Engine Cooling System: Other Dodge Pickup R2500

ETHYLENE-GLYCOL MIXTURES

The use of aluminum cylinder blocks, cylinder heads and water pumps requires special corrosion protection. Only Mopar® Antifreeze/Coolant, 5 year/100,000 Mile Formula (ethylene-glycol base coolant with corrosion inhibitors called HOAT, for Hybrid Organic Additive Technology) is recommended. This coolant offers the best engine cooling without corrosion when mixed with 50% distilled water to obtain a freeze point of -37°C (-35°F).

The required ethylene-glycol (antifreeze) and water mixture depends upon the climate and vehicle operating conditions. The antifreeze concentration must always be a minimum of 44 percent, year-round in all climates. If percentage is lower than 44 percent, engine parts may be eroded by cavitation, and cooling system components may be severely damaged by corrosion. Maximum protection against freezing is provided with a 68% antifreeze concentration, which prevents freezing down to -67.7° C (-90° F). A higher percentage will freeze at a warmer temperature. Also, a higher percentage of antifreeze can cause the engine to overheat, because the specific heat of antifreeze is lower than that of water.

Use of 100 percent ethylene-glycol will cause formation of additive deposits in the system, as the corrosion inhibitive additives in ethylene-glycol require the presence of water to dissolve. The deposits act as insulation, causing temperatures to rise to as high as 149° C (300° F). This temperature is hot enough to melt plastic and soften solder. The increased temperature can result in engine detonation. In addition, 100 percent ethylene-glycol freezes at 22° C (-8° F).

PROPYLENE-GLYCOL MIXTURES

Its overall effective temperature range is smaller than that of ethylene-glycol. The freeze point of 50/50 propylene-glycol and water is -32° C (-26° F). 5° C higher than ethylene-glycol's freeze point. The boiling point (protection against summer boil-over) of propylene-glycol is 125° C (257° F) at 96.5 kPa (14 psi), compared to 128° C (263° F) for ethylene-glycol. Use of propylene-glycol can result in boil-over or freeze-up on a cooling system designed for ethylene-glycol. Propylene glycol also has poorer heat transfer characteristics than ethylene-glycol. This can increase cylinder head temperatures under certain conditions.

Propylene-glycol/ethylene-glycol mixtures can cause the destabilization of various corrosion inhibitors, causing damage to the various cooling system components. Also, once ethylene-glycol and propylene-glycol based coolants are mixed in the vehicle, conventional methods of determining freeze point will not be accurate. Both the refractive index and specific gravity differ between ethylene-glycol and propylene-glycol.

HOAT COOLANT

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 PERFORMANCE

The required ethylene-glycol (antifreeze) and water mixture depends upon climate and vehicle operating conditions. The coolant performance of various mixtures follows

Pure Water - Water can absorb more heat than a mixture of water and ethylene-glycol. This is for purpose of heat transfer only. Water also freezes at a higher temperature and allows corrosion.

100 percent Ethylene-Glycol - The corrosion inhibiting additives in ethylene-glycol need the presence of water to dissolve. Without water, additives form deposits in system. These act as insulation, causing temperature to rise to as high as 149°C (300°F). This temperature is hot enough to melt plastic and soften solder. The increased temperature can result in engine detonation. In addition, 100 percent ethylene-glycol freezes at -22°C (-8°F).

50/50 Ethylene-Glycol and Water - Is the recommended mixture, it provides protection against freezing to -37°C (-34°F). The antifreeze concentration must always be a minimum of 44 percent, year-round in all climates. If percentage is lower, engine parts may be eroded by cavitation. Maximum protection against freezing is provided with a 68 percent antifreeze concentration, which prevents freezing down to -67.7°C (-90°F). A higher percentage will freeze at a warmer temperature. Also, a higher percentage of antifreeze can cause the engine to overheat because specific heat of antifreeze is lower than that of water.

COOLANT SELECTION AND ADDITIVES

The use of aluminum cylinder blocks, cylinder heads and water pumps requires special corrosion protection. Only Mopar® Antifreeze/Coolant, 5 Year/100,000 Mile Formula (glycol base coolant with corrosion inhibitors called HOAT, for Hybrid Organic Additive Technology) is recommended. This coolant offers the best engine cooling without corrosion when mixed with 50% distilled water to obtain 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.

CLEANING

Clean the fan blades using a mild soap and water. Do not use an abrasive to clean the blades.

Clean the fan blades using a mild soap and water. Do not use an abrasive to clean the blades.

3.7L V-6

The Engine Coolant Temperature (ECT) sensor on the 3.7L engine is installed into a water jacket at front of intake manifold, near rear of generator (Scheme 85)

1. Partially drain the cooling system. Refer to «COOLING»(ref-189654-S13811322982005091200000) .
2. Disconnect the electrical connector from the ECT sensor.
3. Remove the sensor from the intake manifold.

