Contents Wiring diagrams Section: Cooling System (Mechanical) All sections

Engine Cooling: Diagnosis Ford Fusion I facelift

Inspection and Verification

WARNINGAlways allow the engine to cool before opening the cooling system. Do not unscrew the coolant pressure relief cap when the engine is operating or the cooling system is hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions may result in serious personal injury.

Note. The engine cooling system is filled with Motorcraft Premium Gold Engine Coolant. Mixing coolant types degrades the corrosion protection of Motorcraft Premium Gold Engine Coolant. Do not mix coolant types. Failure to follow these instructions may result in engine or cooling system damage.

Note. Vehicles equipped with a degas bottle system have the pressure relief cap on the degas bottle and no radiator cap. Vehicles equipped with a coolant expansion tank system have the pressure relief cap on the radiator.

  1. Verify the customer concern.
  2. Visually check the engine coolant level at the degas bottle or coolant expansion tank when the system is cold.
  3. Make sure the pressure relief cap is installed correctly.
  4. Record any cooling system DTCs retrieved. Refer to the PCM DTC chart in «Inspection and Verification»(ref-291897-S22335358722008073000000) .
  5. If the system coolant is filled correctly and no DTCs associated with fail-safe cooling are retrieved, verify the customer's concern by operating the engine to duplicate the condition.
  6. Inspect to determine if any of the following mechanical or electrical concerns apply. VISUAL INSPECTION CHART Mechanical Electrical Leaks or weeps at: Hoses Tubes Clamp joints Quick connect couplings (if equipped) Gaskets O-rings Thermostat housing Radiator Pressure relief cap Coolant pump Heater core (wet floor or coolant odor in vehicle) Heater control valve Heated throttle body (TB) or heated TB adapter (if equipped) Coolant crossover manifold assembly (if equipped) Oil cooler (if equipped) Degas bottle (if equipped) Coolant expansion tank (if equipped) Heated PCV (if equipped) Fuel pressure regulator coolant bowl (if equipped, natural gas engine) Cylinder block core plugs (if equipped) Cylinder head core plugs (if equipped) Block heater (if equipped) Inoperative or damaged: Electric cooling fan (if equipped) Electronically actuated fan clutch Electronically actuated fan clutch controller Wiring, connectors, relays or modules Engine coolant temperature (ECT) sensor (if equipped) Cylinder head temperature (CHT) sensor (if equipped) Intake air temperature (IAT) sensor (if equipped) Mass air flow (MAF) sensor Vehicle speed sensor (VSS) VISUAL INSPECTION CHART Mechanical Electrical Cracked or damaged: Hoses Tubes Hose clamps Heater control valve (if equipped) Thermostat housing Radiator Pressure relief cap Cooling fan Fan clutch (if equipped) Coolant pump Degas bottle (if equipped) Coolant expansion tank (if equipped) Oil cooler (if equipped) Coolant crossover manifold assembly (if equipped) Cylinder block core plugs (if equipped) Cylinder head core plugs (if equipped) Block heater (if equipped) Restricted airflow through the A/C condenser/radiator Drive belt loose, worn or installed incorrectly Broken or weak drive belt tensioner Excessive white or light gray exhaust smoke (may have burnt coolant odor) Coolant in engine oil Engine oil in coolant Coolant in automatic transmission fluid (if equipped) Automatic transmission fluid (if equipped) in coolant
  7. If the inspection reveals an obvious concern that can be readily identified, repair it as necessary. Test the system for normal operation.
  8. Inspect the coolant condition in the following sequence: Inspect the coolant color. If Motorcraft Premium Gold Engine Coolant has a clear or pale yellow color, this indicates higher water content than required. Test the engine coolant freezing point range with the Battery/Antifreeze Tester. The freezing point should be in the range -45°C to -23°C (-50°F to -10°F). If the vehicle is driven in cold climates less than -36°C (-34°F), it may be necessary to increase the coolant concentration to get adequate freeze protection. Recommended coolant concentration is 50/50 ethylene glycol to distilled water. A pale green color indicates incorrect coolant (green in color) may have been added to the system. Use of incorrect (green in color) coolant degrades the corrosion protection of Motorcraft Premium Gold Engine