How to replace the spark plugs on a Mercedes C-Class W203

In this video we can see how to change the spark plugs on a Mercedes C-Class W203: we need to work on the cold engine, to avoid burns and to have a proper adjustment; disconnect the negative pole and clean the area around the engine cover; remove the cover and with the 8 socket wrench remove the ignition coil for each spark plug.

Number them, if we remove them all together.

This way we will be sure to put them back in the right place. Before unscrewing the spark plugs, use compressed air or a cloth to carefully clean the dirt around the spark plug: if even a single grain of dust falls into the combustion chamber it can cause serious damage to the engine.

Unscrew the spark plug with a 16 mm socket wrench and pull it out carefully to prevent it from falling. Apply a very small amount of high temperature anti-seize grease only on the threads of the new spark plug, which we will screw in by hand and then tighten to 28 Nm. Reassemble the coil with a light brush of dielectric grease inside the rubber terminal (prevents corrosion).

The coil should be pushed into its socket until you hear a "click", indicating that it is properly hooked; tighten the fixing screw to 9 Nm and repeat for all the others. Reassemble the engine cover and reconnect the battery.