Engine Cooling System & Automatic Transmission Cooling System: Overview Dodge Durango II рестайлинг

Scheme 3

Scheme 4

The cooling system consists of

1. Radiator
2. Cooling fan
3. Thermal viscous fan drive
4. Fan shroud
5. Radiator pressure cap
6. Thermostat
7. Coolant Recover container
8. Transmission oil cooler
9. Water pump
10. Hoses and hose clamps

COOLING - OPERATION

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

The cooling system also provides a means of heating the passenger compartment and cooling the automatic transmission fluid (if equipped). The cooling system is pressurized and uses a centrifugal water pump to circulate coolant throughout the system.

ACCESSORY DRIVE BELT - DESCRIPTION

The accessory drive belt is a serpentine type belt. Satisfactory performance of these belts depends on belt condition and proper belt tension.

Scheme 5

When diagnosing serpentine accessory drive belts, small cracks that run across the ribbed surface of the belt from rib to rib, are considered normal. These are not a reason to replace the belt. However, cracks running along a rib (not across) are not normal. Any belt with cracks running along a rib must be replaced. Also replace the belt if it has excessive wear, frayed cords or severe glazing.

Refer to ACCESSORY DRIVE BELT DIAGNOSIS CHART for further belt diagnosis.

ACCESSORY DRIVE BELT TENSIONER - OPERATION

The automatic belt tensioner maintains belt tension by using internal spring pressure, a pivoting arm and pulley to press against the drive belt.

Scheme 6

On 4.7L engines, the tensioner (3) is equipped with an indexing tang on back of tensioner and an indexing stop on tensioner housing. If a new belt is being installed, tang must be within approximately 24 mm (.94 inches) of indexing stop. Belt is considered new if it has been used 15 minutes or less.

If the above specification cannot be met, check for

1. The wrong belt being installed (incorrect length/width)
2. Worn bearings on an engine accessory (A/C compressor, power steering pump, water pump, idler pulley or generator)
3. A pulley on an engine accessory being loose
4. Misalignment of an engine accessory
5. Belt incorrectly routed.

Note. A used belt should be replaced if tensioner indexing arrow has moved to the minimum tension indicator. Tensioner travel stops at this point.

1. Remove accessory drive belt. See «REMOVAL»(ref-285336-S24335394222008052100000) .
2. Remove tensioner assembly from mounting bracket (1). WARNING: Because of high spring pressure, do not attempt to disassemble automatic tensioner. Unit is serviced as an assembly except for pulley on tensioner.
3. Remove pulley bolt. Remove pulley from tensioner.

Scheme 7

1. Remove accessory drive belt. See «REMOVAL»(ref-285336-S24335394222008052100000) .
2. Remove tensioner and mounting bracket.
3. Remove the tensioner assembly from the mounting bracket.

COOLANT - DESCRIPTION - HOAT

The cooling system is designed around the coolant. The coolant must accept heat from engine metal, in the cylinder head area near the exhaust valves and engine block. Then coolant carries the heat to the radiator where the tube/fin radiator can transfer the heat to the air.

The use of aluminum cylinder blocks, cylinder heads, and water pumps requires special corrosion protection. Mopar® Antifreeze/Coolant, 5 Year/100, 000 Mile Formula (MS-9769), or the equivalent ethylene-glycol base coolant with organic corrosion inhibitors (called HOAT, for Hybrid Organic Additive Technology) is recommended. This coolant offers the best engine cooling without corrosion when mixed with 50% ethylene-glycol and 50% distilled water to obtain a freeze point of -37°C (-35°F). If it loses color or becomes contaminated, drain, flush, and replace with fresh properly mixed coolant solution.

COOLANT - OPERATION

Coolant flows through the engine block, cylinder head, 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 propylene-glycol coolant prevents water present in the cooling system from freezing within temperatures indicated by mixture ratio of coolant to water.

COOLANT RECOVERY CONTAINER - DESCRIPTION

The coolant recovery container is integral to the windshield reservoir and is made of high temperature plastic.

COOLANT RECOVERY CONTAINER - OPERATION

The coolant recovery container works in conjunction with the radiator pressure cap. It utilizes thermal expansion and contraction of coolant to keep coolant free of trapped air. It provides a volume for expansion and contraction of coolant. It also provides a convenient and safe method for checking coolant level and adjusting level at atmospheric pressure. This is done without removing the radiator pressure cap. The system also provides some reserve coolant to the radiator to cover minor leaks and evaporation or boiling losses.

As the engine cools, a vacuum is formed in the cooling system of both the radiator and engine. Coolant will then be drawn from the coolant tank and returned to a proper level in the radiator.

ENGINE BLOCK HEATER - OPERATION

The heater warms the engine coolant providing easier engine starting and faster warm-up in low temperatures. Connecting the power cord to a grounded 110-120 volt AC electrical outlet with a grounded three wire extension cord provides the electricity needed to heat the element.

ENGINE COOLANT TEMPERATURE SENSOR - DESCRIPTION

The Engine Coolant Temperature (ECT) sensor is used to sense engine coolant temperature. The sensor protrudes into an engine water jacket.

The ECT sensor is a two-wire Negative Thermal Coefficient (NTC) sensor. Meaning, as engine coolant temperature increases, resistance (voltage) in the sensor decreases. As temperature decreases, resistance (voltage) in the sensor increases.

ENGINE COOLANT TEMPERATURE SENSOR - OPERATION

At key-on, the Powertrain Control Module (PCM) sends out a regulated 5 volt signal to the ECT sensor. The PCM then monitors the signal as it passes through the ECT sensor to the sensor ground (sensor return).

