Engine Cooling System: Diagnosis Mercury Monterey VIII

Inspection and Verification

1. Verify the customer concern by operating the engine to duplicate the condition.
2. Inspect to determine if any of the following mechanical or electrical concerns apply. VISUAL INSPECTION CHART Mechanical Electrical Leaks Restricted airflow through the condenser/radiator Damaged hoses Loose/damaged hose clamps Damaged coolant gasket Damaged head gaskets Damaged coolant pump Damaged radiator Damaged degas bottle Damaged heater core Damaged or obstructed electric cooling fan Damaged cylinder head temperature sensor Damaged wiring Fuse Damaged circuitry CAUTION: The cylinder head temperature sensor is not reusable after removal. For electrical concern testing, See «INTRODUCTION - GASOLINE»(ref-229953) article.
3. If the inspection reveals an obvious concern that can be readily identified, repair it as necessary.
4. Inspect the coolant condition: Inspect the coolant color. If Motorcraft Premium Gold Engine Coolant VC-7-A (in California, Oregon and New Mexico VC-7-B, in Canada CVC-7-A) or equivalent meeting Ford specification WSS-M97B51-A1 (yellow color) has a clear or pale yellow color, this indicates higher water content than required. Dark brown could indicate unauthorized stop leak may have been used. Use Cooling System Stop Leak Pellets VC-6 or equivalent meeting Ford specification WSS-M99B37-B6. 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 water and Premium Gold Engine Coolant. An iridescent sheen on the surface of the coolant could indicate a trace of oil is entering the system. For additional information on engine diagnosis, refer to «ENGINE SYSTEM-GENERAL INFORMATION»(ref-234502) . A milky brown color may indicate that engine oil is entering the cooling system. If oil is suspected, the cause of the leak may be internal to the engine. For additional information on engine diagnosis, refer to «ENGINE SYSTEM-GENERAL INFORMATION»(ref-234502) . A milky brown color in the engine oil may indicate that coolant is entering the oil. If coolant is suspected, the cause of the leak may be internal to the engine. For additional information on engine diagnosis, refer to «ENGINE SYSTEM-GENERAL INFORMATION»(ref-234502) . 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 (-50°F) to 23°C (-10°F). If the vehicle is driven in cold climates less than -37°C (-34°F), it may be necessary to increase the coolant concentration to get adequate freeze protection. Maximum coolant concentration is 60/40. Minimum coolant concentration is 40/60. Adjust coolant range and level if necessary: If the coolant is low, add specified coolant mixture only. If the coolant tests weak, add straight engine coolant until the readings are within acceptable levels. If the coolant tests strong, remove some of the engine coolant and add distilled water until the readings are within acceptable levels. If the concern remains after the inspection, determine the symptom(s). GO to «SYMPTOM CHART»(ref-234494-S01389277032006061000000) . Verify the cooling system is correctly filled and bled. For additional information, refer to «COOLING SYSTEM DRAINING, FILLING AND BLEEDING»(ref-234494-S34432732002006061000000) .

