Cooling System - Engine & Transmission: Overview RAM Pickup 2500

Scheme 1

The 3.7L/4.7L engine cooling system consists of

1. LH Cylinder Head (1)
2. Bleed (2)
3. Thermostat location (3)
4. RH Cylinder Head (4)
5. RH Bank Cyl. Block (5)
6. LH Bank Cyl. Block (6)
7. Coolant Temp Sensor (7)
8. From Heater Core (8)
9. To Heater Core (9)

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.

Scheme 2

The 5.7L engine cooling system consists of

1. LH Cylinder Head (1)
2. To Radiator (2)
3. From Radiator (3)
4. To RH Cylinder Head (4)

The cooling system 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 through the system. The coolant recovery/reserve system utilizes an ambient overflow bottle.

Scheme 3

The diesel engine cooling system consists of

1. Cross-flow radiator
2. Belt driven water pump
3. Belt driven Electronically Controlled Viscous fan drive (Diesel Engine)
4. Engine mounted fan shroud
5. Radiator pressure cap
6. Vertically mounted thermostat
7. Coolant reserve/recovery system
8. Transmission Oil Cooler (Automatic Transmission Only)
9. Engine mounted Transmission oil cooler
10. Radiator mounted fan shroud
11. EGR Cooler
12. Turbocharger Actuator

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 source of hot coolant for 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.

1. When engine is cold the thermostat is closed. The cooling system has no flow through the radiator. The coolant flows through the engine, water pump, and heater.
2. When engine is warm the thermostat is full open. One the gas engine coolant flows through the engine, radiator, heater, and water pump.

All engines utilize an ambient overflow bottle for coolant recovery/reserve.

An optional factory installed maximum duty cooling package is available on most models. This package will provide additional cooling capacity for vehicles used under extreme conditions such as trailer towing in high ambient temperatures.

DESCRIPTION

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

Correct drive belt tension is required to ensure optimum performance of the belt driven engine accessories. If specified tension is not maintained, belt slippage may cause; engine overheating, lack of power steering assist, loss of air conditioning capacity, reduced generator output rate, and greatly reduced belt life.

It is not necessary to adjust belt tension. All engines are equipped with an automatic belt tensioner. The tensioner maintains correct accessory drive belt tension at all times.

Scheme 4

On 3.7L and 4.7L engines, the accessory drive belt tensioner is equipped with an indexing tang on back of tensioner and an indexing stop on tensioner housing. If a new accessory drive 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.

1. Remove accessory drive belt. Refer to «BELT, Serpentine , Removal»(ref-457792-S18686393612012030200000) . WARNING: Because of high spring pressure, do not attempt to disassemble automatic tensioner. Unit is serviced as an assembly.
2. Remove tensioner (3) assembly from timing chain cover.

The coolant recovery/overflow bottle (2) 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 recovery/overflow bottle (2) and returned to a proper level in the radiator.

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 require 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.

The Exhaust Gas Recirculation cooler is located above the exhaust manifold on the right side of the engine. Using engine coolant, the EGR cooler reduces the temperature of the exhaust gas that is recirculated to the air intake.

Exhaust gas enter the rear portion of the EGR Cooler from the exhaust manifold. The gas is cooled as it passes through the EGR Cooler and then enters the EGR crossover tube and is routed to the EGR valve.

Coolant enters the rear of the EGR Cooler and flow the same direction as the exhaust gases.

