Now that I do not have my heater running all the time, I have noticed a gurgling sound from the dash or somewhere below. It does seem to be constant, ,however it does get a little quiet(er) sometimes. Water boiling sounds close to the noise also. Strange? Heater core flush, purge, air release??? Thanks all.

 

Sound seems to be coming from behind the center air vents. Any thoughts?

 

I have a 99 XJR which has a loud noise that comes from behind the centre vent, to me it seems like squeaking of the corrugated air vents that will no doubt be feeding the vents. It goes after a while but not before it has driven you mad. I was wondering how to get the top of the dash panel off to take a look. I wonder if its the same problem as yours