s210 e300td 1998 gurgling noises at switch off

[Triv]

Hi all, I'm a new member and new to Mercedes-Benz ownership, having been a Volvo man for most of my life but never again after a v70!
The Merc is fantastic. The interior like new, mechanicals well looked after and the bodyshell like lacework. I have never owned such a rusty car!
Before I get stuck in, doing the bits and pieces I'd like to, I have a question regarding the (I guess) cooling system. On switch off, I can hear a gurgling noise that goes on for between 1 and 2 minutes. It sounds like something draining away behind the centre console. Does anyone have any experience of this or a hypothesis as to what it could be?
Thanking you in advance.
Triv

 

[GordonTarling]

Could be an airlock somewhere in the heating system, or there are some models which have a coolant pump that runs for a while after shut down - don't know if yours has got this or not.

 

[Dieselman]

It has a coolant circulation pump, but no over-run on switch off.

Try bleeding the system by allowing it to idle with the header tank cap off for a while, however, gurgling normally indicates head gasket problems.
Look for bubbles in the header tank.

 

[Triv]

Ok, I've had a chance to play with it for a while.
The gurgling sound is definitely bubbles rising through fluid. I guess in the heater matrix in the dash. If I turn the climate controls up to maximum heat, there is no sound at switch of but if the climate controls are turned down halfway or lower, the sound is there.
I tried running the engine for a while with the cap off the header tank but it made no difference. I can't see any bubbles in the header tank either.
So, airlock in the heater? Any ideas?