PRESSURE TESTER METHOD
The engine should be at normal operating temperature. Recheck the system cold if the cause of coolant loss is not located during the warm engine examination.
| WARNING | Hot, pressurized coolant can cause injury by scalding. |
Carefully remove the radiator pressure cap from the filler neck and check the coolant level. Push down on the cap to disengage it from the stop tabs. Wipe the inside of the filler neck and examine the lower inside sealing seat for nicks, cracks, paint, dirt and solder residue. Inspect the radiator-to- reserve/overflow tank hose for internal obstructions. Insert a wire through the hose to be sure it is not obstructed.
Inspect the cams on the outside of the filler neck. If the cams are damaged, seating of the pressure cap valve and tester seal will be affected.
Attach pressure tester (7700 or an equivalent) to radiator filler neck.
Operate the tester pump to apply 103.4 kPa (15 psi) pressure to the system. If the hoses enlarge excessively or bulges while testing, replace as necessary. Observe the gauge pointer and determine the condition of the cooling system according to following criteria
Holds Steady: If the pointer remains steady for two minutes, serious coolant leaks are not present in system. However, there could be an internal leak that does not appear with normal system test pressure. If it is certain that coolant is being lost and leaks cannot be detected, inspect for interior leakage or perform Internal Leakage Test. Refer to INTERNAL LEAKAGE INSPECTION .
Drops Slowly: Indicates a small leak or seepage is occurring. Examine all of the connections for seepage or slight leakage with a flashlight. Inspect the radiator, hoses, gasket edges and heater. Seal the small leak holes with a Sealer Lubricant (or equivalent). Repair the leak holes and inspect the system again with pressure applied.
Drops Quickly: Indicates that serious leakage is occurring. Examine the system for external leakage. Block side panels are embossed to highlight core plugs. Remove embossed noise panels to inspect and or repair core plugs. If leaks are not visible, inspect for internal leakage.
TRAILER TOWING
Consult Trailer Towing section of owners manual. Do not exceed limits.
RECENT SERVICE OR ACCIDENT REPAIR
Determine if any recent service has been performed on vehicle that may affect the cooling system. This may be
- Engine adjustments (incorrect timing)
- Slipping engine accessory drive belt(s)
- Brakes (possibly dragging)
- Changed parts. Incorrect water pump or pump rotating in wrong direction due to belt not correctly routed
- Reconditioned radiator or cooling system refilling (possibly under filled or air trapped in system).
- Service to electrically controlled viscous fan clutch
Note. If investigation reveals none of the previous items as a cause for an engine overheating complaint, refer to COOLING SYSTEM DIAGNOSIS CHART .
These charts are to be used as a quick-reference only.
| CONDITION | POSSIBLE CAUSES | CORRECTION |
|---|---|---|
| TEMPERATURE GAUGE READS LOW | 1. Vehicle is equipped with a heavy duty cooling system. | 1. None. System operating normally. |
| NOTE: Information on dash cluster is displayed based on broadcast data from ECM. DTC will be set for engine sensor circuit concern. | 2. Thermostat stuck open | 2. Inspect and test thermostat. |
| 3. Coolant level low. | 3. Fill cooling system. See STANDARD PROCEDURE . | |
| 4. Temperature gauge not functioning correctly. | 4. Check cluster. Refer to DIAGNOSIS AND TESTING . | |
| 5. Engine sensor stuck in range | 5. Monitor sensor with scan tool to verify sensor reading changes with increasing temperature. | |
| 6. Engine sensor failed out of range. | 6. A DTC will be set. | |
| 7. Electronically Controlled Viscous Fan Drive/mechanical viscous fan not operating properly. | 7. Check Electronically Controlled Viscous Fan Drive. See DIAGNOSIS AND TESTING . | |