Coolant. Flush the system and refill with the correct mixture of distilled water and Motorcraft Premium Gold Engine Coolant. NOTE: If Cooling System Stop Leak Pellets are used, darkening of the Motorcraft Premium Gold Engine Coolant from yellow to golden tan will occur. Dark brown could indicate a commercially available stop leak may have been used. Flush the system and refill with the correct mixture of distilled water and Motorcraft Premium Gold Engine Coolant. A light or reddish brown color indicates that rust may be present in the cooling system. Flush the system and refill with the correct mixture of distilled water and Motorcraft Premium Gold Engine Coolant. An iridescent sheen on top of the coolant could indicate a trace of oil is entering the system. For information on engine diagnosis, refer to «ENGINE SYSTEM - GENERAL INFORMATION»(ref-291856) article. A milky brown color may indicate that engine oil is entering the cooling system. Pressure test the cooling system. Refer to «Component Tests»(ref-291897-S21906288282008073000000) . If engine oil is suspected, the cause of the leak may be internal to the engine. Refer to «ENGINE SYSTEM - GENERAL INFORMATION»(ref-291856) article. A red, orange or light green colored sheen on top of the coolant may indicate that transmission fluid is entering the cooling system. The cause may be a leaky radiator. Pressure test the cooling system. Refer to the «Component Tests»(ref-291897-S21906288282008073000000) . If the engine coolant appearance is acceptable, test the engine coolant freezing point range with the Battery/Antifreeze Tester. The freezing point should be in the range -45°C to -23°C (-50°F to -10°F). If the vehicle is driven in cold climates less than -36°C (-34°F), it may be necessary to increase the coolant concentration to get adequate freeze protection. Recommended coolant concentration is 50/50 ethylene glycol to distilled water. Maximum coolant concentration is 60/40 for cold weather areas. Minimum coolant concentration is 40/60 for warm weather areas. Adjust coolant range and level if necessary: If coolant is low, add specified coolant mixture only. If the engine coolant tests too weak, remove some of the engine coolant and add undiluted engine coolant until the readings are within acceptable levels. If the engine coolant tests strong, remove some of the engine coolant and add distilled water until the readings are within acceptable levels.
  9. If an obvious cause for an observed or reported concern is found, correct the cause and test the system for normal operation before proceeding to the next step.
  10. If the cause is not visually evident, connect the scan tool to the data link connector (DLC).
  11. If the scan tool does not communicate with the VCM: check the VCM connection to the vehicle. check the scan tool connection to the VCM. refer to «MODULE COMMUNICATIONS NETWORK»(ref-291879) article, No Power To The Scan Tool, to diagnose no communication with the scan tool.
  12. If the scan tool does not communicate with the vehicle: verify the ignition key is in the ON position. verify the scan tool operation with a known good vehicle. refer to «MODULE COMMUNICATIONS NETWORK»(ref-291879) article to diagnose no response from the PCM.
  13. Carry out the network test. If the scan tool responds with no communication for one or more modules, refer to «MODULE COMMUNICATIONS NETWORK»(ref-291879) article. If the network test passes, retrieve and record continuous memory DTCs.
  14. Clear the continuous DTCs and carry out the self-test diagnostics PCM.
  15. If the DTCs recovered are related to the concern, go to the PCM DTC Chart. For all other DTCs, refer to «MULTIFUNCTION ELECTRONIC MODULES»(ref-291878) article.
  16. If no DTCs related to the concern are retrieved, go to «Symptom Chart»(ref-291897-S30748025242008073000000) .
DTCDescriptionAction
P0217Engine Coolant Overtemperature ConditionGo to Pinpoint Test B .
P1285Cylinder Head Overtemperature ConditionGo to Pinpoint Test B .
P1299Cylinder Head Overtemperature Protection ActiveGo to Pinpoint Test B .
P0125Insufficient Coolant Temp For Closed Loop Fuel ControlGo to Pinpoint Test C .
P0128Coolant Thermostat (Coolant Temp Below Thermostat Regulating Temperature)Go to Pinpoint Test C .
P0480 P0481 P0482Fan 1, 2 or 3 Control Circuit, RespectivelyREFER to the Introduction - Gasoline Engines article.
All Other DTCsREFER to the Introduction - Gasoline Engines article.