4.7L V-8

The Engine Coolant Temperature (ECT) sensor on the 4.7L V-8 engine is located near the front of the intake manifold (Scheme 86)

Scheme 85

1. Partially drain the cooling system. Refer to «COOLING»(ref-189654-S13811322982005091200000) .
2. Disconnect the electrical connector from the ECT sensor.
3. Remove the sensor from the intake manifold.

5.7L V-8

The Engine Coolant Temperature (ECT) sensor on the 5.7L engine is located under the air conditioning compressor (Scheme 87) It is installed into a water jacket at the front of the cylinder block (Scheme 88)

1. Partially drain the cooling system. Refer to «COOLING»(ref-189654-S13811322982005091200000).
2. Remove fan belt.
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.
4. Disconnect electrical connector from sensor (Scheme 88)
5. Remove sensor from cylinder block.

5.9L Diesel

The Engine Coolant Temperature (ECT) sensor on the 5.9L diesel engine is located near the thermostat housing see scheme 15

Scheme 86

1. Partially drain the cooling system. Refer to «COOLING»(ref-189654-S13811322982005091200000) .
2. Disconnect the electrical connector from the sensor.
3. Remove the sensor from the cylinder head.

5.9L V-8 Gas

Scheme 87

1. Partially drain the cooling system. Refer to «COOLING»(ref-189654-S13811322982005091200000).
2. Disconnect the electrical connector from the sensor see scheme 16
3. Engines with air conditioning: When removing the connector from the sensor, do not pull directly on the wiring harness. The connector is snapped onto the sensor. It is not equipped with a lock type tab.
4. Remove the sensor from the intake manifold.

8.0L V-10

The Engine Coolant Temperature (ECT) sensor on the 8.0L V-10 engine is threaded into the thermostat housing see scheme 17

Scheme 88

1. Partially drain the cooling system. Refer to «COOLING»(ref-189654-S13811322982005091200000) .
2. Disconnect the electrical connector from the sensor.
3. Remove the sensor from the cylinder head.

1. Apply thread sealant to sensor threads.
2. Install sensor to engine.
3. Tighten sensor to 11 N.m (8 ft. lbs.) torque.
4. Connect electrical connector to sensor.
5. Replace any lost engine coolant. Refer to «COOLING»(ref-189654-S13811322982005091200000) .

1. Apply thread sealant to sensor threads.
2. Install sensor to engine.
3. Tighten sensor to 11 N.m (8 ft. lbs.) torque.
4. Connect electrical connector to sensor.
5. Replace any lost engine coolant. Refer to «COOLING»(ref-189654-S13811322982005091200000) .

1. Apply thread sealant to sensor threads.
2. Install sensor to engine.
3. Tighten sensor to 11 N.m (8 ft. lbs.) torque.
4. Connect electrical connector to sensor.
5. Replace any lost engine coolant. Refer to «COOLING»(ref-189654-S13811322982005091200000) .

1. Apply thread sealant to sensor threads.
2. Install sensor to engine.
3. Tighten sensor to 18 N.m (13 ft. lbs.) torque.
4. Connect electrical connector to sensor.
5. Replace any lost engine coolant. Refer to «COOLING»(ref-189654-S13811322982005091200000) .

1. Apply thread sealant to sensor threads.
2. Install sensor to engine.
3. Tighten sensor to 6-8 N.m (55-75 in. lbs.) torque.
4. Connect electrical connector to sensor. The sensor connector is symmetrical (not indexed). It can be connected to sensor in either direction.
5. Refill cooling system. Refer to «COOLING»(ref-189654-S13811322982005091200000) .

1. Apply thread sealant to sensor threads.
2. Install sensor to engine.
3. Tighten sensor to 11 N.m (8 ft. lbs.) torque.
4. Connect electrical connector to sensor.
5. Replace any lost engine coolant. Refer to «COOLING»(ref-189654-S13811322982005091200000) .

LEAKS

Viscous fan drive operation is not affected by small oil stains near the drive bearing. If leakage appears excessive, replace the fan drive unit.

VISCOUS DRIVE

If the fan assembly free-wheels without drag (the fan blades will revolve more than five turns when spun by hand), replace the fan drive. This spin test must be performed when the engine is cool.

For the following test, the cooling system must be in good condition. It also will ensure against excessively high coolant temperature.

