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

Cooling System Acura MDX II

Cooling System (mechanical) 22 illustrations ~1990 words

Scheme 1

Scheme 1: Component Location Index
Scheme 1: Component Location Index

Scheme 2

Scheme 2: Radiator Cap Test
Scheme 2: Radiator Cap Test
  1. Remove the radiator cap (A). Wet its seal with engine coolant, then install it on a commercially available pressure tester (B).
  2. Apply a pressure of 93-123 kPa (0.95-1.25 kgf/cm 2 , 14-18 psi).
  3. Check for a drop in pressure.
  4. If the pressure drops, replace the cap.

Scheme 3

Scheme 3: Radiator Test
Scheme 3: Radiator Test
  1. Wait until the engine is cool, then carefully remove the radiator cap, and fill the radiator with engine coolant to the top of the filler neck.
  2. Attach a commercially available pressure tester (A) to the radiator, and apply a pressure of 93-123 kPa (0.95-1.25 kgf/cm 2 , 14-18 psi).
  3. Inspect for engine coolant leaks and a drop in pressure.
  4. Remove the tester, then reinstall the radiator cap.

Scheme 4

Scheme 4: Fan Motor Test
Scheme 4: Fan Motor Test
  1. Disconnect the 2P connectors from the radiator fan motor (A) and condenser fan motor (B).
  2. Test each motor by connecting battery power to No. 2 terminal and ground to No. 1 terminal.
  3. If either motor fails to run or does not run smoothly, replace it (see «RADIATOR AND FAN REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/cooling-system-mechanical/#cooling-system__radiator-and-fan-replacement) ).

Thermostat Test

Replace the thermostat if it is stuck open at room temperature.

To test a closed thermostat

Scheme 5

Scheme 5: Thermostat Test
Scheme 5: Thermostat Test
  1. Suspend the thermostat (A) in a container of water. Do not let the thermometer (B) touch the bottom of the hot container.
  2. Heat the water and check the temperature with a thermometer. Note the temperature when the thermostat first opens, then check the temperature when the thermostat is fully open.
  3. Measure the lift height of the thermostat when it is fully open. Standard Thermostat Lift Height: Above 10.0 mm (0.39 in.) Starts Opening: 169-176°F (76-80°C) Fully Open: 194°F (90°C)

Scheme 6

Scheme 6: Water Pump Inspection
Scheme 6: Water Pump Inspection
  1. Remove the timing belt (see «TIMING BELT REMOVAL»(/acura/mdx/ii-2006-2010/remont/mechanical/#cylinder-head) ).
  2. Turn the water pump pulley counterclockwise, and make sure that it turns freely. If it doesn't, replace the water pump (see «WATER PUMP REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/cooling-system-mechanical/#cooling-system) ). NOTE: When you check the water pump, you may see a small amount of "weeping" from the bleed holes (A). This is normal.
  3. Install the timing belt (see «TIMING BELT INSTALLATION»(/acura/mdx/ii-2006-2010/remont/mechanical/#cylinder-head__timing-belt-installation) ).

Scheme 7

Scheme 7: Water Pump Replacement
Scheme 7: Water Pump Replacement
  1. Drain the engine coolant (see «COOLANT REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/cooling-system-mechanical/#cooling-system) ).
  2. Remove the timing belt (see «TIMING BELT REMOVAL»(/acura/mdx/ii-2006-2010/remont/mechanical/#cylinder-head) ).
  3. Remove the timing belt adjuster (see «TIMING BELT ADJUSTER REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/mechanical/#cylinder-head) ).
  4. Remove the water pump (A) by removing the five bolts.
  5. Inspect and clean the O-ring groove and the mating surface of the engine block.
  6. Install the water pump with a new O-ring (B) in the reverse order of removal.
  7. Clean up any spilled engine coolant.
  8. Install the timing belt adjuster (see «TIMING BELT ADJUSTER REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/mechanical/#cylinder-head) ).
  9. Install the timing belt (see «TIMING BELT INSTALLATION»(/acura/mdx/ii-2006-2010/remont/mechanical/#cylinder-head__timing-belt-installation) ).
  10. Refill the radiator with engine coolant, then bleed the air from the cooling system (see step 10 on «COOLANT REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/cooling-system-mechanical/#cooling-system) ).