Powertrain Control Module Diagnostic Trouble Code (DTC) Index

DIAGNOSTIC TROUBLE CODE INDEX

Symptom Chart

SYMPTOM CHART

PINPOINT TEST A: LOSS OF ENGINE COOLANT

1. A1 CHECK THE ENGINE COOLANT LEVEL WARNING: Never remove the pressure relief cap while the engine is operating or when the cooling system is hot. Failure to follow these instructions can result in damage to the cooling system or engine or personal injury. To avoid having scalding hot coolant or steam blow out of the degas bottle when removing the pressure relief cap, wait until the engine has cooled, then wrap a thick cloth around the pressure relief cap and turn it slowly. Step back while the pressure is released from the cooling system. When you are sure all the pressure has been released, turn and remove the pressure relief cap (still with a cloth). NOTE: Allow the engine to cool before checking the engine coolant level. Key in OFF position. Visually check the engine coolant level at the degas bottle. Is the engine coolant level within specification? Yes : GO to A2 . No : REFILL the engine coolant as necessary. GO to A2 .
2. A2 CHECK THE DEGAS BOTTLE PRESSURE RELIEF CAP WARNING: To avoid personal injury, do not unscrew the coolant pressure relief cap while the engine is operating or hot. The cooling system is under pressure; steam and hot liquid can come out forcefully when the cap is loosened slightly. Inspect the pressure relief cap for foreign material between the sealing gasket and the diaphragm. Is the pressure relief cap OK? Yes : GO to A3 . No : INSTALL a new pressure relief cap. TEST the system for normal operation.
3. A3 CHECK THE ENGINE COOLANT FOR INTERNAL LEAK WARNING: Never remove the pressure relief cap while the engine is operating or when the cooling system is hot. Failure to follow these instructions can result in damage to the cooling system or engine or personal injury. To avoid having scalding hot coolant or steam blow out of the degas bottle when removing the pressure relief cap, wait until the engine has cooled, then wrap a thick cloth around the pressure relief cap and turn it slowly. Step back while the pressure is released from the cooling system. When you are sure all the pressure has been released, turn and remove the pressure relief cap (still with a cloth). Inspect the engine coolant in the degas bottle for signs of transmission fluid or engine oil. Is oil or transmission fluid evident in coolant? Yes : If engine oil is evident, GO to «ENGINE SYSTEM-GENERAL INFORMATION»(ref-234502) . If transmission fluid is evident, INSTALL a new radiator as necessary. No : GO to A4 .
4. A4 CHECK THE ENGINE AND THE TRANSMISSION FOR COOLANT Remove the oil level dipsticks from the engine and the transmission. Is coolant evident in oil or transmission fluid? Yes : If coolant is in the engine oil, GO to «ENGINE SYSTEM-GENERAL INFORMATION»(ref-234502) . If coolant is in the transmission fluid, INSTALL a new radiator. REFER to «RADIATOR»(ref-234494-S35399121402006061000000) . REPAIR the transmission as necessary, REFER to «AUTOMATIC TRANSAXLE/TRANSMISSION»(ref-234499) . No : GO to A5 .
5. A5 PRESSURE TEST THE ENGINE COOLING SYSTEM Pressure test the cooling system. Refer to «PRESSURE TEST»(ref-234494-S16996602332006061000000) . Does the engine cooling system leak? Yes : REPAIR or INSTALL new components if leaking. TEST the system for normal operation. No : The cooling system is operational. GO to «SYMPTOM CHART»(ref-234494-S01389277032006061000000) .

PINPOINT TEST B: THE ENGINE OVERHEATS

1. B1 CHECK THE ENGINE COOLANT LEVEL NOTE: If the engine is hot, allow the engine to cool before proceeding. Key in OFF position. WARNING: Never remove the pressure relief cap while the engine is operating or when the cooling system is hot. Failure to follow these instructions can result in damage to the cooling system or engine or personal injury. To avoid having scalding hot coolant or steam blow out of the degas bottle when removing the pressure relief cap, wait until the engine has cooled, then wrap a thick cloth around the pressure relief cap and turn it slowly. Step back while the pressure is released from the cooling system. When you are sure all the pressure has been released, turn and remove the pressure relief cap (still with a cloth). Check the engine coolant level at the degas bottle. Is the engine coolant OK? Yes : GO to B2 . No : REFILL the engine coolant at the degas bottle. GO to «PINPOINT TEST A»(ref-234494-S01510622542006061000000) .
2. B2 CHECK THE COOLANT CONDITION Check the coolant for contaminants such as rust, corrosion, or discoloration. Is the coolant condition OK? Yes : GO to B3 . No : FLUSH the engine cooling system. TEST the system for normal operation.
3. B3 CHECK FOR AN AIRFLOW OBSTRUCTION Inspect the A/C condenser core and radiator for obstructions such as leaves or dirt. Is there an obstruction? Yes : REMOVE the obstruction. CLEAN the A/C condenser core and radiator. TEST the system for normal operation. No : GO to B4 .
4. B4 CHECK THE THERMOSTAT OPERATION Key in START position. Start the engine and allow it to run until the engine reaches operating temperature. Feel the inlet and outlet heater water hoses and the underside of the upper radiator hose. Are the upper radiator hose and the heater hoses cold? Yes : INSTALL a new thermostat. TEST the system for normal operation. No : GO to B5 .
5. B5 CHECK THE COOLING FAN OPERATION Using the diagnostic tool, command the cooling fans ON in low, medium and high speed. Do the cooling fans operate correctly? Yes : INSTALL a new coolant pump. TEST the system for normal operation. No : GO to «SYMPTOM CHART»(ref-234494-S01389277032006061000000) to diagnose cooling fans.

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

1. C1 CHECK THE ENGINE TEMPERATURE Key in START position. Start the engine and allow the engine to idle for 10 minutes. Key in OFF position. Feel the upper and lower radiator hoses. Are the upper and lower radiator hoses cold? Yes : INSTALL a new thermostat. TEST the system for normal operation. No : REFER to «INSTRUMENT CLUSTER AND PANEL ILLUMINATION»(ref-234536) for diagnosis and testing of the engine coolant temperature gauge.

Pinpoint Test D: The Electric Cooling Fan(s) Is Inoperative In One Or More Speeds

Refer to SYSTEM WIRING DIAGRAMS (Freestar) or SYSTEM WIRING DIAGRAMS (Monterey) for schematic and connector information.

Note. Before carrying out the following test, diagnose any PCM DTCs.