PCM DTC CHART

Symptom Chart

ConditionPossible SourcesAction
Loss of coolantCoolant hoses or tubes Hose clamps Coolant pump O-ring seal or gasket Thermostat O-ring seal or gasket Thermostat housing Radiator Transmission fluid cooler (in radiator) (if equipped) (may leak internally or externally) Degas bottle (if equipped) Coolant expansion tank (if equipped) Pressure relief cap Coolant pump leaking from weep hole Auxiliary coolant pump (if equipped) Heater core Heater control valve (if equipped) Coolant crossover manifold assembly (if equipped) Engine gaskets (may leak internally or externally) Oil cooler (if equipped) (may leak internally or externally) Heated throttle body (TB) or heated TB adapter (if equipped) Heated PCV (if equipped) Fuel pressure regulator coolant bowl (if equipped, natural gas engine) Cylinder block core plugs (if equipped) Cylinder head core plugs (if equipped) Block heater (if equipped)Go to Pinpoint Test A .
The engine overheatsLow coolant level External engine coolant leak Air lock in system Pressure relief cap installation Restricted airflow through the A/C condenser/radiator Internal engine coolant leak Coolant condition/concentration Accessory drive components Non-OEM engine enhancement components Electric cooling fan (if equipped) Mechanical cooling fan (if equipped) Mechanical cooling fan clutch (if equipped) Radiator Thermostat Engine coolant temperature (ECT) indicator system (gauge) ECT sensor (if equipped) Cylinder head temperature (CHT) sensor (if equipped) Heater core Coolant pump Coolant flow restrictionGo to Pinpoint Test B .
The engine does not reach normal operating temperatureLow coolant level Thermostat Mechanical fan clutch always engaged Electric cooling fan always on Engine coolant temperature indicator system (gauge) ECT sensor (if equipped) CHT sensor (if equipped)Go to Pinpoint Test C .
The block heater does not operate correctlyBlock heater power cableCHECK continuity in all 3 power cable circuits. If any circuit measures greater than 5 ohms, INSTALL a new power cable.
Block heaterCHECK the resistance of the block heater. If the resistance does not measure between 12.5 and 17 ohms, INSTALL a new block heater.
The electric cooling fan(s) or electronically controlled fan clutch is inoperative in one or more speeds or does not operate correctly (if equipped)Wiring Relays Fuses Fan control module Cooling fan motor(s) Cooling fan resistor(s) Electric fan clutchREFER to the Introduction - Gasoline Engines article.
The electric cooling fan(s) stay(s) on all the time (if equipped)Wiring RelaysREFER to the Introduction - Gasoline Engines article.
Noisy electric cooling fan operation (if equipped)Foreign material contamination Fan motorREMOVE the foreign material from the cooling fan and shroud. TEST the system for normal operation. If still noisy, INSTALL a new cooling fan assembly.
Fan blade detached from fan motorINSTALL a new cooling fan assembly.
Noisy mechanical fan operation (if equipped)Fan clutchCARRY OUT the Fan Clutch Test - Minimum Speed Requirement component test.