| TEMPERATURE GAUGE READS HIGH. COOLANT MAY OR MAY NOT BE LEAKING FROM SYSTEM | 1. Vehicle overloaded, high ambient (outside) temperatures with A/C turned on, stop and go driving or prolonged operation at idle speeds. | 1. Temporary condition, repair not required. Notify customer of vehicle operation instructions located in Owners Manual. |
| NOTE: Information on dash cluster is displayed based on broadcast information from ECM. DTC will be set for engine sensor circuit concern. | 2. Temperature gauge not functioning correctly. | 2. Check cluster. Refer to DIAGNOSIS AND TESTING . |
| 3. Air trapped in cooling system | 3. Drain cooling system, and refill. See STANDARD PROCEDURE . | |
| 4. Radiator cap faulty. | 4. Replace radiator cap. | |
| 5. Plugged A/C or radiator cooling fins. | 5. Clean all debris away from A/C and radiator cooling fins. | |
| 6. Coolant mixture incorrect. | 6. Drain cooling system and refill with correct mixture. See STANDARD PROCEDURE . | |
| 7. Thermostat stuck shut. | 7. Inspect and test thermostat. Replace thermostat if necessary. | |
| 8. Bug screen or winter front being used. | 8. Remove bug screen or winter front. | |
| 9. Electronically controlled viscous fan drive not operating properly. | 9. Check viscous fan. See DIAGNOSIS AND TESTING . | |
| 10. EGR Cooler leaking internally | 10. Replace EGR Cooler. See REMOVAL . | |
| 11. EGR cooler leaking exhaust pressure to cooling system. | 11. Replace EGR Cooler. See REMOVAL . | |
| 10. Cylinder head gasket leaking. | 10. Check for leaking head gaskets. See DIAGNOSIS AND TESTING . | |
| 11. Heater core leaking. | 11. Replace heater core. | |
| 12. Cooling system hoses leaking. | 12. Tighten clamps or Replace hoses. | |
| 13. Brakes dragging. | 13. Check brakes. Refer to DIAGNOSIS AND TESTING . | |
| 14. Accessory drive belt. | 14. Inspect. Replace as necessary. | |
| 15. Water Pump. | 15. Inspect and replace as necessary. | |
| 16. Engine sensor stuck in range. | 16. Monitor sensor with scan tool to verify sensor reading changes increase in temperature. | |
| 17. Temperature sensor failed out of range. | 17. A DTC will be set. | |
| TEMPERATURE GAUGE READING INCONSISTENT (ERRATIC, CYCLES OR FLUCTUATES) | 1. Heavy duty cooling system, extreme cold ambient (outside) temperature or heater blower motor in high position. | 1. None. System operating normally. |
| NOTE: Information on dash cluster is displayed based on broadcast data from ECM. DTC will be set for engine sensor circuit wiring. | 2. Temperature gauge or sensor defective. | 2. Check cluster or engine coolant temp sensor. Refer to DIAGNOSIS AND TESTING . |
| 3. Temporary heavy usage or load. | 3. None. Normal condition. | |
| 4. Air trapped in cooling system. | 4. Fill cooling system. See STANDARD PROCEDURE . | |
| 5. Water pump. | 5. Replace water pump. | |
| 6. Air leak on suction side of water pump. | 6. Check for leak. See DIAGNOSIS AND TESTING . | |
| RADIATOR CAP LEAKING STEAM AND OR COOLANT INTO RESERVOIR BOTTLE. (TEMPERATURE GAUGE MAY READ HIGH) | 1. Radiator cap defective. | 1. Replace radiator cap. |
| 2. Radiator neck surface damaged. | 2. Replace radiator. | |
| HOSE OR HOSES COLLAPSE WHEN ENGINE IS COOLING. | 1. Vacuum created in cooling system on engine cool-down is not being relieved through coolant reservoir/overflow system. | 1. Replace radiator cap, check vent hose between radiator and reservoir bottle for blockage also check reservoir bottle vent for blockage. |
| NOISY FAN | 1. Fan blade(s) loose, damaged. | 1. Replace fan blade assembly. |
| 2. Electronically controlled viscous fan drive/mechanical viscous fan. | 2. None. Normal condition. | |
| 3. Fan blades striking surrounding objects. | 3. Locate contact point and repair as necessary. | |
| 4. Electronically controlled viscous fan drive/mechanical viscous fan bearing concern. | 4. Check viscous fan drive. See DIAGNOSIS AND TESTING . | |
