Changing engine coolant

Recommended engine coolant fluid

See: Engine coolant fluid recommendations

Normal operating temperatures

According to the workshop manual the operating temperature is when the radiator fans are running. This happens at 91C-95C (196F-203F).

Real life results show that in normal weather conditions the engine coolant temperature operates between 82C-90C (180F-194F).

At 78C (172F) the thermostat will start to open and will be fully opened at 90C (194F).

Required tools and fluids

• LHD: 6,5L / 6,87qts engine coolant fluid (or a little more if you would like to "flush" the engine)
• RHD: 6,4L / 6,77qts engine coolant fluid (or a little more if you would like to "flush" the engine)
• 12mm wrench
• Oil/Fluid catch pan
• Floor jack + 2 jack stands
• Kapton tape
• Cable ties
• Clear plastic hose (optional)

How to change the engine coolant fluid

Pre-conditions and jacking up the car

• Make sure that the engine is cold. Never open the cooling system when the engine is hot.
• Put the car in the first gear and set the parking brake.
• Turn on the ignition and set the temperature of the A/C to maximum heat. Make sure the A/C button is off (green LED not active).
• Wait 10 seconds and then turn off the ignition.
• Jack up the car on the front by using the central jacking point near the engine.
• There are two front-jacking-points on each side. Place one jack stand on each side at the jacking-point that is the furthest away from the front wheel.
• Lower and remove your floor jack (or keep it in place for extra safety)
• You want to make sure that the front of your S2000 is elevated.

Draining the engine coolant fluid

• The white colored engine coolant fluid draining bolt is located at the bottom left side of the radiator.
• Place your oil catch pan below the engine oil drain bolt.
• Remove the radiator cap on the top of the radiator. The engine has to be cold!
• Slightly screw open the bleeding valve near the throttle body.
• Remove the rubber cap from the bleeding port near the firewall (only applicable to LHD models).
• Remove the engine coolant fluid drain bolt.
• The old engine oil will now drain from the oil pan and you might need to re-adjust your oil catch pan.
• Draining the radiator completely can take up to 2 hours.
• In the meantime unscrew and remove the cap of the coolant overflow reservoir
• Remove the coolant overflow reservoir by simply pulling it upwards.
• Empty the reservoir and clean/flush it with water. Use tap water, not distilled water (Distilled water
• If possible: Once no more fluid is coming out of the radiator, lower the front of you car and elevate the back of your car. When no more fluid is draining out of the radiator, lower the back of your car and elevate the front again.
• At this point there will still be engine coolant fluid inside your engine and some hoses.
• If you want to get it out you will need to remove the thermostat. See "tbc".
• Now only very little engine coolant fluid is left in your system.
• If you also want to get the last bit out of your system you can use compressed air to push it out of the engine and hoses.

• Once all the fluid has been drained I like to fill fresh engine coolant fluid into the radiator to "rinse or flush" it.
• Wait until no engine coolant fluid (either old or new from "rinsing") comes out of the radiator.

Adding new engine coolant fluid

• Make sure your thermostat and all hoses are connected again.
• The bleeding valve on the throttle body and on the draining port on the firewall should still be opened.
• Hand tighten the engine coolant fluid draining bolt on the bottom left side of the radiator.