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I have the same issue and have tried the decarbonize trick but it doesn't fix the issue for me.
I'm a bit curious if the blockage of hose number 12 in this pic RealOEM.com - Online BMW Parts Catalog
Where do you block the hose? Next to the radiator? About where number 12 is? I would guess closer to the radiator because of how hose 11 looks. Have I understood this correctly if hose 11 is supposed to replace hose 12, depending on the radiator?
My fuel mileage ain't too bad so this isn't a huge problem, but there's quite cold here in Sweden some days and it would be nice if the temps can rise quicker than it does today. It takes about 15 km of highway driving for my car to go up to the correct temperature when the temp is 3 degrees celsius or higher, weirdly enough the temp rises a bit fast when it's colder than 3 degrees celsius.
Hello.
In the realoem diagram below is the part that isn't necessary anymore. the red is of the section missing from number 11 and the yellow is where mine is now blocked (roughly). So yes number 11 is a replacement for part 12 for the manual radiators, I decided not to replace this but just block it off completely.
To test this out I used the clamp in the image below so not to cut or replace any hoses. As soon as I noticed everything working perfectly after driving with that clamp on, I went ahead with permanently blocking the hose. Has been perfect ever since. Worth a shot since this is reversible.
Thanks for the response, I'll see if I have the same hose (which i should) and try to block it off.
How did you permanently block the hose? I Guess you don't drive with the hose clamp on all the time?
I only had the clamp on for 1-2 days just to test if it actually worked, which it did. So I then took the car to a mechanic and asked them to block it. Unfortunately I'm not exactly sure what he put in it. But I know it was cut where the yellow line is, and then a hose connector that's blocked somehow was put there in between the hoses. That's all I know sorry. Hopefully it's a success for you too.
Sad to say that my issue isn't solved yet. I have ordered a IR thermometer to see if I can find anything interesting, otherwise it may be that I "have" to change the radiator as others have done in this thread. I think a bit about the heat exchanger to the transmission, but it feels weird if that function have enough capacity to cool the whole engine for almost 20C / or make the engine run cold at all. I mean if you think of it, how big is the heat exchanger compared to the radiator? Quite small in comparison.
Well well, only time will tell if there's a solution to this problem before I sell the car. I won't give up, however I don't want to spend to much time on an issue that doesn't make the car run bad more than possible some higher gas mileage.
Hi All
I read all the post as a movie . I have same issues started with radiator change(not original). Also thermostat change twice. No fault in computer. I felt like "ok someone will find the solution". But I saw there isnt any certain solution our car is behaiving like a human and it is not predictable. I use my car i the city and around 3.000 rpm. If someone found a way or closing the hose working permanently can u please give feedback? Thanks for your shares.
To my surprise it appears it's not only on/off control, but DME can actually open it as much as needed. One thing that puzzles me is how does this two part thermostat actually work. It has a regular thermostat too and I don't understand how the DME controlled thermostat can give more coolant flow even at 110C when the temp controlled regular thermostat should already be open?
I know this is old but thought I'd comment. The car has a regular thermostat like most cars have where a piece expands when heated and opens the thermostat, I believe it's a type of wax. What is unique is that we also have an electric heater element next to that wax core and the DME can heat it up so that it is hotter than the surrounding coolant and make it open early whenever it wants. If that heater element ever fails the wax core will still work to prevent overheating, only the temperature will remain static.
Ive basicly tried everything to understand why on earth my car has been runing too cold ocassionally for the past 4 years.
I dont care much about it because I belive that runing cold is better than the extreme varation from arround 80 degC to some 105 degC, heard about leaking head gaskets.
My car is now at 210000 km and seems pretty stable in operation except electrical faults like PDC and brooken vires in the rear trunk lid hinges....
But the other week I checked the coolant temp and my bogey was back...😁🤣
Since a week back coolant is at 100-105 in city crusing... as weĺl as on highway > 95 km/h... the only thing I repeatedly have practiesed is putting ignition on in pos 2 ...not cranking eng... just letting the system inlcuding Valvetronic doing the self calibration procedure for like 15 sec... which you will hear and voila its hot again.... but do I belive in this ..noooo ... perhaps if it continuos to work and if anyone else can test it and validate any effect.😎
I will keep you updated ...
11-29-2017, 04:32 AM
re
. I have same issues started with radiator change(not original). Also thermostat change twice. No fault in computer. I felt like "ok someone will find the solution". But I saw there isnt any certain solution 
our car is behaiving like a human and it is not predictable. I use my car i the city and around 3.000 rpm. If someone found a way or closing the hose working permanently can u please give feedback? Thanks for your shares.
