Heater problem

Hi
I’m having problems with the heater with my Discovery 2 V8 heater, it works fine when the car is moving or the engine is revved over 1000rmp but just blows cold if the engine is ticking over? As you can guess this isn’t good given current climate
I have bleed the system and am pretty sure there is no air lock and am not losing any coolant, the engine doesn’t over heat. This has got me stumped!! I did notice yesterday morning when I was checking the levels that when I opened the expansion tank there was pressure in the system even though the car hadn’t moved for over 24hrs? Is this normal?
Could this be the water pump on the way out and not working as it should unless the engine is revved?

Any advice gratefully received
Cheers
Stuart

I would get a pressure test done mate to be sure there is no other problems. The V8's can be a pain to bleed properly but can also suffer other problems. Pressure testing is the only answer.

My 3.5 was a pain to bleed but I've never had a problem with the 3.9. The pump only circulates the coolent, the reservoir cap and the heat of the coolent sees to pressure part and no you should have no pressure as you have done when you released the cap so if it's not just a one off then theres a problem, may be just an iffy cap not allow the presure to drop when the engine cools.

Are you sure the dampers are opening in the heater but if you have climate control then there could be a problem there with the all valves and sensors cc has..

Hi, i am not very technical i am afraid, but when my car did this it apperently just needed water in the radiator,

Right, i think i have cured this with a simple change of the expansion tank cap!! discool got me thinking with

discool said:

My 3.5 was a pain to bleed but I've never had a problem with the 3.9. The pump only circulates the coolent, the reservoir cap and the heat of the coolent sees to pressure part and no you should have no pressure as you have done when you released the cap so if it's not just a one off then theres a problem, may be just an iffy cap not allow the presure to drop when the engine cools.

Click to expand...

I now have a HOT heater all the time not just when accelerating. Thanks discool

BUT I have noticed a rushing water type sound coming from the heater matrix when pulling away? Does this mean I haven’t bleed the system properly? I did follow the instructions on the rave cd to the letter Is this an air lock and if so will it work its way out?

Cheers

Stuart