F355 Coolant Change Procedure
Disclaimer: Perform these procedures at your own risk. I am not responsible for any inaccuracies or damages which may incur. This article assumes you have some mechanical knowledge and understand how to properly lift the car and use jack stands.
STEP1: Although the fill cap is vented to the air I opened it anyway to relieve any pressure.
STEP2: With a large flathead screwdriver remove the drain plug located on the bottom of the radiators on each side. Make sure the rubber o-ring comes off with it. The old plugs and o-rings looked fine, but I replaced them anyway with OEM parts from the dealer anyway. Make sure you use a large container to catch the fluid then screw the plug and o-ring back on.
STEP3: Pull both engine freeze plugs using a 6mm hex key. They are located under the header on each bank of the engine. Don’t remove the freeze plugs completely or you will make a huge mess. Loosen them enough for the fluid to start draining and come back later and remove it all the way when all the fluid looks drained. Replace both plugs after the fluid stops draining.
This happened when I immediately removed the freeze plugs.
STEP4: Pour the coolant into the tank until the level is a couple of centimeters below the filler hole. Do not replace the pressure cap. Start the engine, turn on the heater to MAX temp, fan speed 2 & STOP button out. Watch the coolant level in the expansion tank carefully, as the engine starts to warm & the thermostat starts to crack open the level will drop. Keep adding coolant up to the final level only until the level stops going down.
Once the radiator fans start to come on you know the engine is good & hot. Shut the engine down & allow to cool. When the engine is cold check & top-up the level and replace pressure cap. Once you've driven the car for 1/2 hour or so re-check the levels.
If necessary you can bleed the system from the bleed screw which is directly on top of the thermostat housing (underneath the PAS reservoir).