Honda Prelude Accord Civic S2000 2001-2006

Thermostat

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Removal & Installation



Accord & Prelude
2001-02 Models

CAUTION
Never open, service or drain the radiator or cooling system when hot; serious burns can occur from the steam and hot coolant. Also, when draining engine coolant, keep in mind that cats and dogs are attracted to ethylene glycol antifreeze and could drink any that is left in an uncovered container or in puddles on the ground. This will prove fatal in sufficient quantities. Always drain coolant into a sealable container. Coolant should be reused unless it is contaminated or is several years old.

  1. Note the radio security code and station presets.
  2.  
  3. Disconnect the negative battery cable.
  4.  
  5. Drain the engine coolant into a sealable container, to a level below the thermostat.
  6.  
  7. Use a pair of pliers to release the tension from the hose clamp, then disconnect the hose from the thermostat housing.
  8.  
  9. Remove the fasteners from the thermostat housing, remove the housing, then remove the thermostat.
  10.  

To install:

  1. Install the thermostat using a new seal. If the thermostat has a small bleed hole, make sure the bleed hole is on the top.
  2.  
  3. Apply an anti-seize compound to the threads of the fasteners.
  4.  
  5. Position the thermostat housing and secure with the retaining bolts.
  6.  
  7. Attach the hose to the housing and secure with the hose clamp
  8.  
  9. Set the heater to the full hot position.
  10.  
  11. On the 2.2L and 2.3L engines, locate the coolant bleed valve near the thermostat housing and open the valve 1 / 2 turn.
    NOTE
    When mixing a 50/50 solution of antifreeze and water, using distilled water may help to keep the cooling system from building up mineral deposits and internal blockage.



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    Fig. After loosening the hose clamp, disconnect the hose from the thermostat housing



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    Fig. Unthread the bolts from the thermostat housing



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    Fig. Once all the bolts have been removed, pull the thermostat housing away from the engine



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    Fig. Installed view of the thermostat and gasket as it sits in the housing



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    Fig. Remove the thermostat by pulling it straight out from the housing



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    Fig. Remove the gasket from the thermostat and replace, if necessary



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    Fig. View of the thermostat and gasket



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    Fig. The thermostat housing on most models has two notches cut into it to ensure the correct installation of the thermostat



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    Fig. During installation, always position the air bleed at the top of the thermostat

  12.  
  13. Top off the cooling system and overflow reservoir with a 50/50 mixture of a recommended antifreeze and water solution and bleed the system to remove any air pockets as necessary. Simultaneously squeeze the upper and lower radiator hoses to help push any captured air pockets out of the system.
    WARNING
    The manufacturer does not recommend using a coolant concentration of greater than 60% antifreeze.

  14.  
  15. Inspect all coolant hoses and fittings to make sure they are properly installed and if previously opened, close the bleed valve.
  16.  
  17. Connect the negative battery cable.
  18.  
  19. Install the radiator cap loosely and start the engine. Allow the engine to run until the cooling fan has cycled two times, then turn the engine off and top off the cooling system as necessary.
  20.  
  21. Install the radiator cap and inspect for leaks.
  22.  
  23. Enter the radio security code.
  24.  

2003-06 2.4L Engine
  1. Drain the engine coolant.
  2.  
  3. Clean any dirt off the quick connector (A), thermostat cover, and lower radiator hose.
  4.  
  5. Pull out lock (B) by hand, then wiggle the quick connector loose, and remove it from the thermostat cover. Do not use any tools to remove the quick connector.

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    Fig. Clean the dirt off of the quick connector (A), then pull out lock (B) by hand, then wiggle the quick connector loose, and remove it from the thermostat cover

  6.  
  7. Remove the thermostat (A).
  8.  

To install:

  1. Install the thermostat with a new O-ring (B).

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    Fig. Always use a new O-ring (B) when installing the thermostat (A)

  2.  
  3. Check the quick connector (A) and set ring (B) for cracks or damage. If the connector and/or set ring are cracked or damaged, replace the connector.
  4.  
  5. Make sure the set ring is in place inside the quick connector. If the set ring is off the connector, replace the quick connector.
  6.  
  7. Replace the O-ring (C) in the quick connector.
  8.  
  9. Check the lock (D). If the lock is damaged or deformed, replace it. When installing the new lock on the connector, press it straight down along the groove.
  10.  
  11. Clean the connecting surface of the thermostat cover (E), then apply clean engine coolant around the connecting surface.

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    Fig. Thermostat installation

  12.  
  13. Push down the lock, then push the quick connector onto the thermostat cover until you hear it click.
  14.  
  15. Refill the radiator with engine coolant, and bleed air from the cooling system with the heater valve open.
  16.  

2003-06 3.0L Engine
  1. Make sure you have the anti-theft codes for the audio unit (and navigation code if equipped), then write down the audio presets. Make sure the ignition switch is OFF.
  2.  
  3. Disconnect the negative cable from the battery first, then the positive cable, then remove the battery.
  4.  
  5. Drain the engine coolant.
  6.  
  7. Remove the ground cable and thermostat cover, then remove the thermostat.

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    Fig. Exploded view of the thermostat-3.0L engine shown

  8.  

To install:

  1. Install the thermostat with new rubber seal.
  2.  
  3. Install the battery. Clean the battery posts and cable terminals with sandpaper, then assemble them and apply grease to prevent corrosion.
  4.  
  5. Refill the radiator with engine coolant, then bleed air from the cooling system.
  6.  
  7. Clean up any spilled engine coolant.
  8.  
  9. Enter the anti-theft codes for the audio unit (and navigation code if equipped), then enter the audio presets.
  10.  
  11. Set the clock.
  12.  

Civic
1.7L And 1.8L Engines
  1. Drain the engine coolant.
  2.  
  3. Remove the harness clamp bracket and thermostat cover, then remove the thermostat.
  4.  
  5. Install the thermostat with a new rubber seal.
  6.  
  7. Refill the radiator with engine coolant, then bleed air from the cooling system.
  8.  
  9. Clean up any spilled engine coolant.

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    Fig. Exploded view of the thermostat-1.7L engine



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    Fig. Exploded view of the thermostat-1.8L engine

  10.  

2.0L Engine
  1. Drain the engine coolant.
  2.  
  3. Remove the splash shield.
  4.  
  5. Remove the lower hose, then remove the thermostat.

    Click image to see an enlarged view

    Fig. Exploded view of the thermostat-2.0L engine

  6.  

To install:

  1. Install the thermostat with a new O-ring, then install the lower hose.
  2.  
  3. Install the splash shield.
  4.  
  5. Refill the radiator with engine coolant, and bleed the air from the cooling system with the heater valve open.
  6.  

S2000
  1. Drain the engine coolant.
  2.  
  3. Remove the lower radiator hose and the thermostat cover, then remove the thermostat.

    Click image to see an enlarged view

    Fig. Exploded view of the thermostat-S2000

  4.  

To install:

  1. Install the thermostat with a new rubber seal.
  2.  
  3. Install the thermostat cover and the lower radiator hose.
  4.  
  5. Refill the radiator with engine coolant, then bleed air from the cooling system.
  6.  
  7. Clean up any spilled engine coolant.
  8.  

 
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