I have a 1997 Disco I and I replaced the upper hose and thermostat. I have tried bleeding the system for the last 2 weeks and still have the gurgling noise in the heater core. I have heat and the engine is not over heating, when I drive it, but the noise drives me crazy. Here is what I have I done:
With vehicle cold
Open the reservior cap
Open the bleed screw/removed it on the radiator
Filled reservoir to top and until fluid came out of bleed hole
Turned heater on low
Ran truck until it got hot, both heater hoses hot to touch and upper hose hot
Ran truck between 2-25OO RPM for several minutes
Fluid will run out of bleed screw and level drops in the reservior
Can jumping on the throttle to push air out.
Replace Bleed screw
Replace Reservior cap
Turn truck off
Air still in the system

Can anybody tell me if I am doing this right, any help would be greatly appreciated. Almost to the point of taking it to my mechanic to have him do it.

Thanks

 

The heater needs to be on high to bleed properly. Temperature all the way to hot and fan on high. Have you tracked down how the air got in the system? You have a leak somewhere that is allowing air in. Until you find the leak you are wasting time bleeding the system.

 

The heater fan does NOT need to be on high, the heater does not know or car what speed the fan is set on.
Try this, switch the heater lines, bleed the system and then switch the heater hoses back to their correct place and bleed again.
You have a stubborn air pocket and sometimes reversing the coolant flow will force it out.

 

do what spike said, you have scale in the heater core, youll clear it out by doing that

 

what are the heater lines? are those the hoses coming out of the reservoir tank?

 

The 2 large hoses that go thru the fire wall on the passenger side.