| 5. Electronically controlled viscous fan/mechanical viscous fan stuck on. | 5. Check viscous fan drive. See DIAGNOSIS AND TESTING . | |
| 6. Obstructed air flow through radiator. | 6. Remove obstruction. | |
| INADEQUATE AIR CONDITIONER PERFORMANCE (COOLING SYSTEM SUSPECTED) | 1. Radiator and/or A/C condenser air flow obstructed. | 1. Remove obstruction and/or clean. |
| 2. Electronically controlled viscous fan drive/mechanical viscous fan not working. | 2. Check viscous fan drive. See DIAGNOSIS AND TESTING . | |
| 3. Air seals around radiator damaged or missing. | 3. Inspect air seals, repair or replace as necessary. | |
| INADEQUATE HEATER PERFORMANCE. GAUGE MAY OR MAY NOT READ LOW. | 1. Heavy duty cooling system, and cooler ambient temperatures. | 1. None. Normal condition. |
| 2. Obstruction in heater hoses. | 2. Remove hoses, remove obstruction. | |
| 3. Electronically controlled viscous fan/mechanical viscous fan stuck on. | Check viscous fan drive. See DIAGNOSIS AND TESTING . | |
| 4. Water pump damaged. | 4. Replace water pump. | |
| HEAT ODOR | 1. Damaged or missing drive line heat shields. | 1. Repair or replace damaged or missing heat shields. |
| 2. Electronically controlled viscous fan drive//mechanical viscous fan damaged. | 2. Check viscous fan drive. See DIAGNOSIS AND TESTING . |
COOLING SYSTEM DIAGNOSIS CHART
ADDING ADDITIONAL COOLANT
The use of aluminum cylinder blocks, cylinder heads and water pumps requires special corrosion protection. In order to maintain the required protection for these components and cooling system performance, only use the appropriate fluid. Refer to DESCRIPTION when servicing the vehicle.
| CAUTION | Do not use coolant additives that are claimed to improve engine cooling. |
Do not remove the radiator cap to add antifreeze mixture to the system. When adding antifreeze mixture to maintain the correct level, do so only at the reserve/overflow bottle. Remove the radiator cap only for testing or when refilling the system after service. Removing the cap unnecessarily can cause loss of antifreeze mixture and allow air to enter the system, which produces corrosion.
| WARNING | Do not remove or loosen the radiator cap with the cooling system hot and under pressure. Serious burns from the coolant or high pressure steam can occur. |
CLEANING
Drain the cooling system and refill with water. Run the engine with the radiator cap installed until the upper radiator hose is hot. Stop the engine and drain the water from system. If the water is dirty, fill the system with water, run the engine and drain the system. Repeat this procedure until the water drains clean.
CHEMICAL CLEANING
In some instances, use a radiator cleaner (Mopar® Radiator Kleen or equivalent) before flushing. This will soften scale and other deposits and aid flushing operation.
| CAUTION | Follow manufacturers instructions when using these products. |
COOLING-FILLING-DIESEL
Clean cooling system prior to refilling. See STANDARD PROCEDURE .
- Close radiator drain plug. CAUTION: All air must be purged from the 6.7L engine when refilling the cooling system. Failure to do so can cause EGR Cooler cracking which can lead to catastrophic engine and exhaust system damage.
- 6.7L Only. Remove vent fitting. NOTE: The diesel engine is equipped with two one-way check valves (jiggle pins). The check valves are used as a servicing feature and will vent air when the system is being filled. Water pressure (or flow) will hold the valves closed.
- Using Tool 8195, fill the cooling system with coolant mixture. See «DESCRIPTION»(ref-303804-S32321397352008103100000) . On 6.7L ONLY, fill system until coolant comes out of vent hole.
- Install vent fitting. Tighten to 6 N.m (55 in. lbs.).
- Using Tool 8195, fill coolant recovery container to the FULL mark.
- Start and operate engine until thermostat opens. Upper radiator hose should be warm to touch.
