaching AC condenser to radiator. Reposition AC condenser.
17. Unclip Charge Air Cooler from radiator remove radiator assembly by lifting it up from the engine compartment. Care should be taken not to damage the cooling fins and tubes during removal.

Scheme 5

1. Drain cooling system. See «STANDARD PROCEDURE»(ref-284880-S27432255532008051600000) .
2. Remove radiator fan. See «REMOVAL»(ref-284880-S30375390742008051600000) .
3. Disconnect lower radiator hose.
4. Remove fasteners attaching AC condenser to radiator. Reposition AC condenser.
5. Remove radiator assembly by lifting it up from the engine compartment. Care should be taken not to damage the cooling fins and tubes during removal.