Transformer arrives in Colchester

[Lancialulu]

Slowly getting the beast back to life.

Cambelt change, waterpump change, injectors stripped and rebuilt by local expert and tested (4 out of 6 fully gummed up to start with), service alternator as it requires the fuel tank out .....

Now I need some help. The pic is of the rear bank of the 164 V6 3.0 12v. What does the chrome ball vavlve do. I assume it should either be a blanking plug or some sort of cooling system pipe????

Any advice??