When the engine is cold, the PCM will operate in Open Loop cycle. It will demand slightly richer air-fuel mixtures and higher idle speeds. This is done until normal operating temperatures are reached.

The PCM uses inputs from the ECT sensor for the following calculations

1. for engine coolant temperature gauge operation through CCD or PCI (J1850) communications
2. Injector pulse-width
3. Spark-advance curves
4. ASD relay shut-down times
5. Idle Air Control (IAC) motor key-on steps
6. Pulse-width prime-shot during cranking
7. O2 sensor closed loop times
8. Purge solenoid on/off times
9. EGR solenoid on/off times (if equipped)
10. Leak Detection Pump operation (if equipped)
11. Radiator fan relay on/off times (if equipped)
12. Target idle speed

Scheme 8

The Engine Coolant Temperature (ECT) sensor (1) on the 4.7L engine is located near the front of the intake manifold.

1. Partially drain the cooling system. See «STANDARD PROCEDURE»(ref-285336-S41920237022008052100000) .
2. Disconnect the electrical connector from the ECT sensor (1).
3. Remove the sensor (1) from the intake manifold.

Scheme 9

The Engine Coolant Temperature (ECT) sensor (3) on the 3.7L engine is installed into a water jacket at front of intake manifold near rear of generator.

1. Partially drain the cooling system. See «STANDARD PROCEDURE»(ref-285336-S41920237022008052100000) .
2. Disconnect the electrical connector from the sensor (3).
3. Remove the sensor from the intake manifold.

Scheme 10

The Engine Coolant Temperature (ECT) sensor (3) on the 5.7L engine is located under the air conditioning compressor. It is installed into a water jacket at the front of the cylinder block.

1. Partially drain the cooling system. See «STANDARD PROCEDURE»(ref-285336-S41920237022008052100000) .
2. Remove accessory drive belt. See «REMOVAL»(ref-285336-S24335394222008052100000) .
3. Carefully unbolt air conditioning compressor from front of engine. Do not disconnect any A/C hoses from compressor. Temporarily support compressor to gain access to ECT sensor (3).
4. Disconnect electrical connector (2) from sensor (3).
5. Remove sensor (3) from cylinder block.

Scheme 11

1. Apply thread sealant to sensor threads.
2. Install engine coolant sensor into intake manifold. Tighten sensor to 27 N.m (20 ft. lbs.) torque.
3. Connect the electrical connector.
4. Fill the cooling system. See «STANDARD PROCEDURE»(ref-285336-S41920237022008052100000) .

Scheme 12

1. Apply thread sealant to sensor threads.
2. Install ECT sensor (3) to engine.
3. Tighten sensor to 11 N.m (97.3 in. lbs.) torque.
4. Connect electrical connector (2) to ECT sensor (3).
5. Fill the cooling system. See «STANDARD PROCEDURE»(ref-285336-S41920237022008052100000) .

Scheme 13

1. Apply thread sealant to sensor threads.
2. Install ECT sensor (1) to engine.
3. Tighten sensor to 27 N.m (20 ft. lbs.) torque.
4. Connect electrical connector to sensor (1).
5. Fill cooling system. See «STANDARD PROCEDURE»(ref-285336-S41920237022008052100000) .

Scheme 14

Scheme 15

The thermostat on the 5.7L gas powered engine is located beneath the thermostat housing (1) at the front of the intake manifold.

On the 3.7L/4.7L engine the thermostat (4) is designed to block the flow of the coolant bypass journal by 50% instead of completely blocking the flow.

The thermostat is a wax pellet driven, reverse poppet choke type.

Coolant leakage into the pellet container will cause the thermostat to fail in the open position. Thermostats very rarely stick. Do not attempt to free a thermostat with a prying device.

The same thermostat is used for winter and summer seasons. An engine should not be operated without a thermostat, except for servicing or testing. Operating without a thermostat causes longer engine warm up time, unreliable warm up performance, increased exhaust emissions and crankcase condensation that can result in sludge formation.

ENGINE COOLANT THERMOSTAT - OPERATION

The wax pellet is located in a sealed container at the spring end of the thermostat. When heated, the pellet expands, overcoming closing spring tension and water pump pressure to force the valve to open.

RADIATOR - DESCRIPTION

The radiator is a aluminum vertical-flow design with vertical tubes through the radiator core and plastic top and bottom tanks.

RADIATOR - OPERATION

The radiator supplies sufficient heat transfer using the cooling fins interlaced between the horizontal tubes in the radiator core to cool the engine.

RADIATOR PRESSURE CAP - OPERATION

A vent valve in the center of the cap will remain shut as long as the cooling system is pressurized. As the coolant cools, it contracts and creates a vacuum in cooling system. This causes the vacuum valve to open and coolant in reserve/overflow tank to be drawn through connecting hose into radiator. If the vacuum valve is stuck shut, or overflow hose is kinked, radiator hoses will collapse on cool-down.

WATER PUMP - OPERATION

A centrifugal water pump circulates coolant through the water jackets, passages, intake manifold, radiator core, cooling system hoses and heater core, this coolant absorbs the heat generated when the engine is running. The pump is driven by the engine crankshaft via a drive belt.

WATER PUMP - OPERATION - WATER PUMP BYPASS - 4.7L

When the thermostat is in the closed position the bypass gallery is not obstructed allowing 100% flow. When the thermostat is in the open position the pill partially covers the bypass hole, reducing the amount of bypass flow. This design allows the coolant to reach operating temperature quickly when cold, while adding extra cooling during normal temperature operation.