Engine Cooling System: Diagnosis Dodge Pickup R2500

INSPECTION

1. Remove fan blade assembly from viscous fan drive unit (six bolts).
2. Lay fan on a flat surface with leading edge facing down. With tip of blade touching flat surface, replace fan if clearance between opposite blade and surface is greater than 2.0 mm (.090 inch). Rocking motion of opposite blades should not exceed 2.0 mm (.090 inch). Test all blades in this manner.
3. Inspect fan assembly for cracks, bends, or broken welds. Replace fan if any damage is found.

1. Remove fan blade assembly from viscous fan drive unit (six bolts).
2. Lay fan on a flat surface with leading edge facing down. With tip of blade touching flat surface, replace fan if clearance between opposite blade and surface is greater than 2.0 mm (.090 inch). Rocking motion of opposite blades should not exceed 2.0 mm (.090 inch). Test all blades in this manner.
3. Inspect fan assembly for cracks, bends, or broken welds. Replace fan if any damage is found.

DIAGNOSIS AND TESTING

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.

Scheme 57

1. Disconnect the battery negative cables.
2. Drain the coolant. Refer to «COOLING»(ref-189654-S13811322982005091200000).
3. Remove the power cord from the heater by unplugging (Scheme 57)
4. Loosen (but do not completely remove) the screw at center of block heater (Scheme 57)
5. Remove the block heater 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.

ON-BOARD DIAGNOSTICS

All gasoline powered models are equipped with On-Board Diagnostics for certain cooling system components. Refer to DIAGNOSIS AND TESTING - ON-BOARD DIAGNOSTICS (OBD) for additional information. If the Powertrain Control Module (PCM) detects low engine coolant temperature, it will record a Diagnostic Trouble Code (DTC) in the PCM memory. Do not change a thermostat for lack of heat as indicated by the instrument panel gauge or by poor heater performance unless a DTC is present. Refer to DIAGNOSIS AND TESTING for other probable causes.

The DTC can also be accessed through the DRBIII® scan tool. Refer to the appropriate SELF-DIAGNOSTICS article for diagnostic information and operation of the DRBIII® scan tool.

All gasoline powered models are equipped with On-Board Diagnostics for certain cooling system components. Refer to DIAGNOSIS AND TESTING - ON-BOARD DIAGNOSTICS (OBD) for additional information. If the powertrain control module (PCM) detects low engine coolant temperature, it will record a Diagnostic Trouble Code (DTC) in the PCM memory. Do not change a thermostat for lack of heat as indicated by the instrument panel gauge or by poor heater performance unless a DTC is present. Refer to DIAGNOSIS AND TESTING for other probable causes.

The DTC can also be accessed through the DRBIII® scan tool. Refer to the appropriate Self-Diagnostics section for diagnostic information and operation of the DRBIII® scan tool.

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 effect 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. Use the block heater if the outside temperature is below 4°C (40°F). Do not use the block heater if the outside temperature is above 4°C (40°F).

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.

1. To determine if the thermostat is defective, it must be removed from the vehicle. Refer to «REMOVAL»(ref-189656-S34594164282005091200000) .
2. 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. Refer to «COOLING»(ref-189654-S13811322982005091200000) .
3. Place the thermostat into a container filled with water.
4. Place the container on a hot plate or other suitable heating device.
5. Place a commercially available radiator thermometer into the water.
6. Apply heat to the water while observing the thermostat and thermometer.
7. 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.

All gasoline powered models are equipped with On-Board Diagnostics for certain cooling system components. Refer to SELF-DIAGNOSTICS - 3.7L, 5.9L (GASOLINE) & 8.0L for additional information. If the powertrain control module (PCM) detects low engine coolant temperature, it will record a Diagnostic Trouble Code (DTC) in the PCM memory. DO NOT change a thermostat for lack of heat as indicated by the instrument panel gauge or by poor heater performance unless a DTC is present. Refer to the Diagnosis section of this group for other probable causes. For other DTC numbers, (Refer to SELF-DIAGNOSTICS - 3.7L, 5.9L (GASOLINE) & 8.0L ).

The DTC can also be accessed through the DRB scan tool. Refer to the appropriate Powertrain Diagnostic Procedures information for diagnostic information and operation of the DRB scan tool.

Use the following procedure to determine if coolant is flowing through the cooling system.

