Yes miggit down to two ' bleeders ' now

Mine is going to full left while going down a cold mountain.
But warms up fast to 12 oclock when climbing.
And also warms up toonlate in mornings.
Is viscous capable of this much cooling?

06 td6.

You have to remember that Diesel engines can over cool even with all the thermostats operating correctly and fully closed. Unless working hard the engine simply doesn't produce enough heat to offset the cooling effect produced by air flowing over the cylinder block. Going down hill in cold air is the very situation that overcools the engine, due it hardly producing any heat, whereas going uphill in the same air temperature will likely result in the engine temperature returning to normal.
Removing the viscous fan helps stop the over-cooling effect.
I ran my Discovery for years without the viscous fan fitted, summer and winter, without any problems at all.
Haven't done it to the FF yet but it is under consideration.

I believe that kingpleb runs a viscous fanless ffrr  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

I really enjoyed reading all this until I hit the same problem. I was losing coolant from the EGR cooling system (I could see the drips BELOW the system pipework) and also was getting the infamous white steam from the exhaust. I removed the EGR valve but the steam continued (albeit for less time) and I was still losing coolant. So I removed the EGR cooler, blanked the pipe ends and the exhaust EGR outlet. Got rid of the steam (white smoke) but the temperature gauge now never reaches normality. Like most other posts it drops back on downhill runs and nearly reaches the 12 o'clock position on a steep hill. The thermostat was changed with the water pump about two months ago using a Eurocarparts kit. I have 2 options. Try bleeding the system again or change the thermostat for a genuine LR part. I have heard that the LR part is optimised for the Range Rover fit to avoid the engine running too cool. I could do with sorting this as I would like to see an improvement in my fuel consumption (it improved a bit after the EGR system was removed but it would be better if it ran at the correct temperature) Is there a neat way of bleeding the system (eg. car facing downhill at normal operating temperature like a BMW E36!?)
Any thoughts?

Right I may be able to shed some light on this...

When you removed the EGR cooler, did you blank the water pipes, or did you joint them together?

Because if they were joined together then I can see that there may be a problem, due to the open flow.. this is in turn short circuiting the main cooling system and causing the car to run cold under normal operation.. somehow the flow needs to be restricted where the EGR cooler was, cos that cooler had it's own thermostat and you have removed it  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

should be possible to adapt something like this to sort it out...

http://www.ebay.co.uk/itm/2008-HONDA-CBR-1...xyyFhTedni

you'd need to blank the small pipe  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

Reckon that this would be better

http://www.ebay.co.uk/itm/Thermostat-38713...1970790712 Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

Thanks for the reply Miggit.
I removed the complete EGR and cooling system, blanked both supply and return cooling pipes (see photo). I didn't join them so there is no coolant flow. I blanked the exhaust (the blank came with my EGR removal kit). Initially I just blanked the flexible metal joining pipe from the exhaust but the flexible part failed after half a mile so it had to come off and the proper blank fitted - awkward but do-able without stripping the whole front end again.

But is there a recognised way to bleed the cooling system?

Yes there is a way to bleed the cooling system.. but .. you have done away with one of the bleed points..D'OH!

From memory, you open the all the bleed points and fill the system, as each bleed point starts to weep you close it.. leaving the header tank till last... then run the engine with the cap off the header until the car has got to temp... topping up as you go... once your at normal temp give it a few minutes, check that the heating in working, do a final top up and seal the system.... Recheck the level when the engine is cold (overnight)

Now the fact that you have removed one of the bleed points could be causing the trouble.. there could be an air lock at the front of the engine... I might be tempted to extend the blanked pipe on the left (which would have been the one nearest the bleed screw) to a higher point and let it vent as the system is filled.... But adding a thermostat in place of the cooler would restore the flows to factory... by blanking you may have caused an airlock  Yesterday I couldn't spell Engineer... Today I are one!
Inventor of the 'Guide-o-Matic automatic wheel alignment tool'
Former long term L322 owner, Up/Down graded to a Classic Tractor!

Having done exactly the same mod as mariner30 about 6 months ago I have had the same temp. fluctuation problem. Temp. gauge slow to reach normal pottering round locally once wound up on motorway gauge drops to 1/4 or below leading to no heating. Am planning to change main thermostat for genuine LR part and try again. Find it hard to believe it could be air lock problem but you never know!

Yes diesels can cool but we also have an 03 td6 it is way difeerent.
Inside temparature is also affected a lot where 03 isbmore stable.
Will try some solutions.

Does anyone know for a fact that the genuine LR TD6 thermostat is optimised for this vehicle to prevent over cooling??!! If this is so then maybe their high purchase price starts to look more acceptable?!

My Td6 was/is bog standard.
It's coolant temperature was never exceeding 78ºC so I replaced both the main thermostat and the EGR thermostat, the former with a Gates pattern part, the latter with a BMW part.

Since then the coolant has been rock solid at 92-93ºC doing everything from caning it along the autoroute in OAT of mid-twenties, to bimbling along A-roads at temperatures of 1ºC.

I therefore conclude that a Gates 'main' thermostat behaves exactly as BMW intended, and that the genuine part has no mystic properties.

Does lower operating temperature have any advantage??