Symptom Chart

PINPOINT TEST A: LOSS OF COOLANT

WARNINGAlways allow the engine to cool before opening the cooling system. Do not unscrew the coolant pressure relief cap when the engine is operating or the cooling system is hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions may result in serious personal injury.
  1. A1 CARRY OUT INSPECTION AND VERIFICATION Carry out the «Inspection and Verification»(ref-291897-S22335358722008073000000) . Were any concerns found? YES : REPAIR as needed. TEST the system for normal operation. NO : Go to A2 .
  2. A2 CHECK THE ENGINE COOLANT LEVEL NOTE: Allow the engine to cool before checking the engine coolant level. Key in OFF position. Visually inspect the engine coolant level at the degas bottle or the coolant expansion tank. Is the engine coolant level within specifications? YES : Go to A3 . NO : ADJUST the engine coolant level as necessary. Go to A3 .
  3. A3 PRESSURE TEST THE ENGINE COOLING SYSTEM Pressure test the engine cooling system. Refer to «Pressure Test - Coolant Expansion Tank Systems»(ref-291897-S29331732622008073000000) . Does the engine cooling system leak? YES : REPAIR or INSTALL new components. TEST the system for normal operation. NO : If the vehicle is equipped with a coolant expansion tank, go to A4 . If the vehicle is equipped with a degas bottle, go to A5 .
  4. A4 CHECK THE PRESSURE RELIEF CAP Carry out the pressure relief cap pressure test. Refer to «Cap»(ref-291897-S02370050352008073000000) . Is the pressure relief cap OK? YES : Go to A5 . NO : INSTALL a new pressure relief cap. TEST the system for normal operation.
  5. A5 CHECK THE ENGINE COOLANT FOR AN INTERNAL LEAK Inspect the engine coolant in the degas bottle or coolant expansion tank for signs of engine oil or transmission fluid. Is engine oil or transmission fluid evident in the coolant? YES : If engine oil is evident, go to «ENGINE SYSTEM - GENERAL INFORMATION»(ref-291856) article for engine diagnosis. If transmission fluid is evident, INSTALL a new radiator. REPAIR the transmission as necessary. Refer to the appropriate Automatic Transmission article for the procedure. TEST the system for normal operation. NO : Go to A6 .
  6. A6 CHECK THE ENGINE OIL AND TRANSMISSION FLUID FOR COOLANT Remove the oil level indicators from the engine and the transmission. Is coolant evident in the oil or transmission fluid? YES : If coolant is in the engine oil, go to «ENGINE SYSTEM - GENERAL INFORMATION»(ref-291856) article. If coolant is in the transmission fluid, INSTALL a new radiator. REPAIR the transmission as necessary. Refer to the appropriate Automatic Transmission article for the procedure. NO : Go to A7 .
  7. A7 CHECK THE COOLING SYSTEM FOR COMBUSTION GASES NOTE: Use U-View® Combustion Leak Tester part number 560000 or equivalent. Using a cooling system combustion gas leak tester, following the instructions supplied with the tester, check the coolant for combustion gases. Are combustion gases present? YES : Go to «ENGINE SYSTEM - GENERAL INFORMATION»(ref-291856) article for engine diagnosis. NO : The cooling system is operational.

