Posted by PeterW on March 09, 2004 at 01:21:16:

In Reply to: 1999 Discovery SE Coolant problems posted by Ed on March 08, 2004 at 15:36:08:

That sound is a heater with an air pocket.

As to these statements - I'm a little confused.

" I'll notice that my coolant is too low to properly operate the heat" and "There are no apparant coolant leaks that I can find"

Is the vehicle using coolant ie. are you topping it up???

If you are topping it up, then you have a leak.

If not, then the system needs bleeding - it has air in it.
BTW, this can also be the case with frequent top ups as people just add coolant and don't bleed.

HTH

PeterW