Today at Atelier Kaz - ex-Honda R&D, F1, Indy/CART engineer

The MIN line is just above the air separator of the water passage and while the air can enter from the top small coolant hose,
any air left in the separator chamber would be easily pushed out towards the tank once the engine started but
you want to prevent the air being introduced during this process.

Close the bleeder plug, top up the tank to the filler neck or add enough coolant in the funnel.

Move on to the radiator bleeder plug.

Open the radiator bleeder plug slightly.

Keep eye on the tank level as the air escapes from the bleeder plug.

Wiggle the plug.

You will start hearing the bubbling sound and once no more bubbles with steady seepage of the coolant, close the plug.






Top up the tank/funnel again and attach the clear tube to the heater core bleeder plug if you have later spec aluminium L-shaped pipe with the bleeder plug.

If you have very early model, it would be a rubber cap instead so you are very likely to revisit here later.

This is the most important area of the entire bleeding process because it takes ages for any air trapped inside the heater core.

Follow the same process as per the thermostat cover bleeder.

Collect at least 1.0 - 1.5L of coolant through this specific bleeder.

With the early model rubber cap, you could use larger ID clear tube just for this process but if you don’t have one,
revisit this bleeder few times after each driving session. Will touch on this later.


Top up the tank/funnel and repeat the same process at the bleeder on the heater return pipe (eng bay firewall).

Top up the tank/funnel and repeat the same process one more time at the thermostat cover bleeder but on this occasion,
collect enough coolant so that the coolant level sits just above the MAX line.


Up to this point, you should have managed to remove majority of the air inside the system.

Double check that the bleeder plugs are all closed (and the rubber cap + clamp for the early model).

Close the tank cap to the 1st notch (not fully closed).

Start the engine and keep eye on the coolant level as well as the temperature gauge.

The coolant enters the radiator from the bottom side.

Until the thermostat starts opening, the lower rad hose or the rad body itself would be cold.

Once the thermostat starts opening, you can start feeling the rad body getting warmer.

At this point, you could squash the big coolant hose at the thermostat cover.

You may be able to hear the float/jiggle pin of the thermostat moving back and forth while any remaining air pushed back to the tank.

Keep eye on the temperature gauge and the coolant level.

Wait for the rad fan to kick in.

Depending on the air temperature, it can take more than 20min after starting the engine so be patient.

If followed the above entire procedure, never experienced but if the needle gets even slightly above the normal level or
the coolant level getting close to the neck, stop the engine even before the rad fan kicks in.


From what I heard, this situation can happen on the early model with the rubber cap at the heater core bleeder.


No damages done but you didn’t bleed the system enough.


Too much air still left in the system so you want to bleed the air further ONCE the engine has cooled down.


If you didn't experience the higher temperature situation or the potential overflow from the tank,
let the engine run for several minutes after the rad fan kicked in and then stop the engine.

Park the car overnight and check the coolant level.

Top up the coolant if required to set the coolant level at MAX line.