| Diagnosis and Testing Special Tool(s) | | Cooling System Pressure Tester 303-396 (24-001-A) | | | Adaptor for Cooling System Pressure Tester 303-396-01 (24-001-01A) | | | Adaptor for Cooling System Pressure Tester 303-396-02 (24-001-02) | General Equipment Worldwide Diagnostic System (WDS) Inspection and Verification - Verify the customer concern by operating the system.
- Visually inspect for obvious signs of mechanical or electrical damage.
Visual Inspection Chart | Mechanical | Electrical | - Leaks
- Coolant expansion tank cap and seal
- Coolant expansion tank
- Radiator
- Water pump
- Accessory drive belt
| - Fuse(s)
- Wiring harness
- Loose or corroded connector(s)
- Cooling fan motor(s)
- Cylinder head temperature (CHT) sensor
- Powertrain control module (PCM)
| - If an obvious cause for an observed or reported concern is found, correct the cause (if possible) before proceeding to the next step.
- If the cause is not visually evident, verify the symptom and refer to the Symptom Chart.
Symptom Chart Symptom Chart | Symptom | Possible Sources | Action | | Loss of coolant | * Hose(s). * Hose connections. * Radiator. * Water pump. * Coolant expansion tank. * Heater core. * Gasket(s). * Engine casting cracks. * Engine block core plugs. | * CARRY OUT the Pressure Test Component Test in this section. | | The engine overheats | * Loss of coolant. | * REFER to Loss of Coolant in the Symptom Chart above. | | * System restriction. | * INSPECT the cooling system for blockages, air locks or restrictions. REPAIR as necessary. | | * Blocked radiator grille. | * INSPECT the radiator grille for obstructions and REMOVE as necessary. | | * Thermostat. | * CARRY OUT the Thermostat Test Component Test in this section. | | * Fuse(s). * Circuit(s). * Cooling fan motor. * CHT. * PCM. | * REFER to WDS | | * Water pump. | * CARRY OUT the Pressure Test Component Test in this section. INSPECT the water pump for leaks. INSTALL a new water pump or water pump gasket as necessary.
REFER to: Water Pump - 1.6L Zetec-SE (Sigma)/1.4L (303-03 Engine Cooling, Removal and Installation) /
Water Pump - 1.6L Zetec-E (Zetec)/1.8L Zetec-E (Zetec)/2.0L Zetec-E (Zetec) (303-03 Engine Cooling, Removal and Installation) /
Water Pump Housing - 1.6L Zetec-E (Zetec)/1.8L Zetec-E (Zetec)/2.0L Zetec-E (Zetec) (303-03 Engine Cooling, Removal and Installation) /
Water Pump - 1.8L Diesel (303-03 Engine Cooling, Removal and Installation).
| | * Accessory drive belt. | * CHECK the accessory drive belt for correct operation.
REFER to: Accessory Drive (303-05 Accessory Drive, Diagnosis and Testing).
| | * Towing weight exceeded. | * ADVISE the customer about the effects of exceeding the vehicle towing weight. | | The engine does not reach normal operating temperature | * Thermostat. | * CARRY OUT the Thermostat Test Component Test in this section. | | * Cooling fan motor. | * REFER to WDS. | | * Coolant expansion tank cap. | * CARRY OUT the Coolant Expansion Tank Cap Test Component Test in this section. | Component Tests Pressure Test - Open the hood and install protective fender covers.
WARNING:Never remove the coolant expansion tank cap under any circumstances while the engine is operating. Failure to follow these instructions may result in damage to the cooling system or engine and may cause personal injury. To avoid having scalding hot water or steam blow out of the cooling system, use extreme care when removing the coolant expansion tank cap from a hot cooling system. Wait until the engine has cooled, then wrap a thick cloth around the coolant expansion tank cap and turn it slowly until the pressure begins to release, step back while the pressure is released from the cooling system. When certain all the pressure has been released (still with a cloth) turn and remove the coolant expansion tank cap. Failure to follow these instructions may result in personal injury. - Carefully remove the coolant expansion tank cap from the coolant expansion tank to release pressure in the cooling system. Add coolant to the coolant expansion tank as necessary.
- Install the cooling system pressure tester to the coolant expansion tank and pressurize the cooling system to the coolant expansion tank cap lower limit.
- Observe the gauge reading for approximately two minutes. Pressure should not drop during this time.
- If the system holds pressure, proceed to Step 8.
- If the pressure drops, check for leaks at the engine to heater core hoses, engine to radiator hoses, bypass hose, water valve hose (if applicable), thermostat housing gasket, radiator and heater core, etc. Also refer to engine system checks if a leak cannot be located in the cooling system. Correct any leaks found and recheck the system.
- Release the cooling system pressure by turning the pressure relief screw on the cooling system pressure tester. Remove the cooling system pressure tester from the coolant expansion tank. Check the coolant level. Add coolant to the coolant expansion tank as necessary.
- Carry out the Cap Component Test in this section.