1. Idle engine until operating temperature is reached. If the upper radiator hose is warm to the touch, the thermostat is opening and coolant is flowing to the radiator. WARNING: Hot, pressurized coolant can cause injury by scalding. Using a rag to cover the radiator pressure cap, open radiator cap slowly to the first stop. This will allow any built-up pressure to vent to the reserve/overflow tank. After pressure build-up has been released, remove cap from filler neck.
2. Drain a small amount of coolant from the radiator until the ends of the radiator tubes are visible through the filler neck. Idle the engine at normal operating temperature. If coolant is flowing past the exposed tubes, the coolant is circulating.

Inspect the radiator side tanks for cracks, broken or missing fittings. Also inspect the joint where the tanks seam up to the radiator core for signs of leakage and/or deteriorating seals.

Inspect radiator core for corroded, bent or missing cooling fins. Inspect the core for bent or damaged cooling tubes.

Use the following procedure to determine if coolant is flowing through the cooling system.

1. Idle engine until operating temperature is reached. If the upper radiator hose is warm to the touch, the thermostat is opening and coolant is flowing to the radiator. WARNING: Hot, pressurized coolant can cause injury by scalding. Using a rag to cover the radiator pressure cap, open radiator cap slowly to the first stop. This will allow any built-up pressure to vent to the reserve/overflow tank. After pressure build-up has been released, remove cap from filler neck.
2. Drain a small amount of coolant from the radiator until the ends of the radiator tubes are visible through the filler neck. Idle the engine at normal operating temperature. If coolant is flowing past the exposed tubes, the coolant is circulating.

Scheme 58

1. Disconnect both battery negative cables. WARNING: DO NOT remove the cylinder block drain plugs or loosen the radiator draincock with the system hot and under pressure. Serious burns from coolant can occur.
2. Drain the cooling system. Refer to «COOLING»(ref-189654-S13811322982005091200000). 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, such as Special Clamp Tool (Number 6094). Snap-On Clamp Tool (Number HPC-20) may be used for larger clamps. Always wear safety glasses when servicing constant tension clamps. CAUTION: A number or letter is stamped into the tongue of constant tension clamps. If replacement is necessary, use only an original equipment clamp with a matching number or letter
3. Remove air box and turbocharger inlet tube.
4. Remove coolant tank hose, washer bottle hose and the positive battery cable from the fastening clips located on top of the radiator.
5. Remove hose clamps and hoses from radiator.
6. Remove the power steering cooler mounting bolts, and position the power steering cooler out of the way.
7. Disconnect the transmission cooler lines at the transmission. The transmission cooler will remain on the radiator, and can be removed as an assembly.
8. Remove the lower shroud assembly and the electronic viscous fan wiring from the upper shroud assembly.
9. Remove the two radiator upper mounting bolts see scheme 46
10. Lift radiator straight up and out of engine compartment. The bottom of the radiator is equipped with two alignment dowels that fit into holes in the lower radiator support panel. Rubber biscuits (insulators) are installed to these dowels. Take care not to damage cooling fins or tubes on the radiator and air conditioning condenser when removing.

Inspect the radiator side tanks for cracks, broken or missing fittings also inspect the joint where the tanks seam up to the radiator core for signs of leakage and/or deteriorating seals.

Inspect radiator core for corroded, bent or missing cooling fins. Inspect the core for bent or damaged cooling tubes.

Hold cap at eye level, right side up. The vent valve see scheme 49 at bottom of cap should be 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.

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 59

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.

Visually inspect the water pump and replace if it has any of the following conditions

1. The body is cracked or damaged.
2. Water leaks from the shaft seal. This is evident by traces of coolant below the vent hole.
3. Loose or rough turning bearing.
4. Impeller rubbing the pump body.

Inspect the water pump assembly for cracks in the housing, water leaks from shaft seal, worn bearing or impeller rubbing either the pump body or timing chain case/cover.

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.

Visually inspect the water pump and replace if it has any of the following conditions

1. The body is cracked or damaged.
2. Water leaks from the shaft seal. This is evident by traces of coolant below the vent hole.
3. Loose or rough turning bearing.
4. Impeller rubbing the pump body.

Scheme 60

1. Install new O-ring seal in groove on water pump see scheme 61
2. Install water pump see scheme 60 Tighten mounting bolts to 24 N.m (18 ft. lbs.) torque.
3. Install accessory drive belt. Refer to «DRIVE BELTS - 5.9L DIESEL»(ref-189655-S26332597982005091200000).
4. Install the bolt retaining the wiring harness near top of water pump.
5. Fill cooling system. Refer to «COOLING»(ref-189654-S13811322982005091200000).
6. Connect both battery cables.
7. Start and warm the engine. Check for leaks.