Coolant change petrol engine

Accord 03-08 KA20/24

  1. StuH
    Difficulty Level:
    WARNING: We are dealing with the cooling system, the coolant gets VERY hot. Make sure the following procedure is done when the system is cool.

    Although this guide is specific to the 7th Generation petrol accord, the procedure is largely the same for most vehicles.

    10mm Socket (optional, only needed if rmoving the expansion tank)
    Oil pan or similar (min. 6l capacity is advised)
    Clean cloth

    5 litres of Honda coolant

    Step 1 - Start the engine and set temperature control to max or 'HI' on climate control cars. Turn off the engine.
    cool_change (1).

    Step 2 - Locate the drain plug. This is at the bottom of the radiator slightly off-centre. The image below shows the location from above.
    cool_change (2).
    The plug is accessed from below. There's a cut-out in the under tray that is obvious when you get under the font of the car. It is quite easy to feel for the plug.

    Step 3 - Now you have located the drain plug you can proceed to drop the coolant. Remove the radiator cap (no need to do anything with the expansion tank at the moment) and then SLOWLY undo the drain plug ensuring you have something suitable to catch the coolant underneath. Do not remove fully remove the plug, if you do you will have a serious release of coolant on your hands. You can control the flow with the plug and after a few minutes totally remove it. Take time here, the flow slows to trickle but you must let it finish.
    cool_change (3).

    Step 4 - Whilst the coolant is draining you can remove the coolant tank to drain it and give it a clean. The expansion tank is secured by two 10mm bolts (see below), undo these and the tank comes away. Once empty and clean, refit and fill with coolant to the MAX level that can be clearly seen on the tank. I personally didn't fill it at this stage but that's due to using the Lisle funnel and knowing I'd have some left in the funnel that I would use.
    cool_change (5).

    step 5 - Once your coolant has stopped coming out you can remove the container and refit the drain plug. You should have something close to 5l of coolant.
    cool_change (8).

    Step 6 (a) - Time to refill. I am using the Lisle funnel that uses an adapter to secure to the top of the radiator, I'll do a separate step for this funnel. Insert your funnel in the top of the radiator and SLOWLY start to fill the radiator, doing this slowly will help to minimise the amount of air being pulled in. When near the top of the radiator you can start the engine and proceed to add more coolant. As the coolant is circulated around the engine and heater matrix air will (hopefully) be forced out, air trapped in the system is not a good idea and will cause numerous issues. Keep slowly adding coolant up to base of the filler neck. If you are using a normal funnel you can remove it and loosely replace the radiator cap. The car needs to be left to warm up - the workshop manual says this is when the radiator comes on at least twice. Once up to temperature check that the temperature gauge is at the normal operating temperature and you have hot air coming out of the vents. Once happy all is well you can turn the engine off check your levels and top off as necessary. Put the radiator cap on tightly and run the engine again checking for leaks and general performance.

    Step 6 (b) - As mentioned I used the Lisle Spill Free Funnel. Whilst not exactly cheap I'm really impressed. I won't go into the advantages here as @Ichiban has covered it elsewhere. You use the funnel as normal but once the radiator is full you can add more to the funnel and leave the engine running. You will see the air being expelled in the funnel, I didn't get loads but a steady stream of bubbles did pop up. Once your happy you've eliminated all trapped air you can plug the funnel off and use what's remaining to fill the expansion tank.

    cool_change (7). cool_change (10).

    Check that the temperate gauge is staying at the correct level, you have warm air and no other signs of trapped air such as erratic idling. Check the car over the next few days.

    I've no added the workshop manual procedure:

    file-page1. file-page2.
    AndyB1976 likes this.

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  1. wahabishtiaq
    hope won't b much different from diesel...
    1. StuH
      Author's Response
      There's a very good how to on the diesel. The only real difference is you have a bleeder on that needs to be opened.
  2. legend-ary
    Well written and detailed instructions! Good guide