PINPOINT TEST B: THE ENGINE OVERHEATS

WARNINGAlways allow the engine to cool before opening the cooling system. Do not unscrew the coolant pressure relief cap when the engine is operating or the cooling system is hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions may result in serious personal injury.
  1. B1 CARRY OUT INSPECTION AND VERIFICATION Carry out the «Inspection and Verification»(ref-291897-S22335358722008073000000) . Were any concerns found? YES : REPAIR as needed. TEST the system for normal operation. NO : Go to B2 .
  2. B2 CHECK FOR DTCs NOTE: Refer to the «Introduction - Gasoline Engines»(ref-291242) article for correct scan tool hook-up procedure. Check for DTC P0217, P1285 or P1299. Is DTC P0217, P1285 or P1299 present? YES : Go to B3 . NO : Actual engine overheating has not been verified. CHECK the ECT gauge operation. REFER to «INSTRUMENT CLUSTER (IC), MESSAGE CENTER, AND WARNING CHIMES»(ref-291880) article. If any other DTCs are retrieved, REFER to the «Introduction - Gasoline Engines»(ref-291242) article.
  3. B3 CHECK FOR AN AIRFLOW OBSTRUCTION Check the radiator or A/C condenser for an external obstruction such as leaves or cardboard. Is an obstruction present? YES : REMOVE the obstruction. TEST the system for normal operation. NO : Go to B4 .
  4. B4 CHECK THE ENGINE COOLANT LEVEL NOTE: Allow the engine to cool before checking the coolant level. Key in OFF position. Visually check the engine coolant level in the degas bottle or coolant expansion tank. Is the engine coolant level within specification? YES : Go to B5 . NO : ADJUST the engine coolant level as necessary. Go to B5 .
  5. B5 PRESSURE TEST THE ENGINE COOLING SYSTEM Pressure test the engine cooling system. Refer to «Pressure Test - Coolant Expansion Tank Systems»(ref-291897-S29331732622008073000000) . Does the engine cooling system leak? YES : REPAIR or INSTALL new components. TEST the system for normal operation. NO : Vehicles equipped with an expansion tank, go to B6 . Vehicles equipped with a degas bottle, go to B7 .
  6. B6 CHECK THE PRESSURE RELIEF CAP Carry out the pressure relief cap pressure test. Refer to «Cap»(ref-291897-S02370050352008073000000) . Is the pressure relief cap OK? YES : Go to B7 . NO : INSTALL a new pressure relief cap. TEST the system for normal operation.
  7. B7 CHECK THE ENGINE COOLANT FOR AN INTERNAL LEAK Inspect the engine coolant in the degas bottle or coolant expansion tank for signs of engine oil or transmission fluid. Is engine oil or transmission fluid evident in the coolant? YES : If engine oil is evident, go to «ENGINE SYSTEM - GENERAL INFORMATION»(ref-291856) article for engine diagnosis. If transmission fluid is evident, INSTALL a new radiator. REPAIR the transmission as necessary. Refer to the appropriate Automatic Transmission article for the procedure. TEST the system for normal operation. NO : Go to B8 .
  8. B8 CHECK THE ENGINE OIL AND TRANSMISSION FLUID FOR COOLANT Remove the oil level indicators from the engine and the transmission. Is coolant evident in the oil or transmission fluid? YES : If coolant is in the engine oil, go to «ENGINE SYSTEM - GENERAL INFORMATION»(ref-291856) article. If coolant is in the transmission fluid, INSTALL a new radiator. REPAIR the transmission as necessary. Refer to the appropriate Automatic Transmission article for the procedure. NO : Go to B9 .
  9. B9 CHECK THE COOLING SYSTEM FOR COMBUSTION GASES NOTE: Use U-View® Combustion Leak Tester part number 560000 or equivalent. Using a cooling system combustion gas leak tester, following the instructions supplied with the tester, check the coolant for combustion gases. Are combustion gases present? YES : Go to «ENGINE SYSTEM - GENERAL INFORMATION»(ref-291856) article for engine diagnosis. NO : Go to B10 .
  10. B10 CHECK COOLANT CONDITION Check the coolant for dirt, rust or contamination and check the coolant concentration. Is the coolant condition OK? YES : Vehicles equipped with an electric cooling fan, go to B11 . Vehicles equipped with only a mechanical cooling fan, go to B12 . NO : FLUSH the engine cooling system. REFER to «Cooling System Flushing»(ref-291897-S31962513222008073000000) . TEST the system for normal operation.
  11. B11 CHECK THE ELECTRIC COOLING FAN OPERATION Start the engine. Place the climate control function selector in the MAX A/C position and the blower motor switch in the HI position. Did the electric cooling fan operate? YES : If the vehicle is also equipped with a mechanical cooling fan, go to B12 . Otherwise, go to B13 . NO : DIAGNOSE the electric cooling fan operation. REFER to «Introduction - Gasoline Engines»(ref-291242) article.
  12. B12 CHECK THE MECHANICAL COOLING FAN OPERATION Key in OFF position. If the vehicle is equipped with a viscous fan clutch, carry out the «Fan Clutch Test»(ref-291897-S14841497482008073000000) . If the vehicle is equipped with an electronically actuated fan clutch, refer to the «Introduction - Gasoline Engines»(ref-291242) article. Is the cooling fan operation OK? YES : Go to B13 . NO : INSTALL a new fan clutch. TEST the system for normal operation.
  13. B13 CHECK THE COOLANT PUMP OPERATION Start the engine. Allow the engine to run for 10 minutes (hot side thermostat equipped vehicles) or 30 minutes (cold side thermostat equipped vehicles). Place the climate control function selector in the MAX HEAT position. Feel the heater outlet hose. Is the heater outlet hose hot? YES : Go to B14 . NO : INSTALL a new coolant pump. TEST the system for normal operation.
  14. B14 CHECK THE THERMOSTAT OPERATION Start the engine. Allow the engine to run for 10 minutes (hot side thermostat equipped vehicles) or 30 minutes (cold side thermostat equipped vehicles). Feel the upper radiator hose (hot side thermostat equipped vehicles) or the lower radiator hose (cold side thermostat equipped vehicles). Is the upper (hot side thermostat equipped vehicles) or lower (cold side equipped vehicles) radiator hose hot? YES : CHECK the engine coolant temperature gauge operation. REFER to «INSTRUMENT CLUSTER (IC), MESSAGE CENTER, AND WARNING CHIMES»(ref-291880) article. NO : Go to B15 .
  15. B15 VISUALLY INSPECT THE THERMOSTAT Carry out the «Thermostat Visual Inspection»(ref-291897-S29977181202008073000000) . Is the thermostat damaged? YES : INSTALL a new thermostat. TEST the system for normal operation. NO : INSTALL a new thermostat. TEST the system for normal operation. If the engine still overheats, INSTALL a new radiator. TEST the system for normal operation.

