A quick tutorial on how to do an engine coolant change on a W203 C200 Mercedes Benz.

Difficulty Rating


Tools/Parts Required

  • Replacement Coolant (Premixed or concentrate + demineralised water)
  • A drain pan to collect old coolant
  • 8mm socket wrench

Step 1

Ensure the engine is cold, unscrew the coolant reservoir cap and put it to the side.

WARNING: Never open a coolant reservoir while the engine is hot, there is a high risk of steam burns

Step 2

Remove the plastic splash guard underneath the front of the car (6x 8mm bolts).

Locate the red coolant drain screw beneath the car. On RHD cars it will be located on the inner passengers side just behind the front bumper.

Step 3

Place a tub or pan below the screw and loosen the drain screw off, if the screw won’t budge carefully use a flat head screwdriver to loosen. Keep the screw open until coolant stops flowing, this may take some time.

Once flow has ceased, tighten the screw.


Step 4

Prepare the coolant by mixing demineralised water with coolant concentrate to a 50:50 ratio – do NOT use tap water for mixing. Alternatively premixed coolant can be used.

Fill the coolant reservoir with the coolant mixture up to the black line on the reservoir, place the coolant cap back on the reservoir.

Step 5

Turn on the engine and let the car idle for 10 minutes with the heater maxed out to fully bleed the system.

Check the coolant level in the reservoir, if the coolant requires topping up wait until the car has cooled down before opening the reservoir. Once topped up, reinstall the splash guard beneath the car.

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