Hi,

below the colling radiator is a valve. The workshop manual says you should open it to flush the cooling system (i want to replace the water pump).

Is there a trick to open it? I didn't want to break it - really tried hard, but it won't open.

Thanks

 

No, no trick. It must just be stuck.
I drained mine about 3 years back and had no problem opening it, just used a large screwdriver like you did ( from the picture ).
It was normal right hand thread as I recall, but my recall ain't what it used to be.

 

When you take off the water pump and lower radiator hose, it will drain.
Changed my water pump in parking lot last night after work.

 

You are correct, just did mine a couple of months ago, righty tighty lefty Loosey.