- Accelerate engine from idle to 2500 RPM five times. (throttle snaps)
- Idle engine. Check coolant level in coolant recovery container. Fill to FULL line.
- Repeat step 7 .
- Shut off engine. Fill coolant recovery container to FULL line.
- Remove Tool 8195. Install radiator cap.
COOLING-FILLING-GAS ENGINES
The use of aluminum cylinder blocks, cylinder heads and water pumps requires special corrosion protection. In order to maintain the required protection for these components and cooling system performance, only use the appropriate fluid. Refer to DESCRIPTION when servicing the vehicle. 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). If it loses color or becomes contaminated, drain, flush, and replace with fresh properly mixed coolant solution.
Clean cooling system prior to refilling. See STANDARD PROCEDURE .
- Install cylinder block drain plugs. Coat the threads with Mopar® Thread Sealant with Teflon.
- Close radiator petcock.
- Fill cooling system with coolant. Refer to «DESCRIPTION»(ref-303775-S36523433622008103100000) .
- Fill coolant reserve/overflow tank to MAX mark on bottle.
- Start and operate engine until thermostat opens (upper radiator hose warm to touch).
- If necessary, add coolant to the coolant recovery container. This is done to maintain coolant level between the MAX and MIN marks. The level in the coolant recovery container may drop below the MIN mark after three or four warm-up and cool-down cycles.
COOLING-FILL VOLUMES
| DESCRIPTION | SPECIFICATION | |
|---|---|---|
| Metric | US | |
| 3.7L Engine | 16L | 17 qts |
| 4.7L Engine | 16L | 17 qts. |
| 5.7L Engine | 17.7L | 18.7 qts. |
| 5.9L Diesel Engine | 26.5L | 28.22 qts. |
| 6.7L Diesel Engine | 21.4L | 22.6 qts. |
Clean all foreign debris from belt pulley grooves. The belt pulleys must be free of oil, grease, and coolants before installing the drive belt.
COOLANT PERFORMANCE
The required ethylene-glycol 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. The increased temperature can result in severe engine damage. 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.
| CAUTION | Richer antifreeze mixtures cannot be measured with normal field equipment and can cause problems associated with 100 percent ethylene-glycol. |
ENGINE BLOCK HEATER
| 1 - ENGINE BLOCK HEATER |
If the unit does not operate, possible causes can be either the power cord or the heater element. Test the power cord for continuity with a 110-volt voltmeter or 110-volt test light. Test heater element continuity with an ohmmeter or a 12-volt test light.
| CAUTION | To prevent damage, the power cord must be secured in it's retainer clips and away from any components that may cause abrasion or damage, such as linkages, exhaust components, etc. |
Scheme 64
- Disconnect the battery negative cable.
- Drain the coolant. See «STANDARD PROCEDURE»(ref-303804-S21721751352008103100000) .
- Remove the power cord from the heater by unplugging.
- Loosen (but do not completely remove) the screw at center of block heater.
- Remove the block heater (1) by carefully prying from side-to-side. Note the direction of the heating element coil (up or down). The element coil must be installed correctly to prevent damage.
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.
Scheme 65
If the fan assembly does not free-wheel and a metallic grinding sound exists, replace the electronically controlled fan drive. See REMOVAL .
Note. The following test may take up to 15 minutes to perform.
The engine should be at normal operating temperature.
- Set the parking brake and verify the transmission is in park or neutral.
- Set air conditioner (if equipped) and blower fan to OFF.
- Start and allow engine to reach normal operating temperatures.
- Stop engine, connect the scan tool and select appropriate model year and engine option.
- Check for and correct existing DTC's
- Using Tool 6801, backprobe pin 1 of the electronically controlled viscous fan drive connector, with the harness connected located at the lower fan shroud to battery ground. NOTE: The fan drive control coil is energized to 12 volts at this time. WARNING: A spark may occur when connecting pin to ground. Be sure that no combustible material is in the area.
- Using the scan tool, verify that DTC 0480 set. If it is not set, verify that a good ground is available.
- Start the engine.
- Actuate engine speed to 2000 RPM.
- Go to the SENSOR screen and observe the fan speed.