Scheme 5

Scheme 6

Scheme 7

Scheme 8

Scheme 9

Scheme 10

Scheme 11

Scheme 12

1. D1 CHECK OPERATION OF THE ELECTRIC COOLING FANS IN LOW AND MEDIUM Key in ON position. Connect the diagnostic tool. Using the diagnostic tool, command the cooling fans ON in low and medium speeds. Are both cooling fans inoperative in both speeds? Yes : CARRY OUT the cooling fan resistor component test in this article. If the resistor tests OK, GO to D2 . No : If both fans are inoperative in low speed only, REPAIR circuit 3850 (LG/VT)/1826 (YE/RD) for an open. TEST the system for normal operation. If the LH fan is inoperative in low speed only, REPAIR circuit 3850 (LG/VT)/1826 (YE/RD) for a short to ground. TEST the system for normal operation. If the RH fan is inoperative in low speed only, REPAIR circuit 3850 (LG/VT)/1826 (YE/RD) for a short to voltage. TEST the system for normal operation. GO to D3 .
2. D2 CHECK THE COOLING FAN RESISTOR GROUND CIRCUIT Key in OFF position. Disconnect: Cooling Fan Resistor C1214. Measure the resistance between cooling fan resistor C1214-1, circuit 1205 (BK) and ground. Is the resistance less than 5 ohms? Yes : REPAIR circuit 471 (OG/LG). TEST the system for normal operation. No : REPAIR circuit 1205 (BK). TEST the system for normal operation.
3. D3 CHECK OPERATION OF THE ELECTRIC COOLING FANS IN MEDIUM AND HIGH Using the diagnostic tool, command the cooling fans ON in medium and high speeds. Is only one cooling fan inoperative in both speeds? Yes : RH cooling fan, GO to D4 . LH cooling fan, GO to D8 . No : If both fans are inoperative in high speed only, REPAIR circuit 1205 (BK) for an open. TEST the system for normal operation. If one fan is inoperative in medium speed only, CARRY OUT the relay component test on cooling fan relay 4 (LH) or 5 (RH). If the relay tests OK, REPAIR circuit 471 (OG/LG) for an open. TEST the system for normal operation. If one fan is inoperative in high speed only, CARRY OUT the relay component test on cooling fan relay 4 (LH) or 5 (RH). If the relay tests OK, REPAIR circuit 1205 (BK) for an open. TEST the system for normal operation.
4. D4 CHECK THE VOLTAGE TO THE RH ELECTRIC COOLING FAN Key in OFF position. Disconnect: RH Cooling Fan Motor C1077. Key in ON position. Using the diagnostic tool, command the cooling fans ON in high speed. Measure the voltage between RH cooling fan motor C1077-1, circuit 1825 (LG/YE) and C1077-2, circuit 461 (OG). Is the voltage greater than 10 volts? Yes : INSTALL a new RH cooling fan motor. TEST the system for normal operation. No : GO to D5 .
5. D5 CHECK THE VOLTAGE TO THE RH ELECTRIC COOLING FAN Measure the voltage between RH cooling fan motor C1077-1, circuit 1825 (LG/YE) and ground. Is the voltage greater than 10 volts? Yes : GO to D7 . No : GO to D6 .
6. D6 CHECK CIRCUIT 1823 (YE/BK) Key in OFF position. Disconnect: Cooling Fan Relay 2. Key in ON position. Measure the voltage between the auxiliary relay box 1 cooling fan relay 2 pin 5, circuit 1823 (YE/BK) and ground. Is the voltage greater than 10 volts? Yes : CARRY OUT the relay component test on cooling fan relay 2. If the relay tests OK, REPAIR circuit 1825 (LG/YE) for an open. TEST the system for normal operation. No : REPAIR circuit 1823 (YE/BK) for an open. TEST the system for normal operation.
7. D7 CHECK CIRCUIT 3828 (OG/BK) Key in OFF position. Disconnect: Cooling Fan Relay 3. Key in ON position. Using the diagnostic tool, command the cooling fans ON in high speed. Measure the resistance between the auxiliary relay box 1 cooling fan relay 3 pin 87, circuit 3828 (OG/BK) and ground. Is the resistance less than 5 ohms? Yes : CARRY OUT the relay component test on cooling fan relay 3. If the relay tests OK, REPAIR circuit 461 (OG) for an open. TEST the system for normal operation. No : CARRY OUT the relay component test on cooling fan relay 5. If the relay tests OK, REPAIR circuit 3828 (OG/BK) for an open. TEST the system for normal operation.
8. D8 CHECK THE VOLTAGE TO THE LH ELECTRIC COOLING FAN Key in OFF position. Disconnect: LH Cooling Fan Motor C1074 or C1020. Key in ON position. Using the diagnostic tool, command the cooling fans ON in high speed. NOTE: Vehicles without trailer tow package. Measure the voltage between LH cooling fan motor C1020-2, circuit 1824 (LG/VT) and C1020-1, circuit 462 (VT). NOTE: Vehicles equipped with trailer tow package. Measuring Voltage Between LH Cooling Fan Motor C1074-1, Circuit 1824 (LG/VT) And C1074-2, Circuit 462 (VT). Is the voltage greater than 10 volts? Yes : INSTALL a new LH cooling fan motor. TEST the system for normal operation. No : GO to D9 .
9. D9 CHECK THE VOLTAGE TO THE LH ELECTRIC COOLING FAN NOTE: Vehicles without trailer tow package. Measure the voltage between LH cooling fan motor C1020-2, circuit 1824 (LG/VT) and ground. NOTE: Vehicles equipped with trailer tow package. Measure the voltage between LH cooling fan motor C1074-1, circuit 1824 (LG/VT) and ground. Is the voltage greater than 10 volts? Yes : CARRY OUT the relay component test on cooling fan relay 42. Refer to «COMPONENT TESTING»(ref-233794) for component testing. TEST the system for normal operation. No : GO to D10 .
10. D10 CHECK CIRCUIT 1822 (LB) Key in OFF position. Disconnect: Cooling Fan Relay 1. Key in ON position. Measure the voltage between the auxiliary relay box 1 cooling fan relay 2 pin 87, circuit 1822 (LB) and ground. Is the voltage greater than 10 volts? Yes : CARRY OUT the relay component test on cooling fan relay 1. If the relay tests OK, REPAIR circuit 1824 (LG/VT) for an open. TEST the system for normal operation. No : REPAIR circuit 1822 (LB) for an open. TEST the system for normal operation.