Scheme 8

Scheme 8: Coolant Check
Scheme 8: Coolant Check
  1. Look at the coolant level in the coolant reservoir. Make sure it is between the MAX mark (A) and MIN mark (B).
  2. If the coolant level in the coolant reservoir is at or below the MIN mark, add coolant to bring it between the MIN and MAX marks, then inspect the cooling system for leaks.

Scheme 9

Scheme 9: Coolant Replacement
Scheme 9: Coolant Replacement

Scheme 10

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Scheme 13

Scheme 13
Scheme 13
  1. Start the engine. Set the heater temperature control dial to maximum heat, then turn off the ignition switch. Make sure the engine and radiator are cool to the touch.
  2. Remove the radiator cap.
  3. Remove the splash shield (see step 31 on «ENGINE REMOVAL»(/acura/mdx/ii-2006-2010/remont/mechanical/#engine-removal-and-installation) ).
  4. Loosen the drain plug (A) and drain the coolant.
  5. Install a rubber hose (A) on the drain bolt (B) located at the rear of the engine block, then loosen the drain bolt.
  6. When the coolant stops draining, tighten the drain bolt. Remove the rubber hose.
  7. Tighten the radiator drain plug securely.
  8. Install the splash shield (see step 39 on «ENGINE INSTALLATION»(/acura/mdx/ii-2006-2010/remont/mechanical/#engine-removal-and-installation__engine-installation) ).
  9. Remove, drain, and reinstall the coolant reservoir.
  10. Fill the coolant reservoir to the MAX mark (A) with Acura Long Life Antifreeze/Coolant Type 2 (P/N OL999-9011 A). NOTE: Always use Acura Long Life Antifreeze/Coolant Type 2 (P/N OL999-9011 A). Using a non-Acura coolant can result in corrosion, causing the cooling system to malfunction or fail. Acura Long Life Antifreeze/Coolant Type 2 is a mixture of 50% antifreeze and 50% water. Do not add water.
  11. Pour Acura Long Life Antifreeze/Coolant Type 2 into the radiator up to the base of the filler neck. Engine Coolant Capacities (Including the coolant reservoir capacity of 0.7 L (0.19 US gal)): At Coolant Change: 7.3 L (1.93 US gal) After Engine Overhaul: 9.2 L (2.43 US gal)
  12. Start the engine. Hold the engine speed at 1,500 rpm until it warms up (the radiator fan comes on at least twice). Make sure the thermostat is open.
  13. Turn off the engine. Check the level in the radiator, and add Acura Long Life Antifreeze/Coolant Type 2, if needed.
  14. Set the climate control or heater control panel to maximum cool. Start the engine. Hold the engine speed at 1,500 rpm for 5 minutes, then turn off the engine.
  15. Check the level in the radiator, and add Acura Long Life Antifreeze/Coolant Type 2, if needed.
  16. Set the climate control or heater control panel to maximum heat. Start the engine. Hold the engine speed at 1,500 rpm for 5 minutes, then turn off the engine.
  17. Check the level in the radiator, and add Acura Long Life Antifreeze/Coolant Type 2, if needed.
  18. Set the climate control or heater control panel to maximum cool. Start the engine. Hold the engine speed at 1,500 rpm for 3 minutes, then turn off the engine.
  19. Check the level in the radiator, and add Acura Long Life Antifreeze/Coolant Type 2, if needed.
  20. Set the climate control or heater control panel to maximum heat. Start the engine. Hold the engine speed at 1,500 rpm for 3 minutes, then turn off the engine.
  21. Check the level in the radiator, and add Acura Long Life Antifreeze/Coolant Type 2, if needed.
  22. Repeat steps 18 through 21 until the coolant level does not change in the radiator, then install the radiator cap loosely.
  23. Set the climate control or heater control panel to maximum cool. Start the engine. Hold the engine speed at 2,500 rpm for 1 minute.
  24. Set the climate control or heater control panel to maximum heat, and select high speed heat mode on the rear control panel. Measure the temperature of the air from the rear floor vent for 2 or 3 minutes. Make sure the temperature is above the standard line of the graph as shown. If the temperature is below the standard line, repeat steps 18 through 21 several more times. Then loosely install the radiator cap and recheck.
  25. With the engine idling, make sure you do not hear the sound of water flowing near the rear heater unit. If you hear water flowing, repeat steps 18 through 21 several more times.
  26. Install the radiator cap fully.
  27. Fill the coolant reservoir with Acura Long Life Antifreeze/Coolant Type 2 up to the MAX mark on the coolant reservoir, then add an extra 0.4 L (0.11 US gal) coolant.
  28. Clean up any spilled engine coolant.
  29. If the maintenance minder required to replace the engine coolant, reset the maintenance minder (see «RESETTING THE MAINTENANCE INFORMATION DISPLAY»(/acura/mdx/ii-2006-2010/remont/reset-procedures/#maintenance) ), and this procedure is complete. If the maintenance minder did not require to replace the engine coolant, go to step 30.
  30. Connect the Honda Diagnostic System (HDS) to the data link connector (DLC) (see step 2 on «HOW TO USE THE HDS (HONDA DIAGNOSTIC SYSTEM)»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#fuel-and-emissions-systems__how-to-use-the-hds-honda) ).
  31. Turn the ignition switch ON (II).
  32. Make sure the HDS communicates with the vehicle and the powertrain control module (PCM). If it doesn't communicate, troubleshoot the DLC circuit (see «DLC CIRCUIT TROUBLESHOOTING»(/acura/mdx/ii-2006-2010/remont/testing-diagnostics/#pgm-fi-system__dlc-circuit-troubleshooting) ).
  33. Select BODY ELECTRICAL with the HDS.
  34. Select ADJUSTMENT in the GAUGES MENU with the HDS.
  35. Select RESET in the MAINTENANCE MINDER with the HDS.
  36. Select MAINTENANCE SUB ITEM 5 RESET with the HDS.
  37. Turn off the engine. Check the level in the radiator, and add Acura Long Life Antifreeze/Coolant Type 2, if needed. NOTE: Removing the radiator cap while the engine is hot can cause the coolant to spray out. Always let the engine and radiator cool before removing the cap.