- Run the engine at 2000 RPM until the fan speed increases to 1850 RPM or more for 30 seconds. NOTE: Fan RPM may ramp up slowly. NOTE: It maybe take 15 minutes before fan speed increases.
- The fan speed should be in accordance to the chart below.
- If fan speed does not increase, make sure that the jumper wire has a good connection. If so replace the electronically control viscous fan drive.
- If the fan speed does increase and there is still a concern, refer to the appropriate Engine ELECTRICAL DIAGNOSTICS article to diagnosis the electronically controlled viscous fan drive control circuit.
| ELECTRONICALLY CONTROLLED VISCOUS FAN DRIVE SPEEDS | |
|---|---|
| ENGINE RPM | FAN RPM (Min) |
| 1000 | 950 |
| 1500 | 1420 |
| 2000 | 1850 |
| 2500 | 2230 |
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
For the following test, the cooling system must be in good condition. It also will ensure against excessively high coolant temperature.
| WARNING | Be sure that there is adequate fan blade clearance before drilling. |
- Drill a 3.18-mm (1/8-in) diameter hole in the top center of the fan shroud.
- 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.
- 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.
- 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.
- Be sure that the air conditioner (if equipped) and blower fan 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.
- 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 - 85° - 91° C (185° - 195° F) 4.7L Manual - 74° - 79° C (165° - 175° F) 5.7L Automatic Standard Cool - 94° C - 99°C (201° F - 211° F) 5.7L Manual - 93° C - 100°C (199° F - 212° F) 5.7L Heavy Duty Snowplow - 76° C - 83°C (169° F - 181° 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.
- 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 - 81°C (168° F - 178° F) 3.7L Manual/4.7L Auto/5.9L - 67°C - 73°C (153° F - 163° F) 4.7L Manual - 56°C - 62°C (133° F - 143° F) 5.7L Automatic Standard Cool - 69° C - 74°C (156° F - 166° F) 5.7L Manual - 71° C - 76°C (160° F - 170° F) 5.7L Heavy Duty Snowplow - 55° C - 60°C (168° F - 178° F) A definite decrease of fan flow noise (roaring) should be noticed. If not, replace the defective viscous fan drive unit.
| CAUTION | Some engines equipped with serpentine drive belts have reverse rotating fans and viscous fan drives. Installation of the wrong fan or viscous fan drive can result in engine overheating. |
| CAUTION | If the viscous fan drive is replaced because of mechanical damage, the cooling fan blades should also be inspected. Inspect for fatigue cracks, loose blades, or loose rivets that could have resulted from excessive vibration. Replace fan blade assembly if any of these conditions are found. Also inspect water pump bearing and shaft assembly for any related damage due to a viscous fan drive malfunction. |
Scheme 66
| 1 - SPECIAL TOOL 6958 SPANNER WRENCH WITH ADAPTER PINS 8346 |
|---|
| 2 - FAN |
- Do Not attempt to remove the fan/viscous fan drive assembly from the vehicle at this time. CAUTION: If the viscous fan drive is replaced because of mechanical damage, the cooling fan blades should also be inspected. Inspect for fatigue cracks, loose blades, or loose rivets that could have resulted from excessive vibration. Replace fan blade assembly if any of these conditions are found. Also inspect water pump bearing and shaft assembly for any related damage due to a viscous fan drive malfunction.
- Disconnect negative battery cable from battery.
- Remove coolant reserve/overflow container from fan shroud and lay aside. Do Not disconnect the hoses or drain coolant from the container.
- The thermal viscous fan drive/fan blade assembly is attached (threaded) to the water pump hub shaft. see scheme 60 Remove the fan blade/viscous fan drive assembly from the water pump by turning the mounting nut counterclockwise as viewed from the front. Threads on the viscous fan drive are RIGHT-HAND. A 36 MM Fan Wrench should be used to prevent pulley from rotating. (Scheme 66)
- Do Not unbolt the fan blade assembly from viscous fan drive at this time. see scheme 60
- Remove the fan shroud-to-radiator mounting bolts.
- Pull the lower shroud mounts out of the radiator tank clips.