PINPOINT TEST C: THE ENGINE DOES NOT REACH NORMAL OPERATING TEMPERATURE

WARNINGAlways allow the engine to cool before opening the cooling system. Do not unscrew the coolant pressure relief cap when the engine is operating or the cooling system is hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions may result in serious personal injury.
  1. C1 CARRY OUT INSPECTION AND VERIFICATION Carry out the «Inspection and Verification»(ref-291897-S22335358722008073000000) . Were any concerns found? YES : REPAIR as needed. TEST the system for normal operation. NO : Go to C2 .
  2. C2 CHECK FOR DTCs P0125 or P0128 NOTE: Refer to the «Introduction - Gasoline Engines»(ref-291242) article for correct scan tool hook-up procedure. Check for DTC P0125 or P0128. Is DTC P0125 or P0128 present? YES : If the vehicle is equipped with an electric cooling fan, go to C3 . If the vehicle is equipped with only a mechanical cooling fan, go to C4 . NO : The cooling system is operational. If an inoperative engine coolant temperature gauge is suspected, CHECK the engine coolant temperature gauge operation. REFER to «INSTRUMENT CLUSTER (IC), MESSAGE CENTER, AND WARNING CHIMES»(ref-291880) article. If an inoperative climate control system is suspected, CHECK the climate control system operation. REFER to «CLIMATE CONTROL SYSTEM - GENERAL INFORMATION AND DIAGNOSTICS»(ref-291859) article. If any other DTCs are retrieved, REFER to the «Introduction - Gasoline Engines»(ref-291242) article.
  3. C3 CHECK THE ELECTRIC COOLING FAN OPERATION Allow the engine to cool. Make sure the A/C switch is OFF (if equipped). Start the engine. Check the electric cooling fan. Is the electric cooling fan on all the time? YES : DIAGNOSE the electric cooling fan operation. REFER to the «Introduction - Gasoline Engines»(ref-291242) article. NO : If the vehicle is also equipped with a mechanical cooling fan, go to C4 . Otherwise, go to C5 .
  4. C4 CHECK THE MECHANICAL COOLING FAN OPERATION Carry out the Cooling Fan Clutch Component Test. For a mechanical cooling fan clutch, refer to «Component Tests»(ref-291897-S21906288282008073000000) . For an electronic cooling fan clutch, refer to the «Introduction - Gasoline Engines»(ref-291242) article. Is the cooling fan clutch OK? YES : Go to C5 . NO : INSTALL a new cooling fan clutch. TEST the system for normal operation.
  5. C5 CHECK THE COOLANT LEVEL NOTE: Allow the engine to cool before checking the coolant level. Visually check the engine coolant level in the degas bottle or coolant expansion tank. Is the engine coolant level within specification? YES : INSTALL a new thermostat. TEST the system for normal operation. NO : Go to «Pinpoint Test A»(ref-291897-S32480736212008073000000) to diagnose a coolant leak.

