Engine Cooling System: Diagnosis Dodge Avenger II рестайлинг

COOLING SYSTEM RELATED DIAGNOSTICS

The Engine Control Module (ECM) has been programmed to monitor certain cooling system components

1. If the engine has remained cool for too long a period, such as with a stuck open thermostat, a Diagnostic Trouble Code (DTC) can be set.
2. Coolant temperature sensor circuit problems can set a DTC.
3. If the problem is sensed in a monitored circuit often enough to indicated an actual problem, a DTC is stored. The DTC will be stored in the ECM memory for eventual display to the service technician.

ACCESSING DIAGNOSTIC TROUBLE CODES

To read DTC's and to obtain cooling system data, refer to EMISSIONS CONTROL .

ERASING TROUBLE CODES

After the problem has been repaired, use the scan tool to erase a DTC. Refer to POWERTRAIN CONTROL MODULE (PCM) - ELECTRICAL DIAGNOSTICS - 40TE AUTOMATIC TRANSMISSION or POWERTRAIN CONTROL MODULE (PCM) - ELECTRICAL DIAGNOSTICS - 62TE AUTOMATIC TRANSMISSION Diagnostic Procedures service information for operation of the scan tool.

Establish what driving conditions caused the complaint. Abnormal loads on the cooling system such as the following may be the cause

1. PROLONGED IDLE
2. VERY HIGH AMBIENT TEMPERATURE
3. SLIGHT TAIL WIND AT IDLE
4. SLOW TRAFFIC
5. TRAFFIC JAMS
6. HIGH SPEED OR STEEP GRADES

Driving techniques that avoid overheating are

1. Idle with A/C off when temperature gauge is at end of normal range.
2. Increasing engine speed up to 2000 RPM with transmission in park or neutral for more airflow is recommended.

INTERNAL LEAKAGE INSPECTION

Remove engine oil pan drain plug and drain a small amount of engine oil. If coolant is present in the pan, it will drain first because it is heavier than oil. An alternative method is to operate engine for a short period to churn the oil. After this is done, remove engine dipstick and inspect for water globules. Also inspect transmission dipstick for water globules and transmission fluid cooler for leakage.

Operate engine without pressure cap on radiator until thermostat opens. Attach a Pressure Tester to filler neck. If pressure builds up quickly it indicates a combustion leak exists. This is usually the result of a cylinder head gasket leak or crack in engine. Repair as necessary.

If there is not an immediate pressure increase, pump the Pressure Tester. Do this until indicated pressure is within system range of 110 kPa (16 psi). Fluctuation of gauge pointer indicates compression or combustion leakage into cooling system.

Because the vehicle is equipped with a catalytic converter, do not remove spark plug cables or short out cylinders to isolate compression leak.

If the needle on dial of pressure tester does not fluctuate, race engine a few times to check for an abnormal amount of coolant or steam. This would be emitting from exhaust pipe. Coolant or steam from exhaust pipe may indicate a faulty cylinder head gasket, cracked engine cylinder block or cylinder head.

A convenient check for exhaust gas leakage into cooling system is provided by a commercially available Block Leak Check tool. Follow manufacturers instructions when using this product.

INSPECTION

After performing a cleaning/flush procedure, inspect all hoses, clamps and connections for deterioration and leaks. Inspect radiator and heater core for leaks.

PRESSURE RELIEF TESTING

The pressure cap upper gasket to filler neck seal can be checked by removing the overflow hose at the filler neck overflow nipple. Attach the radiator pressure tester to the filler neck overflow nipple, and pump air into the system. The pressure cap upper gasket should relieve pressure at 69-124 kPa (10-18 psi), and hold pressure at 55 kPa (8 psi) minimum.

There is no need to remove the pressure cap at any time except for the following purposes

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

Scheme 8

Hold the cap in your hand, right side up The vent valve at the bottom of the cap should fall open. Turn the cap upside down. The vent valve should close.

Replace the cap for any of the following conditions

1. Rubber gasket has swollen, preventing the valve from opening
2. Any light can be seen between the vent valve and the rubber gasket (with cap upside down)
3. Gasket on the bottom of the cap shows noticeable thinning
4. Cap has been through more than one engine overheat.

DIAGNOSIS AND TESTING - COOLANT CONCENTRATION TESTING

Coolant concentration should be checked when any additional coolant was added to system or after a coolant drain, flush and refill. The coolant mixture offers optimum engine cooling and protection against corrosion when mixed to a freeze point of -37°C (-34°F) to -46°C (-50°F). The use of a hydrometer or Tool (special tool #8266B, End Play Socket Set), refractometer can be used to test coolant concentration.

A hydrometer will test the amount of glycol in a mixture by measuring the specific gravity of the mixture. The higher the concentration of ethylene glycol, the larger the number of balls that will float, and higher the freeze protection (up to a maximum of 60% by volume glycol).

A Refractometer Tool (special tool #8286, Refractometer) will test the amount of glycol in a coolant mixture by measuring the amount a beam of light bends as it passes through the fluid.