Scheme 5

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Scheme 9

Scheme 10

Scheme 11

Scheme 12

Scheme 13

Scheme 14

Scheme 15

1. Disconnect both negative battery cables.
2. Remove the bolts (1) and the engine cover.
3. Drain cooling system below level of EGR cooler. Refer to «Standard Procedure»(ref-457792-S30781673372012030200000) .
4. Remove the air cleaner assembly. Refer to «BODY, Air Cleaner , Removal , 3.7L»(ref-457795-S05169193642012030200000) «BODY, Air Cleaner , Removal , 4.7L»(ref-457796-S06661718552012030200000) «BODY, Air Cleaner , Removal , 5.7L»(ref-457797-S42752377112012030200000) «BODY, Air Cleaner , Removal , 6.7L»(ref-457798-S28601491212012030200000) .
5. Disconnect the breather hose (3).
6. Loosen the clamp (1) and remove the outlet tube (2) from the turbocharger. 1 - B + CONNECTOR 2 - GENERATOR 3 - FIELD WIRE CONNECTOR
7. Remove the generator. Refer to «GENERATOR , Removal»(ref-457799-S36013499732012030200000) .
8. Remove the EGR cooler bypass valve. Refer to «VALVE, Exhaust Gas Recirculation (EGR) Cooler Bypass , Removal»(ref-457800-S17754219502012030200000) .
9. Remove the clamp (2) securing the EGR cooler (1) to exhaust transfer manifold (3).
10. Remove the nuts (4) and the exhaust transfer manifold (3).
11. If equipped, remove the retaining nut and position aside the transmission fill tube from the EGR cooler.
12. As illustrated, using a suitable pair of channel lock pliers, remove forward coolant tube (2) from EGR cooler (1).
13. Disconnect breather hose (1), remove the bolt (3) and remove the breather tube (2).
14. Remove the bolt (2), and remove rear coolant tube from connection (1) and (4).
15. Remove EGR cooler mount bolts (3).
16. Remove EGR cooler flange nuts (1).
17. Remove EGR cooler and discard the flange gasket.
18. If damaged, remove EGR cooler mounting support.

Scheme 16

1. Remove EGR Cooler. Refer to «COOLER, EGR , Removal»(ref-457792-S12900673252012030200000) .
2. Spray the internal cavity of EGR Cooler (2) with hot tap water for 10 minutes.
3. Plug the EGR Cooler inlet (1) with a locally obtained rubber expansion plug to make a watertight seal.
4. Following instruction on the container, mix MOPAR® EGR System Cleaner and hot tap water with a ratio of one part EGR Cleaner, four parts water.
5. Position the EGR Cooler with the outlet (3) facing up. Fill EGR Cooler with hot tap water and MOPAR® EGR System Cleaner until cooler is completely full. Soak for one hour.
6. Remove the plug from EGR Cooler inlet (1). Drain cleaning solution from cooler. Discard according to local governmental regulations.
7. Rinse the EGR Cooler (2) using hot tap water until all cleaning solution has been rinsed clean. Dry completely.
8. Install EGR Cooler. Refer to «COOLER, EGR , Installation»(ref-457792-S13222462612012030200000) .

Scheme 17

Scheme 18

1. Install EGR cooler support bracket, if removed and tighten mounting bolts finger tight. If the EGR cooler support bracket was already installed, loosen the bolts to finger tight.
2. Using a new gasket, position EGR cooler (2) on exhaust manifold flange. Tighten flange nuts (1) to finger tight.
3. Using a new gasket, install the exhaust transfer manifold (3) Tighten nuts (4) to finger tight.
4. Using a new gasket, install the clamp (2) securing the EGR cooler (1) to exhaust transfer manifold (3), make sure that the bellows pilot is centered in the EGR cooler outlet. Tighten clamp finger tight. NOTE: Lubricate the new O-rings with a soapy water solution.
5. Install EGR Cooler mounting bolts (3) finger tight.
6. Using new O-rings, install the rear coolant tube to connection (4) then (1) and install the bolt (2) finger tight.
7. If equipped, position back the transmission fill tube (2) to the EGR cooler (1) finger tight.
8. Tighten nuts (1) on the EGR cooler inlet flange to the exhaust manifold to 60 N.m (44 ft. lbs.).
9. Using a crisscross pattern, tighten bolt (2) and (3) to 24 N.m 18 ft. lbs.) to secure the EGR cooler onto the EGR cooler mounting bracket.
10. Tighten the EGR cooler mounting bracket to cylinder head bolts to 36 N.m (27 ft. lbs.). NOTE: Lubricate the new O-rings with a soapy water solution.
11. Using a new O-ring (2), install the forward coolant tube (3) onto EGR cooler (1).
12. Tighten nuts (4) on the exhaust transfer manifold (3) to 43 N.m (18 ft. lbs.).
13. Tighten clamp (2) to 10 N.m (89 in. lbs.).
14. If equipped, tighten the nut (1) on the transmission fill tube (2) 10 N.m (89 in. lbs.).
15. Install the breather tube (2) and connect breather hose (1), Tighten the bolt (3) 24 N.m (18 ft. lbs.).
16. Install the EGR cooler bypass valve. Refer to «VALVE, Exhaust Gas Recirculation (EGR) Cooler Bypass , Installation»(ref-457800-S31040949252012030200000) . 1 - B + CONNECTOR 2 - GENERATOR 3 - FIELD WIRE CONNECTOR
17. Install the generator. Refer to «GENERATOR , Installation»(ref-457799-S02313752592012030200000) .
18. Install the outlet tube (2) to the turbocharger and tighten the clamp (1) 11 N.m (95 in. lbs.).
19. Connect the breather hose (3).
20. Install the air cleaner assembly. Refer to «BODY, Air Cleaner , Installation , 3.7L»(ref-457795-S37004940822012030200000) «BODY, Air Cleaner , Installation , 4.7L»(ref-457796-S16050623352012030200000) «BODY, Air Cleaner , Installation , 5.7L»(ref-457797-S01216084882012030200000) «BODY, Air Cleaner , Installation , 6.7L»(ref-457798-S12411770922012030200000) .
21. Install engine cover and tighten bolts (1) to 10 N.m (89 in. lbs.).
22. Connect negative battery cable(s).
23. Fill coolant system. Refer to «Standard Procedure»(ref-457792-S30781673372012030200000) .
24. Start engine and check for coolant or exhaust leaks.