Radiator Leak Test, Removed From the Vehicle CAUTION:Do not leak test an aluminum radiator in the same water that is used to leak test copper/brass radiators. Flux and caustic cleaners may be present in the test water which will corrode aluminum. Clean the radiator before leak testing to prevent contamination of the test tank. Leak test the radiator in clean water with 138 kPa (20 psi) air pressure. A separate clean test tank is recommended for aluminum radiators. If a separate tank is not available for aluminum radiator testing, rinse the test tank each time before testing an aluminum radiator. Check it thoroughly for air leaks. INSTALL a new radiator if necessary.
REFER to: Radiator - Vehicles Built Up To: 09/2002 1.6L Zetec-SE (Sigma)/1.4L, Vehicles With: Manual Transaxle/4-Speed Automatic Transmission (4F27E) (303-03 Engine Cooling, Removal and Installation) /
Radiator - Vehicles Built From: 10/2002 1.6L Zetec-SE (Sigma), Vehicles With: Manual Transaxle (303-03 Engine Cooling, Removal and Installation) /
Radiator - 1.6L Zetec-E (Zetec)/1.8L Zetec-E (Zetec)/2.0L Zetec-E (Zetec) (303-03 Engine Cooling, Removal and Installation) /
Radiator - 2.0L Duratec-ST (Zetec) (303-03 Engine Cooling, Removal and Installation).
Coolant Expansion Tank Cap Pressure Test WARNING:Never remove the coolant expansion tank cap under any circumstances while the engine is operating. Failure to follow these instructions may result in damage to the cooling system or engine and may cause personal injury. To avoid having scalding hot water or steam blow out of the cooling system, use extreme care when removing the coolant expansion tank cap from a hot cooling system. Wait until the engine has cooled, then wrap a thick cloth around the coolant expansion tank cap and turn it slowly until the pressure begins to release, step back while the pressure is released from the cooling system. When certain all the pressure has been released (still with a cloth) turn and remove the coolant expansion tank cap. Failure to follow these instructions may result in personal injury. - Carefully remove the coolant expansion tank cap from the coolant expansion tank to release pressure in the cooling system. Add coolant to the coolant expansion tank as necessary.
- Use water to clean the area of the rubber seal and pressure relief valve. Install the cooling system pressure tester and adapter and immerse the coolant expansion tank pressure cap in water.
NOTE:If the plunger of the pump is depressed too quickly, an erroneous pressure reading will result. - Slowly depress the plunger of the pressure test pump until the pressure gauge reading stops increasing, and note highest pressure reading obtained.
- Release the cooling system pressure by turning the pressure release screw on the cooling system pressure tester. Tighten the pressure release screw and repeat step 3 at least twice to make sure the pressure test reading is repeatable and within acceptable gauge reading limits of the coolant expansion tank cap.
- If the pressure test gauge readings are not within acceptable gauge reading limits, INSTALL a new coolant expansion tank cap.
Thermostat, Electrical WARNING:Always vent the exhaust to the outside when carrying out this test. Failure to the follow this instruction may result in personal injury. NOTE:The following test should be carried out if the WDS is not available. NOTE:This procedure is most accurate if carried out indoors at less than 37.8°C (100°F) ambient air. This test may be carried out with or without the hood open and with the engine warm or cold. - Check the coolant level in the radiator and the coolant expansion tank. Fill as required.
- With the engine OFF, disconnect the cylinder head temperature (CHT) sensor electrical connector and attach Service Coolant Temperature Monitor Harness as a jumper between the PCM and the CHT. Attach a digital multimeter to the thermostat monitor harness. Voltage values (0 to 5 V) may now be monitored while the sensor retains its connection to the harness.
NOTE:Running this test with the vehicle in gear or with the A/C compressor clutch engaged (running) will cause incorrect diagnosis. - Place transmission in Park (P) or Neutral (N).
- Start the engine and allow to idle throughout this test. Allow the engine to run for 2 minutes, then record the CHT voltage. Record the CHT voltage every 60 seconds. When the CHT voltage trend changes direction or only changes slightly (0.03 volts or less) from the previous reading, record this as the thermostat opening voltage. Use the voltage and corresponding coolant temperature chart listed below.
| Coolant Temperature °C (°F) | CHT (volts) | | 20 (68) | 3.09 | | 40 (104) | 2.15 | | 70 (158) | 1.04 | | 80 (176) | 0.79 | | 90 (194) | 0.61 | | 97 (206) | 3.51 | | 105 (221) | 3.25 | - If the thermostat opening voltage is greater than 0.79 volts and less than 80°C (176°F), INSTALL a new thermostat.
- If the thermostat opening voltage is less than 0.79 volts and greater than 80°C (176°F), the thermostat is OK and should not be changed. Refer to the Symptom Chart for further instructions.
