Hi all, I have a 83 Mk1 Golf that has had a Passat VR6 engine conversion. All is coming along ok, apart from i'm now stuck on what to do regarding the coolant system. I believe the heating systems differ between the Mk1 and the Mk2/Mk3 in that the coolant is always flowing around the system with the later cars, but a flap within the airbox diverts the hotter coolant past the matrix. On the Mk1 there is an inline valve in the cylinder head hose that is controlled to allow coolant through the matrix or not. At present the previous owner has bypassed the MK1 heater matrix unit and joined the t