I'm pretty sure it's not a bleeding problem, as the gurgles are only there for a little while after a cold start, when the car has been standing for several hours or a day. After I start the car, with the heater on, I can hear bubbles rushing through the heater (driver's=lefthand footwell) when I rev the engine. With heating off, no noise. It seems that air has collected somewhere in the engine, which is then forced through the heater on its way to the expansion tank. After that, no more noises. On a hot start, no noises. Also, after I fitted new hoses and put new coolant in, I could hear some air as the last bubbles of air in the system were flushed out, but after that I heard nothing for several weeks. Now it's back!?
Now that I think about it, the car did this when I bought it some 70k km ago, and the dealer I got it from solved the problem under warranty (pity they didn't fix the missing (!) airco at the same time, but that's another story). There's no noticable loss of coolant, the oil is clean, so I'm baffled. The only thing I can think of is the waterpump seal. Perhaps some air is pulled past the seal as the engine cools down? Maybe I'll take off the timing cover and have a look for stains there.
Any ideas? From previous threads I got the impression that waterpumps are rarely a problem on these engines. Then again, it's done 170k km (105k miles) of proper wink driving.