Pressure Test - Degas Bottle Systems

WARNINGAlways allow the engine to cool before opening the cooling system. Do not unscrew the coolant pressure relief cap when the engine is operating or the cooling system is hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions may result in serious personal injury.

Note. Vehicles equipped with a degas bottle system have the pressure relief cap on the degas bottle and no radiator cap. Vehicles equipped with a coolant expansion tank system have the pressure relief cap on the radiator.

  1. Turn the engine OFF.
  2. Check the engine coolant level. Adjust the coolant level as necessary.
  3. Attach the Radiator/Heater Core Pressure Tester to the degas bottle nipple and overflow hose. Install a pressure test pump to the quick connect fitting of the test adapter.
  4. Slowly depress the plunger of the pressure test pump until the pressure gauge reading stops increasing and note the highest pressure reading obtained. If the pressure reading exceeds the maximum cap pressure listed in the specifications table, install a new pressure relief cap.
  5. If the system does not hold pressure, remove the pressure relief cap and wash in clean water to dislodge all the foreign material from the gasket. Check the sealing surface in the filler neck of the degas bottle for nicks or cuts. Install the pressure relief cap.
  6. Pressurize the engine cooling system as described in Step 4 above. Observe the gauge reading for approximately 2 minutes. Pressure should not drop during this time. If the pressure drops within this time, inspect for leaks and repair as necessary.
  7. If no leaks are found and the pressure drops. the pressure relief cap may be leaking. Install a new pressure relief cap and retest the system.
  8. If no leaks are found after a new pressure relief cap is installed, and the pressure drops, the leak may be internal to the radiator transmission cooler (if equipped). Inspect the coolant for transmission fluid and the transmission fluid for coolant. Repair as necessary.
  9. If there is no contamination of the coolant or transmission fluid, the leak may be internal to the engine. Inspect the coolant for engine oil and the engine oil for coolant. Refer to «ENGINE SYSTEM - GENERAL INFORMATION»(ref-291856) article to diagnose the engine.
  10. Release the system pressure by loosening the pressure relief cap. Check the coolant level and adjust as necessary.

Pressure Test - Coolant Expansion Tank Systems

WARNINGAlways allow the engine to cool before opening the cooling system. Do not unscrew the coolant pressure relief cap when the engine is operating or the cooling system is hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Failure to follow these instructions may result in serious personal injury.

Note. Vehicles equipped with a degas bottle system have the pressure relief cap on the degas bottle and no radiator cap. Vehicles equipped with a coolant expansion tank system have the pressure relief cap on the radiator.

  1. Turn the engine OFF.
  2. Remove the pressure relief cap. Top off the radiator as needed. Fit the pressure tester to the radiator fill neck.
  3. Pump the cooling system to a maximum of 138 kPa (20 psi) and hold for 2 minutes. If the pressure drops within this time, inspect for leaks and repair as necessary.
  4. If no leaks are found and the pressure drops, the leak may be internal to the radiator transmission cooler (if equipped). Inspect the coolant for transmission fluid and the transmission fluid for coolant. Repair as necessary.
  5. If there is no contamination of the coolant or transmission fluid, the leak may be internal to the engine. Inspect the coolant for engine oil and the engine oil for coolant. Refer to «ENGINE SYSTEM - GENERAL INFORMATION»(ref-291856) article to diagnose the engine.