Scheme 19

Scheme 20

1. Disconnect and isolate the negative battery cable.
2. Remove the upper radiator seal push pins (1).
3. Remove the upper radiator seal plastic rivets (2).
4. Remove the upper radiator seal.
5. If equipped, remove the viscous fan assembly from the water pump hub shaft. Refer to «FAN, Cooling, Electric , Removal»(ref-457792-S13033663812012030200000) or «FAN, Cooling, Viscous , Removal»(ref-457792-S41329399382012030200000) .
6. Disconnect the radiator fan (3) electrical connector.
7. Remove the fan shroud (1, 2) to radiator mounting bolts (4).
8. Disengage the fan shroud's (1, 2) lower retaining clips and position the fan shroud (1, 2) towards the rear of vehicle.
9. Disengage the electric cooling fan (3) to radiator upper retaining clips.
10. Disengage the electric fan (3) to radiator lower retaining clips.
11. Pulling upward remove the viscous fan, radiator fan shroud (1, 2) and the electric cooling fan (3) as an assembly.
12. The lower fan shroud (1) can be removed from the upper fan shroud (2) if needed.
13. If damaged, remove radiator fan resistor from shroud (1, 2).

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

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 CAN Bus 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. Cooling fan control
10. Temperature gauge operation
11. A/C cutoff at high coolant temperatures
12. EGR solenoid on/off times (if equipped)
13. Evaporation System Integrity Monitor (ESIM) operation (if equipped)
14. Radiator fan relay on/off times (if equipped)
15. Target idle speed

Scheme 21

1. Partially drain the cooling system.
2. Disconnect the electrical connector from the ECT sensor (3).
3. Remove the sensor from the intake manifold (4).

Scheme 22

1. Partially drain the cooling system. Refer to «Standard Procedure»(ref-457792-S30781673372012030200000) .
2. Disconnect the electrical connector from the ECT sensor (1).
3. Remove the sensor from the intake manifold (4).

Scheme 23

Note. Viscous fan, fan shroud and electric cooling fan removed for clarity.

1. Partially drain the cooling system. Refer to «Standard Procedure»(ref-457792-S30781673372012030200000) . WARNING: Hot, pressurized coolant can cause injury by scalding. Cooling system must be partially drained before removing the engine coolant temperature (ECT) sensor.
2. Disconnect the electrical connector from the engine coolant temperature (ECT) sensor (2).
3. Remove the engine coolant temperature (ECT) sensor (2) from the water pump assembly.

Scheme 24

1. Partially drain the cooling system. Refer to «Standard Procedure»(ref-457792-S30781673372012030200000) .
2. Remove the engine trim cover.
3. Remove the upper EGR tube (2). Refer to «TUBE, Exhaust Gas Recirculation (EGR), Crossover , Removal»(ref-457800-S05224501002012030200000) .
4. Remove heat shield.
5. Disconnect the electrical connector (2) from the ETC sensor (3).
6. Remove the ETC sensor from the cylinder head.

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.