Scheme 14

Scheme 14: Thermostat Replacement
Scheme 14: Thermostat Replacement
  1. Do the battery terminal disconnection procedure(See «DISCONNECTION»(/acura/mdx/ii-2006-2010/remont/body-electrical/#battery__disconnection) . Remove the battery (See «REMOVAL»(/acura/mdx/ii-2006-2010/remont/body-electrical/#battery__removal) .
  2. Remove the air intake duct (see step 8 on «REMOVAL»(/acura/mdx/ii-2006-2010/remont/mechanical/#engine-removal-and-installation) ).
  3. Drain the engine coolant (see «COOLANT CHECK»(/acura/mdx/ii-2006-2010/remont/cooling-system-mechanical/#cooling-system) ).
  4. Remove the thermostat cover, then remove the thermostat.
  5. Install the new thermostat with a new rubber seal and with the pin on the top side.
  6. Install the battery(See «INSTALLATION»(/acura/mdx/ii-2006-2010/remont/body-electrical/#battery) . Do the battery terminal reconnection procedure(See «RECONNECTION»(/acura/mdx/ii-2006-2010/remont/body-electrical/#battery__reconnection) .
  7. Refill the radiator with engine coolant, then bleed air from the cooling system (see step 10 on «COOLANT REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/cooling-system-mechanical/#cooling-system) ).
  8. Clean up any spilled engine coolant.