Pinpoint Test E: The Electric Cooling Fan(s) Stays On All The Time

Refer to SYSTEM WIRING DIAGRAMS (Freestar) or SYSTEM WIRING DIAGRAMS (Monterey) for schematic and connector information.

Note. Before carrying out the following test, diagnose any PCM DTCs.

1. E1 CHECK OPERATION OF THE ELECTRIC COOLING FANS Key in ON position. Observe fan operation. Is only one fan running? Yes : RH cooling fan, GO to E2 . LH cooling fan, GO to E3 . No : GO to «PINPOINT TEST F»(ref-234494-S36535403712006061000000) .
2. E2 CHECK CIRCUIT 1825 (LG/YE) FOR A SHORT TO VOLTAGE Key in OFF position. Disconnect: RH Cooling Fan Motor C1077. Key in ON position. Measure the voltage between RH cooling fan motor C1077-1, circuit 1825 (LG/YE) and ground. Is the voltage greater than 10 volts? Yes : REPAIR circuit 1825 (LG/YE) for a short to voltage. TEST the system for normal operation. No : INSTALL a new cooling fan relay 2. TEST the system for normal operation.
3. E3 CHECK CIRCUIT 1824 (LG/VT) FOR A SHORT TO VOLTAGE Key in OFF position. Disconnect: LH Cooling Fan Motor C1074. Key in ON position. NOTE: Vehicles without trailer tow package. Measure the voltage between LH cooling fan motor C1020-2, circuit 1824 (LG/VT) and ground. NOTE: Vehicles equipped with trailer tow package. Measure the voltage between LH cooling fan motor C1074-1, circuit 1824 (LG/VT) and ground. Is the voltage greater than 10 volts? Yes : REPAIR circuit 1824 (LG/VT) for a short to voltage. TEST the system for normal operation. No : INSTALL a new cooling fan relay 1. TEST the system for normal operation.

Pressure Test

1. Turn the engine OFF.
2. Check the engine coolant level. Refer to «COOLING SYSTEM DRAINING, FILLING AND BLEEDING»(ref-234494-S34432732002006061000000) .
3. Connect 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.
5. If the pressure relief cap does not hold pressure, remove and wash the pressure relief cap in clean water to dislodge all foreign particles from the gaskets. Check the sealing surface in the filler neck.
6. If 89 kPa (13 psi) cannot be reached, carry out the pressure relief cap component test. If more than 124 kPa (18 psi) shows on the gauge, install a new pressure relief cap.
7. Pressurize the engine cooling system as described in Step 4 (using a pressure relief cap that operates within the specified upper and lower pressure limits). Observe the gauge reading for approximately 2 minutes; refer to «GENERAL SPECIFICATIONS»(ref-234494-S33676672452006061000000) . Pressure should not drop during this time.
8. Release the system pressure by loosening the pressure relief cap. Check the engine coolant level and replenish, if necessary, with the correct engine coolant mixture. Refer to «COOLING SYSTEM DRAINING, FILLING AND BLEEDING»(ref-234494-S34432732002006061000000) .

Radiator Leak Test, Removed From the Vehicle

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 the tank.

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