Some coolant manufactures use other types of glycols into their coolant formulations. Propylene glycol is the most common new coolant. However, propylene glycol based coolants do not provide the same freezing protection and corrosion protection and are not recommended.

Scheme 9

Note. It is not necessary to remove draincock during a routine coolant drain.

1. Drain the cooling system. Refer to «STANDARD PROCEDURE»(ref-485484-S02211614932012071300000) .
2. Open the draincock by turning it counterclockwise until it stops.
3. Turn the draincock back (clockwise) 1/8 turn.
4. Pull the draincock from the radiator tank.

RADIATOR FAN TEST

Refer to the appropriate Diagnostic Information for testing the fan motor with the scan tool.

For wiring diagrams of the fan motor systems refer to appropriate Wiring Diagrams.

Scheme 10

1. Disconnect negative cable from auxiliary terminal.
2. Disconnect radiator fan electrical connector.
3. Remove the screws that secure the wiring harness loom to the upper radiator core support.
4. Partially drain cooling system. Refer to «STANDARD PROCEDURE»(ref-485484-S02211614932012071300000) .
5. Remove upper radiator hose at radiator.
6. Remove the oil indicator tube to help aid in the fan assembly removal.
7. Remove fasteners and upper clip attaching fan assembly to radiator.
8. Remove radiator fan assembly by lifting upward.

Inspect fan blades for damage. If the fan blades are warped, cracked, or otherwise damaged, it must be replaced with only the recommended replacement part for adequate strength, performance and safety.

Check fan motor operation. If fan motor is inoperative, and the fan blades are not damaged, the fan motor can be replaced separately.

DIAGNOSIS AND TESTING - ENGINE BLOCK HEATER TESTING

If unit does not operate, test power cord for continuity with a 110-volt voltmeter or 110-volt test light. Test heater element continuity with an ohmmeter or 12-volt test light.

Scheme 11

1. Drain cooling system. Refer to «STANDARD PROCEDURE»(ref-485484-S02211614932012071300000) .
2. Raise vehicle on hoist.
3. Detach power cord plug from block heater.
4. Loosen screw in center of heater. Remove block heater assembly.

Scheme 12

Scheme 13

1. Remove the A/C compressor (1) and position aside. Refer to «COMPRESSOR, A/C, REMOVAL»(ref-485480-S16902540862012071300000) . The heater block is located on the driver side towards the front of the engine.
2. Partially drain coolant from radiator and cylinder block. Refer to «STANDARD PROCEDURE»(ref-485484-S02211614932012071300000) .
3. Disconnect the power cord plug from block heater.
4. Loosen screw (2) from the heater. Remove block heater assembly (1).

DIAGNOSIS AND TESTING - WATER PUMP FLOW

To determine whether coolant is flowing through the cooling system, use one of the following procedures

Replace the water pump body assembly if it has any of these defects

1. Cracks or damage on the body.
2. Coolant leaks from the shaft seal, evident by wet coolant traces on the pump body.
3. Loose or rough turning bearing.
4. Impeller rubs either the pump body or the engine block.
5. Impeller loose or damaged.
6. Sprocket or sprocket flange either loose or damaged.

Inspect the radiator 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.

DIAGNOSIS AND TESTING - ENGINE COOLANT THERMOSTAT TESTING

The thermostat is operated by a wax filled container (pellet) which is sealed. When heated coolant reaches a predetermined temperature the wax pellet expands enough to overcome the closing spring and water pump pressure, which forces the valve to open. Coolant leakage into the pellet will cause a thermostat to fail open. Do not attempt to free up a thermostat with a screwdriver.

The thermostat that opens too soon type failure mode is included in the on-board diagnosis. The check engine light will be lit by an open too soon condition. If it has failed open, a Diagnostic Trouble Code (DTC) will be set. Do not change a thermostat for lack of heater performance or temperature gauge position, unless a DTC is present. For other probable causes. Refer to DIAGNOSIS AND TESTING . Thermostat failing shut is the normal long term mode of failure, and normally, only on high mileage vehicles. The temperature gauge will indicate this.

Scheme 14

1. Partially drain cooling system. Refer to «STANDARD PROCEDURE»(ref-485484-S02211614932012071300000) .
2. Remove air filter housing.
3. Disconnect coolant hose (1) from inlet housing (2).
4. Remove inlet housing bolts (3).
5. Remove thermostat assembly, and clean sealing surfaces.

Scheme 15

1. Partially drain cooling system. Refer to «STANDARD PROCEDURE»(ref-485484-S02211614932012071300000) .
2. Remove air filter housing.
3. Disconnect coolant hoses (1) from rear of coolant adapter (2).
4. Remove radiator hose (3).
5. Remove radiator hose (4) from front of coolant adapter (2).
6. Remove coolant adapter mounting bolts.
7. Carefully slide coolant adapter off water pump inlet tube and remove coolant adapter (2) and secondary thermostat.