I just replaced the thermostat on my 07 cooper s. There is a bleed screw (I'm guessing) on the top of the thermostat housing. I lost alot of anti freeze becaus I had to replace the faulty water pipe going to the back of the water pump. I started the car up expecting to loose all the anti freeze out of the reservoir to fill this space but haven't lost anything yet. Do I release the bleed screw or remove it and fill it up with a funnel?

 

I figured it out on the bleed screw....you have to loosen the bleed screw on the thermostat housing and loosen the cap on the reservoir and will flow into hoses like it is supposed to keep filling the reservoir until the fluid levels off to full.