I think you should persevere. When my Bis engine was repaired following the timing chain breaking, I also had the gurgling noises. I got a bit concerned by it, however the car drove fine. The following day the coolant light on the dash lit up, so filled it up with a coolant mix. I opened up the bleed at the front slightly, to allow air to escape. In the next couple of days, I simply filled up with coolant mix when indicator lits up. When the gurgling stopped, tightened the bleed screw. it drives great.