I don't think the BMW engine has an electrical coolant pump. If it hasn't then you will have no coolant running until the engine is running.

Have you replaced the water pump yet ?? I seem to remember that the BMW V8s has an issue with vanes disappearing although that would increase the heat of the engine so unlikely to be causing your current problem.

If the coolant is going into the expansion tank on start up, I would say could be an air issue. Although the engine temp is increasing, that should be with the closed thermostat so no water going into the radiator and therefore expansion tank.

It almost looks like there could be a thermostat problem again. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

Have you downloaded the workshop manual of your model yet ?? Have a look at the cooling system.

There is a heat exchanger for the transmission oil. On my SC I had two and both blew within months of each other. The transmission was the first to go (weak point of the ZF system in those days). The box didn't like it so it started acting up and the coolant was also full of oil so the expansion tank overflowed with brown sludge.

In other words you would know if that cooler leaks but still, something to check since it could disappear there without a trace.

I think it is unlikely the problem is there as you would have gear shift issues etc.

Still the workshop manual gives you a good look at the cooling system though. MY 2010 5.0 SC Galway green and sand interior!!
Have the Faultmate MSV2 Extreme to be tinkering with the settings etc. !!

There is an auxillary electric heater pump in the highline system (independent temp for driver and passenger)

Extract from Rave....

Rest Heating (High Line System Only)
When the engine is not running, pressing the maximum A/C switch activates the rest heating function to heat the
passenger compartment with residual heat from the engine. The rest heating function activates provided the following
conditions exist:
l It is less than 15 minutes since the ignition was selected off
l Ambient temperature is less than 15 °C (59 °F)
l On the previous ignition cycle engine temperature exceeded 70 °C (158 °F)
l Battery voltage is 11.4 V minimum.
To provide the rest heating function, the ATC ECU activates the auxiliary coolant pump, coolant valves, control flap
and blower. The ATC ECU regulates the temperature (to the driver setting selected before the ignition was switched
off), opens the face level distribution flaps and runs the blower at speed 4.
The rest heating function is cancelled after 15 minutes or when:
l The maximum A/C switch is pressed again
l The ignition is selected on
l Battery voltage decreases to less than 11 V.

So try that and see what happens....

The pump is attached to the two heater valves on the left hand (whilst sitting in the car) inner wing near the exhaust manifold Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

Thank you!

I tried this. Started blowing but was dead cold. Or lukewarm. No idea what that tells me though.

Might be blocked heater pipe to/from the pump, or as it gets hot it collapses, worth having a good rummage around all the pipes to see what you can see, take them off if you can and stick a hosepipe through it... Or

There are several flushing treatments you could tt on the whole system.... Pete

__________________________________________________
2014 L405 Autobiography SDV8 4.4 Loire Blue Ebony interior
2011 L322 Vogue SE 4.4 TDV8 Baltic Blue. Parchment over Navy Interior. Sold
2012 L322 Autobiography 5.0 Supercharged Ipanema Sand, Jet Interior. Sold
2002 L322 Vogue 4.4 V8 Epson Green, Ivory over Aspen Interior (Fatty Offroader) Sold
-Click for Project Fatty off roader-

THis is starting to drive me quite insane.

I tried driving the car on high revs earlier today. The heater then lastet all the way (around 15 min). Blowing not warm, but kinda warm. Like if I had set the heater for 19-20 degrees.

Drove home from work a bit later. Then it was back to blowing cold again.

Blimey. I've had the FFRR 5 years and I didn't know about the rest heating function!

I won't point out its in the manual.....

To be fair, whenever I buy a car, I take the manuals away when I agree the deal, and read them cover to cover, a few times whilst the garage preps the car for delivery...... Most of it sinks in !

Not normal I know  2011 Range Rover Vogue SE 4.4 TDV8

Previous cars :
2003 Range Rover Vogue TD6
1999 Discovery Td5 ES
1995 BMW M5 3.8 6 speed
1992 Range Rover 3.9 Efi Vogue
1992 BMW M5 3.8
1988 BMW 735i SE
1989 Ford Sierra XR4x4 2.9i
1981 Ford Fiesta Supersport

so, I have to things i can try. Flushing the heater matrix. Anyone have a good tip how to?

And, I can check the current on the auxiliary pump to see if it works. What and how to I check if it gets the right volt etc?

Haven't read the whole post.... So my bad if it's already been mentioned.

The coolant flow to the heater matrix is governed afaik by the two coolant valves on the inner wing drivers side and passengers side have different matricees hence 2 valves, if these are stuck closed or not opening fully then the hot water will not get the the matrix, and thus heater will be cold. It may be worth testing the power to these and possibly remove and bench test them to see if the actually open and close when some power is fed in. There is nothing that can't be fixed with a hammer😜😜
FFRR 4.4 SDV8 Autobiography Santorini Black.
Fiat 500x 1.4 multiair Lounge 2015
2010 LR D4 Commercial 2.7 TDV6

I agree with the monkey above . If you standing at the front of the engine bay looking, the 2 valves sit upright against the right hand wing as you look into the engine. You'll see the coolant pipes from the bulkhead and do a 180deg turn back into the valves. These sit quite close to the exhaust manifolds and I found on mine that the wires and connectors not he valves felt like they were were brittle / slightly corroded. I unplugged the connectors, gave all the contacts a good clean, and this seemed to sort out some poor heat I was having.

As for filling the system, it takes time and patience. Its not the type of system to throw coolant in and drive off. It has to be done right, with proper use of the bleed screw on the expansion cap. V8 or else ...

I took the valve out earlier this year. but the torx were corroded. So i sort of gave up. Now I am freezing to death so I will give it another try. Must just find out how to get the broken torx of and where I can get new ones if i succed getting them of.

If I flush the heating system at det same time, will this flush the heater matrix at the same time? Found a way to flush that as well, but if I can skip having to detach more hoses than necessary that would be great. But will of course do them both if its for the best!