86-89 Accord Thermostat

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In this page we will illustrate how to replace the thermostat on 1986-1989 Honda Accord equipped with 2.0 L Engine.

In the vehicle we are working on the thermostat was stuck on the open position, causing the engine coolant to remain below operating temperature and for the same reason the Engine control computer was operating in open loop mode.







 The first step is to locate the radiator drain plug and drain the coolant in to a clean container, you may need to drive your vehicle up on ramps to gain access to the radiator drain plug ( located at bottom of radiator ).

Next, disconnect the negative battery cable for safety, remove the air intake hose to gain access to the thermostat housing, this particular vehicle had an aftermarket cold air intake system installed ( see image ).

Using channel lock pliers slide the hose clamp away from the thermostat housing and disconnect the upper radiator hose from the housing.

Press the plastic tab located on the side of the electrical connector and unplug the coolant temperature sensor as shown on the image.

Remove the bolt that fastens the ground wire to the water outlet and move the wire out of the way.

Remove the two bolts that hold the water outlet in place  and remove it from the vehicle.

Using needle nose pliers, pull the thermostat out.

Scrape any old gasket material from the water outlet and thermostat housing using a flat scraper.

Make sure that you install the new seal on the thermostat correctly ( see image ) the air bleed needs to be at the top in between the two rubber dots on the seal.

Install the new thermostat with the spring facing the engine, install the water outlet and the radiator hose back on, install the ground wire  and plug the connector on the coolant temp sensor back on, tighten the radiator drain plug and fill the radiator with coolant, don't install the air intake hose yet, you will need to gain access to the bleeder screw, install the negative battery cable back on and start the engine.

Using a 12mm box end wrench, crack the bleeder screw located on the thermostat housing open as shown on the image to bleed the air out of the cooling system, ( this is done with the engine running, make sure that you keep your hands away from all moving parts ). If engine coolant starts coming out you will need to close the bleeder screw.

At the same time, keep an eye on the temperature gauge, if the engine temperature goes past 200 degrees F, turn the engine off and allow it to cool down, once it has cooled down open the radiator cap and add coolant if needed, start the engine again and repeat the steps described earlier,   once the thermostat opens the engine coolant will circulate through the radiator and the engine temperature will remain at a constant 195 degrees F.

Inspect for leaks, make sure that the bleeder screw is tight and install the air intake hose back on the engine, take the car for a test drive, at your return inspect for leaks again, if you don't see any and the thermostat works properly you are done.