Scheme 15

Scheme 15: Water Passage Replacement
Scheme 15: Water Passage Replacement
  1. Do the battery terminal disconnection procedure(See «DISCONNECTION»(/acura/mdx/ii-2006-2010/remont/body-electrical/#battery__disconnection) . Remove the battery (See «REMOVAL»(/acura/mdx/ii-2006-2010/remont/body-electrical/#battery__removal) .
  2. Remove the air intake duct (see step 8 on «ENGINE REMOVAL»(/acura/mdx/ii-2006-2010/remont/mechanical/#engine-removal-and-installation) ).
  3. Drain the engine coolant (see «COOLANT CHECK»(/acura/mdx/ii-2006-2010/remont/cooling-system-mechanical/#cooling-system) ).
  4. Remove the upper radiator hose, lower radiator hose, heater hoses, and water bypass hoses from the water passage. Disconnect the engine coolant temperature (ECT) sensor 1 connector and the exhaust gas recirculation (EGR) valve connector.
  5. Remove the water passage.
  6. Install the water passage in the reverse order of removal.
  7. Install the battery(See «INSTALLATION»(/acura/mdx/ii-2006-2010/remont/body-electrical/#battery) ).Do the battery terminal reconnection procedure(See «RECONNECTION»(/acura/mdx/ii-2006-2010/remont/body-electrical/#battery__reconnection) .
  8. Refill the radiator with engine coolant, then bleed air from the cooling system (see step 10 on «COOLANT REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/cooling-system-mechanical/#cooling-system) ).
  9. Clean up any spilled engine coolant.

Radiator and Fan Replacement

Note. Use fender covers to avoid damaging painted surfaces. To avoid damaging the wire and terminals, unplug the wiring connectors carefully while holding the connector portion. Mark all wiring and hoses to avoid misconnection. Also, be sure that they do not contact any other wiring or hoses, or interfere with any other parts.

Scheme 16

Scheme 16: Radiator and Fan Replacement
Scheme 16: Radiator and Fan Replacement

Scheme 17

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Scheme 22
Scheme 22
  1. Do the battery terminal disconnection procedure(See «DISCONNECTION»(/acura/mdx/ii-2006-2010/remont/body-electrical/#battery__disconnection) .
  2. Remove the battery (See «REMOVAL»(/acura/mdx/ii-2006-2010/remont/body-electrical/#battery__removal) and battery base (see step 11 on «ENGINE REMOVAL»(/acura/mdx/ii-2006-2010/remont/mechanical/#engine-removal-and-installation) ).
  3. Remove the air cleaner assembly (see «AIR CLEANER ELEMENT INSPECTION/ REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/mechanical/#intake-air-system) ).
  4. Remove the front grille cover, then remove the front grille.
  5. Disconnect the fan motor connectors (A), harness clamp (B), engine coolant temperature (ECT) sensor 2 subharness connector (C) and coolant reservoir hose (D).
  6. Drain the engine coolant (see «COOLANT CHECK»(/acura/mdx/ii-2006-2010/remont/cooling-system-mechanical/#cooling-system) ).
  7. Remove the upper radiator hose.
  8. Unclamp the hose clamps (A) and remove the ATF cooler hoses (B), then plug the line and hoses.
  9. Remove the ATF cooler pipe mount bolts (C), then remove the ATF cooler pipe (D).
  10. Remove the lower radiator hose (A) and disconnect the ECT sensor 2 connector (B) and loosen the two bolts (C).
  11. Disconnect the hood latch switch connector (A), clamps (B), then remove the hood latch (C).
  12. Remove the bulkhead bracket (D), and radiator and A/C condenser mount upper bracket/cushion (E), then remove the fan shroud mount bolts (F).
  13. Move the fan shroud assemblies toward the engine, then pull up the radiator assembly (A).
  14. Remove the fan shroud assemblies.
  15. Install the radiator and fans in the reverse order of removal.
  16. Install the bulkhead bracket in the reverse order of removal. Apply body paint to the bulkhead bracket mounting bolts.
  17. Set the upper and lower cushions securely.
  18. Fill the transmission with ATF (see «ATF REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/automatic-trans/#automatic-transmission) ).
  19. Install the battery(See «INSTALLATION»(/acura/mdx/ii-2006-2010/remont/body-electrical/#battery) .Do the battery terminal reconnection procedure(See «RECONNECTION»(/acura/mdx/ii-2006-2010/remont/body-electrical/#battery__reconnection) .
  20. Fill the radiator with engine coolant and bleed the air from the system (see step 10 on «COOLANT REPLACEMENT»(/acura/mdx/ii-2006-2010/remont/cooling-system-mechanical/#cooling-system) ).
  21. Adjust the engine hood latch (see «HOOD ADJUSTMENT»(/acura/mdx/ii-2006-2010/remont/exterior-body-panels/#hood) ).