E30 Zone

So my 325i started pressurising the coolant system, no oil in the water or vice versa and the sniff test showed no exhaust gasses. I've had a new head gasket fitted and just ran the car about 8 miles and it started overheating. I loosened the filler cap and it was pressurised again but the coolant that came out was stone cold...
Any ideas. Cracked head or block? or just needs bleeding correctly......there's hoping!!
Thanks, Matt

Air lock.

Follow the full bleeding procedure.

Ben