A4 b8 2.0tdi 105kW problem with coolant temperature

[Renars]

No, I didnt but I think it is normal behaviour when I on motorway temperature sits on 90 degrees and when I'm driving on local city streets and heating is set on 24°C there is a little oscilation on temp gauge where not sitting on 90. I'll leave it like that will not care anymore.

Yes, it is normal behavior, because you are drawing heat away from coolant with cabin heater and engine in low load cant produce much heat.
Temp gauge shows 90 from around 75 to 120 degrees C. Thats how its designed

[Renars]

I'm freezing with 24ºC. If I set my heating on 26 ºC I feel a little heat only after 5-6 km. Temp outside is 8 - 13 ºC these days. It would be interesting to test our thermostats. Does it really open at 87 ºC or less?

Your coolant temp gauge will show 90 long before thermostat will start to open at 80 plus degrees.
Also cabin should be blasted with hot air long before that.

[doktorrrr]

Just to refresh the topic. Does anybody solve the problem with drop temperature? I have no problems in the summertime with Audi A4 B8 2.0 TDI 2013. But, this weekend I was on the mountain and temperature outside was about 2 degrees. My temp gauge was on the 50-60 degrees next 30 km. I was no heating in the cabin. Only after I came to the city (+10 degrees), my temperature gauge reaches 90 degrees.
Just to let you know, my both thermostats are replaced in the service dealership (two times). I also have Passat 2012 with the same 2.0 TDI machine. Passat doesn't have the problems at all in the winter time. Temp gauge is stack on 90 degrees and the heating in the cabin is excellent. So, I think that this is not normal behavior.

[Renars]

To make it clear !!!
Temp gauge DOESN'T show real temperature.
It shows 90 degrees from around 70ish to over 100. Its designed that way so you don't go to dealer asking why temp is moving around all then time,
but as we can see that haven't worked
In city driving if outside air temperature is close to 0 degrees modern diesel can not reach coolant temperatures of 90 or even 60 degrees even with thermostat closed and coolant not going to radiator, because your cabin heater is pulling all the heat out of it.
It will warm up only if its under load for quite a while - highway drive.
That's why its way more economical than petrol nonsense.

[doktorrrr]

I have a laser gun for temperature in hoses. The difference between the gauge and hoses is about 10 degrees. I'm aware that t

emp gauge DOESN'T show real temperature. However, difference can't be more than 10 degrees. What if your car is overheating and temp gauge is lie for more than 10 degrees and show you that everything is normal?
So, t

emp gauge DOESN'T show real temperature, but not too much. We talking about coolant temperature drop for more than 30 or 40 degrees than normal 90 degrees in downhill drive or idle. Sometime, I wait for green light on the semaphore and I see how the temp gauge drop for 10 or 20 degrees.
Also, in the summertime temp gauge is fine in the driving. It's stuck on the 90 degrees. But, I have noticed something strange. After long drive (outside temperature is about 30 degrees), and parking the car for 5 minute pause, when I'm starting machine again, temp gauge is on the 50 degrees. How can be possible that coolant temperature is drop from 90 to 50 degrees for only five minutes pause on the 30 degrees outside in July? Something in the cooling system doesn't work correctly, but car diagnostic doesn't show what is it.

[Renars]

You could use VCDS to see real coolant temperatures in at least 6 different places for your car.
Difference is way more then 10 degrees.
House after radiator could be minus degrees while engine gauge at 90 already since thermostat starts to open at 83 degrees.
Gauge will go to red section when coolant will reach dangerous temp, that's how its programmed !
Maybe next time check while driving with VCDS or any reasonable diagnostic tool, it will show you real situation.
While heating up your cars coolant even not pumped around and stays still to warm up quicker.
Before your laser gun experiment, please, do more reading on modern cooling system technology, its gone way different since 1980 now !

[Renars]

You are talking about coolant system as one loop, but its at least 4 different loops.
Lets say you started car dead cold in morning and its 0 degrees, then you are driving on country road for 5 minutes temp gauge is at 90 BUT thermostat is yet to open because its really never been over 80 degrees, its looping through engine and heater matrix only and that's like 1,5 liter of coolant. As you stop and idle your heater is pulling massive amount of available heat out of this 1.5 liters of coolant and of course it cools it down very rapidly !

[Novica]

I have same issue with my A6 2.0 TDI, 2011 C6 model (2008-2011), engine CAGB. I have changed main thermostat and hose thermostat, no change. I didn't change non return valve. No change, during outside temperature more then 10 degrees everything is normal, when outside temperature goes below 10Deg C, engine tempereture is depending on engine load.

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[Glen Norman]

Should be yes!

Rura wąż wody Audi A4 8K0 B8 03L121157B 1K0121113A VAG. Nanodatex

It might be a bit late but a very good flow digaram.
Diagram of coolant hose connections

[Mio&drag]

Same problem here. Replaced regular thermostat Vernet 82°C also replaced Behr th5 75, but still dropping temperature if I drive out town, on lower RPM. Same Audi Caga 2.0 tdi a4 b8 105kw engine.
Next should be the valve? Does all 105kw has this valve?
(Picture with diagram is no longer available...)


Recent update:
Problem solved by replacing the valve
1J0122351 in hose.
I had two termostats Behr th 5 75 both in hoses. Probably previous owners service guy mixed them up.
Changed the upper part in hose (upper is the valve, lower is the inline thermostat). Tried the car for 20km, with heat on the max, and everything works fine! Glad if this helps anyone.