[Dr.Factory]

Hello , I have this problem on my new to me 2010 E91 330d auto n57 engine (245cv).
Car has 250.000 km .
Already replaced glow plugs with module (genuine) .
Seems to run fine: no smoke , EGR seems ok .
My only compliant is high fuel consumption : 25 mpg being very easy on the throttle.
I have no errors checking with ista .

Problem is the radiator fan constantly running !
Once the car reaches operating temperature above 90 c° , it stays constantly on , variating it's speed , sometimes faster sometimes slower but Always on .
When running , ktmp-mom in the hidden menu stays between 97 and 108 °C , but mostly on the high side above 100 c° ( outside temp around 25 °c) .
I have been told it it could be the dpf regenerating that keeps the fan on , but could it be always on ?? I even requested a Regen through ista and went for a nice highway drive , but it didn't help because it still keeps running constantly.
I own the car since 2000 km and I hear more the fan than the engine , it's very annoying .

Should I replace coolant temp sensors ? (Radiator and engine head ? ) .
Should I replace the entire water pump ? Even if operating temps seems normal ?

Thanks for any hint .

[nonford]

Possible it could be the thermostat. It's truly a piece of sheet design, as its held by plastic tabs. When the tabs break, and they do, the stat stays closed. Could be your problem and an easy fix.....

[Andy198712]

Under what circumstances are you seeing those temps? Seems hotter than my N57 but U.K. has a colder climate

[Dr.Factory]

Sorry I thought my car had the electric waterpump ... But I have just found out my car has a mechanical belt driven water pump !

I don't think the mechanic pump is prone to failure , don't know about the thermostat , how could I check it ?
Starting the engine from cold , the temperature raises evenly to stabilize around and above 100 c° . After it reaches 100 ° , the fan starts and is usually very noise when the car is moving , if I stop the car the fan slows down after a couple of seconds... Then it becomes noisy again when the car moves .
Outside temp is 25 C° these days .
Funny thing is that the temperature in the hidden menu isn't affected by the fan , meaning that the fan doesn't bring the temp down , even if it stays on forever I don't ever see the temperature dropping as it should .

The temp sensor is cheap and I could try to change it just for the sake of it ...
I think my car only has this temp sensor in the head , I can't find any other sensor in the radiator ...

Could it be somewhat related to the terrible 25 mpg consuption I always get no matter how I drive ?

[Andy198712]

Yeah worth a try, they normally sit around 90. Guessing coolant level is okay?
Most other things I could think of the car would tel you in ISTA

Belt driven pump on these correct. Wonder if you have an air lock in the coolant?

Has it been mapped?
Can you view injector data on ISTA and see there all reasonable the same?

[Tomnavigator]

Dr Factory,
As an observer, I notice the following observations:

1) Your fuel mileage is very low at only 25 mpg.
2) Your cooling fan is constantly running and never shuts off.
3) Any time the vehicle is regenerating the DPF the cooling fan runs and the vehicle uses fuel to regenerate the DPF.

Hypothesis: Your car may be constantly trying to regenerate your DPF causing the two issues you see. Low fuel mileage and a constantly running cooling fan.

[ptpending]

the fan will run continiosly if you have AC enabled.
By default AC is automatically enabled when AUTO button is pressed on climate control panel.
So i would advise you to disable AC and check if fan will run continiosly.

[Dr.Factory]

Originally Posted by Tomnavigator

Dr Factory,
As an observer, I notice the following observations:

1) Your fuel mileage is very low at only 25 mpg.
2) Your cooling fan is constantly running and never shuts off.
3) Any time the vehicle is regenerating the DPF the cooling fan runs and the vehicle uses fuel to regenerate the DPF.

Hypothesis: Your car may be constantly trying to regenerate your DPF causing the two issues you see. Low fuel mileage and a constantly running cooling fan.

Honestly, this is the first thing I thought !
But I don't get ANY dash light or info about Regen and I don't get ANY code or error in ista !
Car runs fine powerwise and there is no smoke

If I search for DPF functions in ista , the only options are "request forced Regen" (tried and went for long drive, no difference ) and info about last Regen ( frequent regens , indeed... ) .
But there is no option to see if the DPF is actually full or not , like there was for nox sensor on my previous petrol car.

How could I be sure it's DPF ? And what are my options? I heard that removing it is not advisable on these cars.

[Dr.Factory]

It seems that I have found the culprit : inspected the electric fan and found a damaged wire in the connector , the blu-black wire (signal wire?) was interrupted and badly soldered . I made a good soldering , put it back together and now the fan runs when it should and without being deafening loud ! Temps slightly lower also , under 100° ( but it's colder these days ) .
I will try on longer runs but it seems fixed !

Also , did exhaust back pressures test with ista and it's very low and way within the limits , so I think my dpf is fine !

I still have to address the very high and mysterious fuel consumption ...

[Andy198712]

Glad you found the fan issue.

High fuel useage is an odd one? Can you view injector values?

[nonford]

Man, love it when posters come back with the fix! Good Job!

[ptpending]

you thermostat definitely died, because diesel thermostat are not reliable by a history
and since car is driven in hot italy nobody bother themself because engine reach its 90-100 temp anyway
but for emission and dpf and fuel economy it is better to have thermostat checked and replaced