1. Drill a 3.18-mm (1/8-in) diameter hole in the top center of the fan shroud.
2. Obtain a dial thermometer with an 8-inch stem (or equivalent). It should have a range of -18°-to-105°C (0°-to-220° F). Insert thermometer through the hole in the shroud. Be sure that there is adequate clearance from the fan blades.
3. Connect a tachometer and an engine ignition timing light. The timing light is to be used as a strobe light. This step cannot be used on the diesel engine.
4. Block the air flow through the radiator. Secure a sheet of plastic in front of the radiator. Use tape at the top to secure the plastic, and be sure that the air flow is blocked.
5. Be sure that the air conditioner (if equipped) is turned off. WARNING: Use extreme caution when the engine is operating. DO NOT stand in a direct line with the fan. DO NOT put your hands near the pulleys, belts or fan. DO NOT wear loose clothing.
6. Start the engine and operate at 2400 RPM. Within ten minutes, the air temperature (indicated on the dial thermometer) should be up to 88° C (190° F). Fan drive engagement should start to occur at/between: 3.7L Automatic - 93° C - 99°C (200° F - 210° F) 3.7L Manual/4.7L Automatic/5.9L - 85° to 91° C (185° to 195° F) 4.7L Manual - 74° to 79° C (165° to 175° F) Engagement is distinguishable by a definite increase in fan flow noise (roaring). The timing light also will indicate an increase in the speed of the fan.
7. When viscous drive engagement is verified, remove the plastic sheet. Fan drive disengagement should start to occur at or between: 3.7L Automatic - 76°C to 81°C (168° F to 178° F) 3.7L Manual/4.7L Automatic/ 5.9L - 67°C to 73°C (153° F to 163° F) 4.7L Manual - 56°C to 62°ohmsC (133° F to 143° F) 8.0L engine - 88° to 96° C (190° to 205° F) A definite decrease of fan flow noise (roaring) should be noticed. If not, replace the defective viscous fan drive unit.

Viscous fan drive operation is not affected by small oil stains near the drive bearing. If leakage appears excessive, replace the fan drive unit.

ELECTRONICALLY CONTROLLED VISCOUS DRIVE

If the fan assembly free-wheels without drag (the fan blades will revolve more than five turns when spun by hand), replace the fan drive. This spin test must be performed when the engine is cool.

For the following test, the cooling system must be in good condition. It also will ensure against excessively high coolant temperature.

The Electronic Viscous Fan drive can be tested using the DRB III scan tool.

1. Set the parking brake, and verify the transmission is in Park or Neutral.
2. Start and allow engine to reach normal operating temperatures.
3. With engine idling, connect the DRB III and select appropriate model year and engine option.
4. Locate and select actuator tests, then select PWM Viscous Fan.
5. Monitor fan speed and duty cycle; verify that the fan speed increments are proportional to the duty cycle percentage during the actuation event.

Clean radiator fins are necessary for good heat transfer. The radiator and oil cooler fins should be cleaned when an accumulation of debris has occurred. With the engine cold, apply cold water and compressed air to the back (engine side) of the radiator to flush the radiator and/or oil coolers of debris.

Clean radiator fins are necessary for good heat transfer. The radiator and oil cooler fins should be cleaned when an accumulation of debris has occurred. With the engine cold, apply cold water and compressed air to the back (engine side) of the radiator to flush the radiator and/or oil coolers of debris.

RADIATOR CAP-TO-FILLER NECK SEAL

The pressure cap upper gasket (seal) pressure relief can be tested by removing overflow hose from the radiator filler neck tube. Attach the hose of the pressure tester tool 7700 (or equivalent) to the tube. It will be necessary to disconnect hose from its adapter for the filler neck. Pump air into radiator. The pressure cap upper gasket should relieve at 69 to 124kPa (10 to 18 psi) and hold pressure at a minimum of 55 kPa (8 psi).

Do not remove the radiator cap at any time except for the following purposes

1. Check and adjust antifreeze freeze point.
2. Refill the system with new antifreeze.
3. Conducting service procedures.
4. Checking for vacuum leaks.

RADIATOR CAP

Remove the cap from the radiator. Be sure that the sealing surfaces are clean. Moisten the rubber gasket with water, and install the cap on the pressure tester 7700 or an equivalent see scheme 48

Operate the tester pump to bring the pressure to 104 kPa (15 psi) on the gauge. If the pressure cap fails to hold pressure of at least 97 kPa (14 psi), replace the cap. Refer to the following CAUTION.

The pressure cap may test properly while positioned on tool 7700 (or equivalent). It may not hold pressure or vacuum when installed on the radiator. If so, inspect the radiator filler neck and radiator cap's top gasket for damage. Also inspect for dirt or distortion that may prevent the cap from sealing properly.

Scheme 89

Use only a mild soap and water to clean the radiator cap. Using any type of solvent may cause damage to the seal in the radiator cap.

Clean gasket mating surfaces as necessary.

Clean the gasket mating surface. Use caution not to damage the gasket sealing surface.

Clean gasket mating surfaces as necessary.