Thermostat Test - Using the WDS datalogger function, SELECT the following sensors (as applicable to the application):
- IAT - intake air temperature (IAT) sensor
- ECT - engine coolant temperature (ECT) sensor
- CHT - cylinder head temperature (CHT) sensor
- LOAD - engine load
- VSS - vehicle speed sensor (VSS)
- RPM - engine speed
- DSRPM - desired engine speed
The IAT sensor output is useful if the engine being tested is cold or after an over-night cold soak. The ECT sensor or CHT sensor and the IAT sensor should either indicate the same value or be within 1 to 2 degrees Celsius of each other. The ECT sensor output is important to display as it indicates the engine warm-up and opening temperature for the thermostat. It will initially indicate a slightly higher reading just before the thermostat opens and then drops back before settling to a near flat line output (see graphic below). B - Thermostat settles into a cyclic open and closure pattern CAUTION:If the ECT sensor output reaches the 120ºC default line under normal cooling system pressure, internal damage may be caused to the engine and a diagnostic trouble code (DTC) will be set in the PCM. The test should be stopped and the cause located and corrected. If the cooling system does not pressurize, the coolant will boil at 100ºC which may also damage the engine. CARRY OUT the Coolant Expansion Tank Cap Pressure Test Component Test in this section. If the WDS only allows the ECT sensor to be displayed in volts, refer to the following table for corresponding Celsius values: | Volts | ºCelsius | | 1.33 | 60 | | 1.02 | 70 | | 0.78 | 80 | | 0.60 | 90 | | 0.46 | 100 | | 0.35 | 110 | | 0.27 | 120 | The CHT sensor output is useful to examine the cylinder head temperature rise during the warm-up cycle and later during the normal light throttle cruise test. This sensor output may vary between vehicles with manual transmission and vehicles with automatic transmission and should be used for reference only. The LOAD display is used for reference as it is necessary to maintain a stable load line during the test. It is necessary to carry out the test under normal light throttle cruise driving conditions and average loads, typically 40% to 70% of the load value. The VSS output is used for reference but can help to identify misfires and sensors which fail during the warm-up cycle. The RPM display indicates the engine speed and can be compared with the DSRPM. The DSRPM is the desired or calculated idle speed which the PCM commands the engine to reach. If the thermostat opens too early (before the correct opening temperature has been reached), the engine will not reach this value. When using the WDS in data logger mode, the signals recorded should remain within the DEFAULT values set by the WDS. -
WARNING:Make sure that the WDS is placed in the vehicle so that it does not interfere with the safe operation of the vehicle. Do not place the WDS in the deployment path of any air bag. Failure to follow these instructions may result in personal injury. NOTE:The road test is best carried out with the aid of another technician in the vehicle to enable the vehicle to be driven safely while the sensor outputs are monitored within datalogger. If there is only one technician available, the WDS can be set up (using the record/capture mode camera icon) before leaving the workshop to record a 16 km (10 mile) test. NOTE:The results from the test are more conclusive if the engine is cold when the test is started. Carry out a road test. - Drive the vehicle at a constant throttle opening and set speed until the ECT value settles into a shallow rise and fall signal, close to a straight line. This indicates that the thermostat is functioning correctly.
NOTE:Some thermostats indicate the temperature(s) in Celsius and Fahrenheit. The graphic below shows the location and an example of the opening temperature (88ºC) and fully open temperature (102ºC) of a thermostat. The graphic below shows an alternative method used to show the opening temperature (88ºC) and fully open temperature (112ºC) of a thermostat. NOTE:Generally, most thermostats maintain a coolant temperature between 88ºC (190ºF) and 92ºC (198ºF) although dual stage electric thermostats may increase the coolant temperature up to 100ºC (212ºF) under light engine load conditions. The engine should start cleanly and the ECT value will rise quite quickly with smooth progression. If the ECT signal appears unstable or erratic, the ECT sensor, electrical connector and wiring harness to the PCM need to be visually inspected for damage, chafing or water ingress. The temperature should rise to approximately 90ºC for a thermostat that has an 88ºC value. The signal value will then fall as cooler coolant enters the engine. If the ECT value fails to maintain a constant value and falls back to lower figures, typically between 60ºC (140ºF) and 70ºC (150ºF), the thermostat and its sealing function within the thermostat housing must be checked. - INSTALL a new thermostat if it does not operate as specified:
- Vehicles with 1.6L Zetec-SE/1.4L engine.
REFER to: Thermostat - 1.6L Zetec-SE (Sigma)/1.4L (303-03 Engine Cooling, Removal and Installation).
- Vehicles with 1.8L/2.0L/1.6L Zetec-E engine.
REFER to: Thermostat - 1.6L Zetec-E (Zetec)/1.8L Zetec-E (Zetec)/2.0L Zetec-E (Zetec) (303-03 Engine Cooling, Removal and Installation).
- Vehicles with 1.8L Diesel engine.
REFER to: Thermostat - 1.8L Diesel (303-03 Engine Cooling, Removal and Installation).
- Vehicles with 2.0L Duratec ST engine.
REFER to: Thermostat - 2.0L Duratec-ST (Zetec) (303-03 Engine Cooling, Removal and Installation).
- Carry out another road test from step 1 using the same criteria to confirm that the concern has been rectified.
- Using the WDS, clear the PCM keep alive memory (KAM) or electrically erasable programmable read only memory (EEPROM) so that new drive values can be learnt.
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