2005 4.4 V8 petrol

No heat from any vents only cold air, all vents work though. Thumb wheel is on 3 red dots. I have topped up & bled coolant, Replaced pollen filter. Blown air over internal temp sensor below passenger heater control. Replaced (with 2nd hand) heater matrix valves & low speed (idle )pump. Today I have checked the voltage at the heater matrix valves to earth With key off & on & with temp setting of 16 & 26, 2 had 1.8v n the other zero No change at all Checked voltage again a foot further up the loom as I know the connector & wiring get very hot from the exhaust. No change at all. Very frustrating Any ideas are appreciated

All the above had been posted by fellow forum members Many thanks to them.

Last edited by Ridgeback on 15th Jan 2019 9:39pm. Edited 1 time in total

You have my sympathy, looks like you've tried everything .

I've checked most of the items as you have. Although my issues appear to be the auto temperature settings, rather than no hot air.

Are you sure that you don't have an air lock?. Have you traced the pipes back, confirming that hot water is going all the way around the system.
Surely if you have hot water to the matrix & the fan works, then in theory you should have hot air

Apart from this I have no further ideas.

Hopefully you can get it working .

Sandyt had this problem as did I. It has possibly something to do with the heat exchanger in the front engine bay. I fixed mine by removing and reinserting the pollen filter. It worked after several attempts. Still don’t know why but it’s been fine since (4 years)

Many thanks will follow the hot water n recheck pollen filter

Pretty sure you still have air lock they can be a swine to bleed I found a good way to bleed was using a 2litr bottle of coolant and stand upside down on expansion tank open bleed screw and run engine keep a full bottle ready to replace do not allow expansion bottle to empty make sure heater control is at max .If that don't work you may have a blocked radiator good luck

Many thanks for the replies Tried bleeding it again still the same Bit the bullet n took to my local RR specialist Landypart Woodbridge They put a fault reader on & forced the heating system A code was up n was cleared n returned A thermostat Not sure if this is coolant system or heating £260 to replace Will advise what stat when I know n if it worked

Update us all once you have it sorted.

Dolphinboy - I have removed & re-seated my pollen filter, just to make sure that there was nothing blocking it. Question how this would cure it, as there is nothing behind it?. Just the main air inlets.
As a thought do you run with the air re-circulating on or partially on?.

I still believe that mine is down to the engine bay valves.

Which engine bmw or jag ?

UPDATE

thermostat replaced for heating system (not coolant) still no heat Can get it to heat sometimes via lap top So heater control unit replaced (Dash panel) still no heat Now suspects blend motors / flaps but 2 days labour to remove dash to gain access but to be fair to landypart they have only charged me a couple of hrs labour & said if they take the dash out they won’t charge me for the earlier work Now have a cold journey to & from Gatwick I will bite the bullet & have dash removed Looking at other sites could be a blocked matrix internally or externally broken cable / connector

I heard of a way to bleed these things is to jack the front of the car way up.

Apparently this helps to persuade any airlocks etc to the front of the car and facilitate bleeding.

I had the no heating problem when I changed out my radiator, everything was getting hot including the little heating pumps leading to the matrix etc, and I just couldn’t fathom it. I had a look on one of the BMW forums and saw the jacking up trick, and it worked, mind you this may not be your problem but you did say at the beginning that you topped off the coolant and bled..

Here’s the link , https://www.meeknet.co.uk/e31/E31_Cooling_...eeding.htm

Regards ______________________________
Simon
______________________________

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Thanks Simon

Tried some of procedure but found top hose started to drip / leak when squeezed I’ll change this 1st

Just a thought I had to seriously overhaul the whole heating system and found that there was a another valve on the bulkhead which was connected to the FBH (mine is one of the few petrols with it) this was my main culprit the valves on the inner wing were replaced but the one on the bulkhead was stuck shut and not allowing any hot water to the matrix there was no airlock
Have a look at that

Mine hasn’t got the FBH So does it still have the valve ?

Not sure to be honest if so it is low down where the pipes go through the bulkhead to the heater matrix

Ah that could be why mine was cold .... it too is petrol with an FBH. Maybe taking everything out allowed the bulkhead valve to open?

Last edited by Dolphinboy on 9th Dec 2018 7:51pm. Edited 1 time in total