Thermostat Visual Inspection

  1. Remove the thermostat.
  2. Examine the thermostat for signs of damage including: Valve not fully seated (light visible through the valve) Foreign material lodged in the main valve Bent or broken frame or flange Bent or broken spring Bent or broken valve or valve stem Wax leaking from wax reservoir or a bulge in the reservoir Any other damage or distortion
  3. If damage is found during the inspection, remove any foreign material or broken pieces and install a new thermostat.
  4. If no damage is found during the inspection, continue troubleshooting the system concern. Go to the Symptom Chart for further instructions.

Radiator Leak Test, Removed From Vehicle

Note. Never leak test an aluminum radiator in the same water that copper/brass radiators are tested in. Flux and caustic cleaners may be present in the cleaning tank and they will damage aluminum radiators.

Note. Always install plugs in the oil cooler fittings before leak testing or cleaning any radiator.

Note. Clean the radiator before leak testing to avoid contamination of tank.

  1. Leak test the radiator in clean water with 138 kPa (20 psi) air pressure.

Fan Clutch Test

  1. Turn the engine OFF and wait until the fan comes to a complete stop.
  2. Spin the fan blade by hand. A light resistance should be felt. If there is no resistance or very high resistance, the minimum and maximum fan speeds must be checked. For an electronically actuated fan clutch, refer to the «Introduction - Gasoline Engines»(ref-291242) article. For a viscous fan clutch, carry out the following

Fan Clutch Test - Minimum Speed Requirement

  1. Use a suitable marker to mark the coolant pump or fan pulley and one of the fan blades.
  2. Make sure the A/C is OFF, if equipped.
  3. Start the engine and run it at approximately 2,000 RPM for 5 minutes or until there is a noticeable reduction in fan noise to allow the fan clutch to go into disengaged mode.
  4. Aim a laser photo tachometer at the coolant pump or fan pulley. Run the engine to achieve 3,000 RPM at the coolant pump or fan pulley.
  5. With the coolant pump or fan pulley at 3,000 RPM, aim the laser photo tachometer at the fan blade. Monitor and record fan speed.
  6. The fan blade speed must be less than the specified RPM at 3,000 RPM coolant pump or fan pulley RPM. Refer to «SPECIFICATIONS»(ref-291897-S11066163982008073000000) for correct fan speed.
  7. Turn the engine off.
  8. If the fan blade speed was greater than specified, install a new fan clutch.

Fan Clutch Test - Maximum Speed Requirement

  1. Use a suitable marker to mark the coolant pump or fan pulley and one of the fan blades.
  2. Block off areas on each side of the radiator in the engine compartment, the front of the radiator grille and the bumper. Close the hood. This will raise the temperature of the air striking the fan clutch and should cause the fan blade to operate at maximum speed.
  3. Place the climate control function selector switch in the MAX A/C position and the blower motor switch in the HI position, if equipped.
  4. Start the engine and run it at approximately 2,000 RPM until normal operating temperature has been achieved. Using an infrared thermometer, monitor the coolant pump or fan pulley. Run the engine until the coolant pump or fan pulley is at least 96°C (205°F).
  5. Aim a laser photo tachometer at the coolant pump or fan pulley. Run the engine to achieve 3,000 RPM at the coolant pump or fan pulley.
  6. With the coolant pump or fan pulley at 3,000 RPM, aim the laser photo tachometer at the fan blade. Monitor and record fan blade speed.
  7. The fan blade speed must be greater than the specified RPM at 3,000 RPM coolant pump or fan pulley RPM. Refer to «SPECIFICATIONS»(ref-291897-S11066163982008073000000) for correct fan speed.
  8. Open the hood and allow the engine to idle momentarily to lower engine temperature. Turn the engine off and remove the blocks from the radiator, grille and bumper.
  9. If the fan blade speed is less than specified, install a new fan clutch.