TaDa said:

Anyway, I topped up the coolant last weekend (took the bleeder screw out, raised the header tank until coolant came out of the bleed hole, replaced screw, replaced header tank and then topped up)

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TaDa said:

Sure. You ned to raise the header tank to ensure the coolant level in the header tank is higher than the rest of the system. This helps push out air that might otherwise be left trapped in the system.
Take the bleed screw out, lift the header until you see water about to come out, replace the screw. You might find an extra set of hands makes this easy the first time. If you need to do this once, don't be too surprised if you need to do this again after a few miles as other air locks might be freed by the engine being run.

Have fun

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