Honda Accord (CG, 1998-2002) 4-Cylinder Coolant Flush, Refill and Bleed

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Time 1.5-2 hours

Level Easy

Steps 11

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Caution

Never open the radiator cap or bleeder on a hot, pressurised system except with extreme care; hot coolant causes serious burns.
Use jack stands when the front is raised.
Coolant is poisonous to pets and children; dispose of old coolant and flush water properly.

Introduction

This guide covers draining, flushing and refilling the cooling system on the 1998-2002 Accord four-cylinder, with the air bleed at the bleeder bolt in the thermostat housing area. The radiator drain is the white plastic plug at the bottom of the radiator. For a thorough flush, the original writeup removes the lower radiator hose and thermostat housing and runs water through the engine until it comes out clear, then refits the thermostat and fills with Honda Type II coolant. A second 6thGenAccord.com thread (https://www.6thgenaccord.com/forums/posts/806716/) identifies the four-cylinder bleeder bolt from the parts diagram and recommends raising the front of the car while bleeding to help air escape. Adapted from a community writeup by BlkCurrantKord on 6thGenAccord.com (https://www.6thgenaccord.com/forums/threads/coolant-flush-diy.1959/).

Procedure

11 steps

Step 1: Start cold, heater on hot

Work on a cold engine. Set the heater temperature control to full hot so coolant can flow through the heater core.
Step 2: Drain the radiator

Place a drain pan under the radiator and open the white drain plug at the bottom of the radiator. Remove the radiator cap to help it drain. Empty the coolant reservoir as well.
Step 3: Remove the lower hose and thermostat housing

For a full flush, remove the lower radiator hose to let more coolant out. Remove the thermostat housing, take the thermostat out, and refit the housing without the thermostat so water can pass freely through the engine.
Step 4: Flush with water

Reconnect the lower hose and close the drain plug. Disconnect the upper radiator hose and run water from a garden hose into the radiator's upper inlet until it comes out clear at the upper hose. Another member's alternative is to fill with distilled water, run the engine with the heater on hot, then drain and repeat until the water comes out clear. If you use that method, let the engine cool before each drain, because the water will be hot.
Step 5: Refit the thermostat

Drain the flush water, then reinstall the thermostat in its housing, with a new gasket or O-ring if needed, and reconnect all hoses and clamps.
Step 6: Fill slowly

With the heater still set to hot, slowly fill the radiator with Honda Type II coolant to the filler neck, and fill the reservoir to the cold mark.
Step 7: Open the bleeder bolt

Open the bleeder bolt until coolant flows out in a steady stream without air, then close it. The thread identifies it from the 4-cylinder parts diagram and says it lets trapped air out of the thermostat-housing area; check your service manual if you cannot find it.
Step 8: Raise the front and run the engine

Set the parking brake and chock the rear wheels. Raising the front on jack stands helps air rise to the radiator neck and the bleeder. With the radiator cap off, start the engine in a ventilated area and let it idle with the heater on full hot until the thermostat opens and the upper radiator hose gets hot.
Step 9: Purge air

Squeeze the upper radiator hose to push air out and top up the radiator as the level drops. The second thread describes cracking the bleeder briefly once warm to release trapped air; take great care, as the coolant will be hot.
Step 10: Cool and top off

Shut the engine off and let it cool. Top off the radiator to the neck, refit the cap, and set the reservoir to its cold mark.
Step 11: Final check

Run the engine at full heat with the fan on until it reaches normal temperature, confirm the heater blows hot and check for leaks. Recheck the level after the next cool-down.