Thank you, I am sure you are right, there are no other bleed screws on the hoses that connect to the heater matrix (near bulkhead) or on the radiator. I have bled the system from the thermostat housing screw and run her up to temperature today. This is after changing the thermostat and the temp sender (green one). All seems ok though I'm a little puzzled at the temperature it seems to sit at. I have run the engine until the thermostat opened but the temperature gauge on the instrument cluster is only reading 70-75. Left it ticking over for 45 mins and it climbed no further. Sat in it revving the engine at about 2k for 5-10 mins but still couldn't get it to hit 80, and when returned to tick over soon dropped back to 70-75. I replaced the temp sensor thinking it might not be giving an accurate reading but the gauge still runs the same, also changed the instrument cluster including the temp gauge to eliminate that. Is this low engine temperature normal for these vans?