- Remove the fan shroud and fan blade/viscous fan drive assembly as a complete unit from vehicle. 1 - WATER PUMP BYPASS HOSE 2 - FAN BLADE ASSEMBLY 3 - VISCOUS FAN DRIVE 4 - WATER PUMP AND PULLEY 5 - Bolts (4)
- After removing the fan blade/viscous fan drive assembly, do not place the viscous fan drive in a horizontal position. If stored horizontally, silicone fluid in the viscous fan drive could drain into its bearing assembly and contaminate lubricant. CAUTION: Do not remove water pump pulley-to-water pump bolts. This pulley is under spring tension.
- Remove four bolts securing fan blade assembly to viscous fan drive. see scheme 60
| CAUTION | Some engines equipped with serpentine drive belts have reverse rotating fans and viscous fan drives. They are marked with the word REVERSE to designate their usage. Installation of the wrong fan or viscous fan drive can result in engine overheating. |
Scheme 67
| 1 - NUTS |
|---|
| 2 - ENGINE MOUNTED FAN SHROUD |
| CAUTION | If the electronically controlled viscous fan drive is replaced because of mechanical damage, the cooling fan blades should also be inspected. Inspect for fatigue cracks, or chipped blades that could have resulted from excessive vibration. Replace fan blade assembly if any of these conditions are found. Also inspect wiring harness and connectors for damage. |
Scheme 68
- Disconnect the battery negative cables.
- Remove fan shroud-to-engine bracket nuts (1). 1 - WIRING BRACKET 2 - WIRING BRACKET MOUNTING BOLT 3 - SHROUD MOUNTING BRACKET 4 - ELECTRONICALLY CONTROLLED VISCOUS FAN CONNECTOR
- Disconnect electronically controlled viscous fan electrical connector (4) at lower fan shroud bracket.
- Remove wiring bracket -to-lower fan shroud bracket mounting bolt (2).
- Remove fan drive wire harness support from fan shroud. CAUTION: Do not remove the fan pulley bolts. This pulley is under spring tension.
- The electronically controlled viscous fan drive/fan blade assembly is attached (threaded) to the fan pulley shaft. Remove the fan blade/fan drive assembly from fan pulley by turning the mounting nut counterclockwise (as viewed from front). Threads on the viscous fan drive are RIGHT-HAND. A 36 MM Fan Wrench can be used. Place a bar or screwdriver between the fan pulley bolts to prevent pulley from rotating. NOTE: It may be necessary to loosen the top two fan shroud brackets. Removal of the engine mounted fan shroud brackets is not necessary unless removing or installing the engine.
- Collapse fan shroud toward front of vehicle and remove fan drive/fan blade and fan shroud as an assembly. 1 - ELECTRICAL CONNECTOR 2 - VISCOUS FAN DRIVE 3 - FAN BLADE 4 - BOLT (6) 5 - RADIATOR FAN PULLEY CAUTION: The electronically controlled viscous fan drive is vibration and impact sensitive, especially at the electrical connectors. Do not drop the unit.
- Remove the six fan blade-to-viscous fan drive mounting bolts.
- Inspect the fan for cracked, chipped or damaged fan blades.
Clean the fan blades using a mild soap and water. Do not use an abrasive to clean the blades.
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.
DIESEL ENGINE
The cooling system used with the diesel engine provides the extra coolant capacity and extra cooling protection needed for higher GVWR (Gross Vehicle Weight Rating) and GCWR (Gross Combined Weight Rating) vehicles.
This system capacity will not affect warm up or cold weather operating characteristics if the thermostat is operating properly. This is because coolant will be held in the engine until it reaches the thermostat "set" temperature.
Diesel engines, due to their inherent efficiency are slower to warm up than gasoline powered engines, and will operate at lower temperatures when the vehicle is unloaded. Because of this, lower temperature gauge readings for diesel versus gasoline engines may, at times be normal.
Typically, complaints of low engine coolant temperature are observed as low heater output when combined with cool or cold outside temperatures.