WATER PUMP BYPASS HOSE WITH AIR CONDITIONING

If equipped with A/C, the generator and A/C compressor along with their common mounting bracket see scheme 62 must be partially removed. Removing the generator or A/C compressor from their mounting bracket is not necessary. Also, discharging the A/C system is not necessary. Do not remove any refrigerant lines from A/C compressor.

Scheme 90

Scheme 91

Scheme 92

Scheme 93

1. Disconnect the negative battery cable.
2. Partially drain the cooling system. Refer to «COOLING»(ref-189654-S13811322982005091200000). Do not waste reusable coolant. If the solution is clean, drain the coolant into a clean container for reuse.
3. Remove the upper radiator hose clamp at the radiator. A special clamp tool must be used to remove the constant tension clamps. Remove the hose at the radiator.
4. Unplug the wiring harness from the A/C compressor.
5. Remove the air cleaner assembly.
6. Remove the accessory drive belt. Refer to «DRIVE BELTS - 5.9L»(ref-189655-S27970610772005091200000).
7. The drive belt idler pulley must be removed to gain access to one of the A/C compressor/generator bracket mounting bolts. Remove the idler pulley bolt and remove idler pulley see scheme 63
8. Remove the engine oil dipstick tube mounting bolt at the side of the A/C-generator mounting bracket.
9. Disconnect the throttle body control cables.
10. Remove the heater hose coolant return tube mounting bolt ( see scheme 64, see scheme 65 ) and remove the tube from the engine. Discard the old tube O-ring.
11. Remove the bracket-to-intake manifold bolts (number 1 and 2 see scheme 62 ).
12. Remove the remaining bracket-to-engine bolts see scheme 65
13. Lift and position the generator and A/C compressor (along with their common mounting bracket) to gain access to the bypass hose. A block of wood may be used to hold the assembly in position.
14. Loosen and position both hose clamps to the center of the bypass hose. A special clamp tool must be used to remove the constant tension clamps. Remove the hose from the vehicle.

WATER PUMP BYPASS HOSE WITHOUT AIR CONDITIONING

A water pump bypass hose see scheme 66 is used between the intake manifold and water pump on all gas powered engines. To test for leaks, refer to DIAGNOSIS AND TESTING.

Scheme 94

1. Partially drain the cooling system. Refer to «COOLING»(ref-189654-S13811322982005091200000) . Do not waste reusable coolant. If the solution is clean, drain the coolant into a clean container for reuse. WARNING: Constant tension hose clamps are used on most cooling system hoses. When removing or installing, use only tools designed for servicing this type of clamp. Always wear safety glasses when servicing constant tension clamps. CAUTION: A number or letter is stamped into the tongue of the constant tension clamps. If replacement is necessary, use only an original equipment clamp with a matching number or letter and width
2. Loosen both of the bypass hose clamps and position them to the center of the hose.
3. Remove the hose from the vehicle.

Scheme 95

1. Position the bypass hose clamps to the center of the bypass hose.
2. Install the bypass hose to the engine.
3. Secure both of the hose clamps.
4. Install the generator-A/C mounting bracket assembly to the engine. Tighten bolt number 1 see scheme 63 to 41 N.m (30 ft. lbs.). Tighten bolt number 2 see scheme 63 to 28 N.m (20 ft. lbs.). Tighten bracket mounting bolts see scheme 63 to 40 N.m (30 ft. lbs.).
5. Install a new O-ring to the heater hose coolant return tube. Coat the new O-ring with antifreeze before installation.
6. Install the coolant return tube and its mounting bolt to the engine.
7. Connect the throttle body control cables.
8. Install the oil dipstick mounting bolt.
9. Install the idler pulley. Tighten the bolt to 41 N.m (30 ft. lbs.) see scheme 67
10. Install the drive belt. Refer to «DRIVE BELTS - 5.9L»(ref-189655-S27970610772005091200000). CAUTION: When installing the serpentine accessory drive belt, the belt must be routed correctly. If not, the engine may overheat due to the water pump rotating in the wrong direction. Refer to «DRIVE BELTS - 5.9L»(ref-189655-S27970610772005091200000). The correct belt with the correct length must be used.
11. Install the air cleaner assembly.
12. Install the upper radiator hose to the radiator.
13. Connect the throttle cable to the clip at the radiator fan shroud.
14. Connect the wiring harness to the A/C compressor.
15. Fill the cooling system. Refer to «COOLING»(ref-189654-S13811322982005091200000).
16. Start and warm the engine. Check for leaks.

1. Position the bypass hose clamps to the center of the bypass hose.
2. Install the bypass hose to the engine.
3. Secure both of the hose clamps.
4. Fill the cooling system. Refer to «COOLING»(ref-189654-S13811322982005091200000) .
5. Start and warm the engine. Check for leaks.