Apart from flushing the system, how do you know when you've got an air blockage and how do you go about clearing it?
Park nose up
Get domestic radiator bleed valves to fit into thermostat housing and radiator filler points.
Fill expansion tank to level. Fill it slowly so water has time to filter down into system.
Fit cap on to expansion tank
Remove radiator filler point and fill till it overflows do it slowly so water has time to filter down into system.
When full, Fit domestic radiator bleed valve to radiator filler point.
Remove thermostat housing filler point and slowly fill it till it overflows. Gently squeeze top radiator hose to expel air and repeat until it is overflowing and no air can be removed.
Fit domestic radiator bleed valve to thermostat housing filler point.
Fill expansion tank to above filler mark.
Run engine till warm.
whilst engine is running, bleed thermostat housing and radiator filler points using radiator bleed valves,
Engine heater must be set to hot in all positions.
Expansion tank must have cap fitted.