To help promote faster engine warm-up, the electric engine block heater must be used with cool or cold outside temperatures. This will help keep the engine coolant warm when the vehicle is parked.
A "Cold Weather Cover" is available from the parts department through the Mopar Accessories product line. This accessory cover is designed to block airflow entering the radiator and engine compartment to promote faster engine warm-up. It attaches to the front of the vehicle at the grill opening. The cover is to be used with cool or cold temperatures only. If used with high outside temperatures, serious engine damage could result. Refer to the literature supplied with the cover for additional information.
For engines equipped with exhaust brakes, this device can be used to aid engine warm-up while the engine is idling.
- To determine if the thermostat is defective, it must be removed from the vehicle. See «REMOVAL»(ref-303804-S00373739022008103100000) .
- After the thermostat has been removed, examine the thermostat and inside of thermostat housing for contaminants. If contaminants are found, the thermostat may already be in a "stuck open" position. Flush the cooling system before replacing thermostat. See «STANDARD PROCEDURE»(ref-303804-S21721751352008103100000) .
- Place the thermostat into a container filled with water.
- Place the container on a hot plate or other suitable heating device.
- Place a commercially available radiator thermometer into the water.
- Apply heat to the water while observing the thermostat and thermometer.
- The thermostat will begin to open at 85.5 - 89.4°C. (186 - 193°F). If the valve starts to move before this temperature is reached, it is opening too early. Replace thermostat. The thermostat should be fully open (valve will stop moving) at 97°C (207°F). If the valve is still moving when the water temperature reaches 97°C (207°F), it is opening too late. Replace thermostat. If the valve refuses to move at any time, replace thermostat.
The cooling system used with the diesel engine provides the extra coolant capacity and extra cooling protection needed for higher GVWR (Gross Vehicle Weight Rating) and GCWR (Gross Combined Weight Rating) vehicles.
This system capacity will not affect warm up or cold weather operating characteristics if the thermostat is operating properly. This is because coolant will be held in the engine until it reaches the thermostat "set" temperature.
Diesel engines, due to their inherent efficiency are slower to warm up than gasoline powered engines, and will operate at lower temperatures when the vehicle is unloaded. Because of this, lower temperature gauge readings for diesel versus gasoline engines may, at times be normal.
Typically, complaints of low engine coolant temperature are observed as low heater output when combined with cool or cold outside temperatures.
To help promote faster engine warm-up, the electric engine block heater must be used with cool or cold outside temperatures. This will help keep the engine coolant warm when the vehicle is parked.
A "Cold Weather Cover" is available from the parts department through the Mopar Accessories product line. This accessory cover is designed to block airflow entering the radiator and engine compartment to promote faster engine warm-up. It attaches to the front of the vehicle at the grill opening. The cover is to be used with cool or cold temperatures only. If used with high outside temperatures, serious engine damage could result. Refer to the literature supplied with the cover for additional information.
For engines equipped with exhaust brakes, this device can be used to aid engine warm-up while the engine is idling.
- To determine if the thermostat is defective, it must be removed from the vehicle. See «REMOVAL»(ref-303804-S00373739022008103100000) .
- After the thermostat has been removed, examine the thermostat and inside of thermostat housing for contaminants. If contaminants are found, the thermostat may already be in a "stuck open" position. Flush the cooling system before replacing thermostat. See «STANDARD PROCEDURE»(ref-303804-S21721751352008103100000) .
- Place the thermostat into a container filled with water.
- Place the container on a hot plate or other suitable heating device.
- Place a commercially available radiator thermometer into the water.
- Apply heat to the water while observing the thermostat and thermometer.
- The thermostat will begin to open at 85.5 - 89.4°C. (186 - 193°F). If the valve starts to move before this temperature is reached, it is opening too early. Replace thermostat. The thermostat should be fully open (valve will stop moving) at 97°C (207°F). If the valve is still moving when the water temperature reaches 97°C (207°F), it is opening too late. Replace thermostat. If the valve refuses to move at any time, replace thermostat.
