So last month I changed my radiator as the bottom fell out.
Sorted that and was all ok so to speak.
Driving to and from work very short 15 min run no issues so I thought .

So was on the Motorway last weekend and she started to creep over half and upto and no further than 3/4 .
I eased off from 80mph down to 60mph and she seemed to settle at norm half way temp.
During the journey various times it increased and settled along the way BUT never overheated as such just got hotter than norm.

So today I have replaced the thermostat and have bled the cooling system as described .
Car on Ramps and ign on and hot temp settings and all that .
10mins bleed and ready to start .

So this is where I now want reassurance.
I run the engine for bloody ages and that bloody bottom hose was still stone bloody cold .
I mean it was idling for a good 25mins . Gauge was in middle still. So I went on a road test and give it some . Pulled over and let it idle . Still cold bottom hose .
I revved it to 3500rpm and the viscous kicked in so I assumed the rad was at its hottest and needed cooling . Still revving at 3.5k the fan Shut up so to speak so again I assumed the cooling was done and all was happy .
I let it idle and the bottom hose was bloody cold . I now think there must be air in the system coz that bloody hose isn't hot .
Anyway pulled up on the drive way up on the ramps and left it idling . So I thought , I know I'll stop the viscous from turning and left the bugger get hot .
I did this and yay the bottom hose starts to get hot , so much so that I cannot hold it any longer "Bloody HOT" , so I'm thinking jobs a goodN.

Now here's my question .
After I released the fan blade and the hose was hot I increased the revs to 1200rpm and waited for the viscous to shout . It did and I let it idle at that point .
Here's the odd bit I don't get .
The viscous shouted at idle for so long it made the water in the rad and the bottom hose cold as I was holding the hose and checking its operation .
I don't think this over cooling should happen like that , have I got a viscous now that's holding on for too long and over cooling ?
Do these BMW's always have bloody cold bottom hoses .
I'm still stumped .

Oh and I've not been out on a motorway run yet as I don't trust this car so to speak yet all because the bottom hose is cold again , as it was last week when I double checked and bled the system after work in the week . That's why I went for a thermostat . Seems to me I'm in the same predicament with this bloody car .