Malcolm Stebbins wrote:
> Is the BOLT that is used to bleed the front radiator any special bolt?
>
> Does it have grooves in the threads to let the air escape?

The "Original" bolt does have a groove on one side that goes nearly to
the bolt head.  That way, just loosening the bolt provides an airway.
It is made of brass.

If an ordinary M8 bolt is used, then it must be completely removed to
bleed the radiator.

Mike