Scheme 69
| 1 - THERMOSTAT HOUSING |
|---|
| 2 - THERMOSTAT LOCATION |
| 3 - THERMOSTAT AND GASKET |
| 4 - TIMING CHAIN COVER |
| WARNING | Do not loosen the radiator draincock with the cooling system hot and pressurized. Serious burns from the coolant can occur. |
- Disconnect the negative battery cable.
- Drain the cooling system. See «STANDARD PROCEDURE»(ref-303804-S21721751352008103100000).
- Raise and support the vehicle.
- Remove the splash shield.
- Remove the lower radiator hose clamp and the lower radiator hose at the thermostat housing.
- Remove the thermostat housing mounting bolts, thermostat housing and thermostat. (Scheme 69)
Scheme 70
| 1 - BOLT |
|---|
| 2 - THERMOSTAT HOUSING |
| 3 - CLAMP |
| 4 - RADIATOR HOSE |
| WARNING | Do not loosen the radiator draincock with the cooling system hot and pressurized. Serious burns from the coolant can occur. |
- Disconnect the negative battery cable.
- Drain the cooling system
- Remove the radiator hose clamp (3) and radiator hose (4) at the thermostat housing (2).
- Remove the thermostat housing mounting bolts (1), thermostat housing (2) and thermostat.
RADIATOR CAP-TO-FILLER NECK
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 124 kPa (10 to 18 psi) and hold pressure at a minimum of 55 kPa (8 psi).
| WARNING | The warning words, "DO NOT OPEN HOT", on radiator pressure cap, are a safety precaution. When hot, pressure builds up in cooling system. To prevent scalding or injury, radiator cap should not be removed while system is hot and/or under pressure. |
Do not remove the radiator cap at any time except for the following purposes
- Check and adjust antifreeze freeze point.
- Refill the system with new antifreeze.
- Conducting service procedures.
- Checking for vacuum leaks.
| WARNING | If vehicle has been run recently, wait at least 15 minutes before removing radiator cap. With a rag, squeeze radiator upper hose to check if system is under pressure. Place a rag over cap and without pushing cap down, rotate it counterclockwise to first stop. Allow fluid to escape through the coolant reserve/overflow hose into reserve/overflow tank. Squeeze radiator upper hose to determine when pressure has been released. When coolant and steam stop being pushed into tank and system pressure drops, remove radiator cap completely. |
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.
Scheme 71
| 1 - STAINLESS-STEEL SWIVEL TOP |
|---|
| 2 - RUBBER SEALS |
| 3 - VENT VALVE |
| 4 - RADIATOR TANK |
| 5 - FILLER NECK |
| 6 - OVERFLOW NIPPLE |
| 7 - MAIN SPRING |
| 8 - GASKET RETAINER |
Hold cap at eye level, right side up. The vent valve at bottom of cap should closed. A slight downward pull on the vent valve should open it. If the rubber gasket has swollen and prevents vent valve from opening, replace cap. (Scheme 71)
Hold cap at eye level, upside down. If any light can be seen between vent valve and rubber gasket, replace cap. A replacement cap must be the type designed for a coolant reserve/overflow system with a completely sealed diaphragm spring and a rubber gasket. This gasket is used to seal to radiator filler neck top surface. Use of proper cap will allow coolant return to radiator.
Scheme 72
| 1 - INTEGRAL WATER PUMP PULLEY |
|---|
| 2 - TIMING CHAIN COVER |
| 3 - THERMOSTAT HOUSING |
| 4 - HEATER HOSE FITTINGS |
| 5 - WATER PUMP |
A centrifugal water pump circulates coolant through the water jackets, passages, intake manifold, radiator core, cooling system hoses and heater core. The pump is driven from the engine crankshaft by a single serpentine drive belt.
The water pump impeller is pressed onto the rear of a shaft that rotates in bearings pressed into the housing. The housing has two small holes to allow seepage to escape. The water pump seals are lubricated by the antifreeze in the coolant mixture. No additional lubrication is necessary.
WATER PUMP
A quick test to determine if pump is working is to check if heater warms properly. A defective water pump will not be able to circulate heated coolant through the long heater hose to the heater core.
Clean the gasket mating surface. Use caution not to damage the gasket sealing surface.