COOLING FAN RUNNING CONTINUOUSLY

[Alli26]

Hi all,

Was hoping to get some input from some of the older BMW diesel boys. I've got an E82 120d, with approximately 255k on the odometer. She doesn't drop coolant nor oil levels, serviced every 10k etc - well maintained. Recently however, I've noticed the cooling fan tends to run excessively, often at full tilt, after only a few mins of traffic light to traffic light driving - no codes stored on the ECU and inspected by 2 competent BMW mechs - neither can seem to find anything wrong. If I pull off the freeway and park the vehicle off relatively quickly, the fan often will not run. She never feels hot to the touch and doesn't display any overheating symptoms.

I've already changed the coolant temp sensor, but no real change. Should I go the water pump and thermostat route or is there something else I may be missing?

Any advice is welcome,

Thanks

 

[Teezoh]

Sounds like you've done a solid job looking after her, especially at 255k. Given the symptoms, I'd definitely lean toward replacing the thermostat and possibly the water pump, especially if they haven't been done yet. Even if they're not completely shot, they can start acting up in subtle ways at that mileage.

Also worth checking: does the fan behavior change when the AC is off? Sometimes, a faulty AC pressure sensor can trigger the fan to run full blast, even when the engine's not really hot. Another oddball possibility is if it's doing a DPF regen, those can make the fan run more often and for longer than you'd expect, especially right after a drive.

You could also try pulling live temp readings with something like INPA, ISTA, or even Torque Pro, just to see if there’s any sensor feeding strange data to the ECU that isn’t bad enough to throw a code.

But yeah, at this stage, I’d say thermostat and water pump are a good shout, cheap insurance either way.

 

[Alli26]

Sounds like you've done a solid job looking after her, especially at 255k. Given the symptoms, I'd definitely lean toward replacing the thermostat and possibly the water pump, especially if they haven't been done yet. Even if they're not completely shot, they can start acting up in subtle ways at that mileage.

Also worth checking: does the fan behavior change when the AC is off? Sometimes, a faulty AC pressure sensor can trigger the fan to run full blast, even when the engine's not really hot. Another oddball possibility is if it's doing a DPF regen, those can make the fan run more often and for longer than you'd expect, especially right after a drive.

You could also try pulling live temp readings with something like INPA, ISTA, or even Torque Pro, just to see if there’s any sensor feeding strange data to the ECU that isn’t bad enough to throw a code.

But yeah, at this stage, I’d say thermostat and water pump are a good shout, cheap insurance either way.

Thanks Teezoh! I'll try taking her on a 45 min drive up the coast and monitor the live data. If no luck, then water-pump and thermostat next.

Also, no real change with the AC off. It will tend to kick in the fan quicker with the AC on, but doesn't necessarily turn the fan off when the AC is turned off.

 

[Alli26]

Sounds like you've done a solid job looking after her, especially at 255k. Given the symptoms, I'd definitely lean toward replacing the thermostat and possibly the water pump, especially if they haven't been done yet. Even if they're not completely shot, they can start acting up in subtle ways at that mileage.

Also worth checking: does the fan behavior change when the AC is off? Sometimes, a faulty AC pressure sensor can trigger the fan to run full blast, even when the engine's not really hot. Another oddball possibility is if it's doing a DPF regen, those can make the fan run more often and for longer than you'd expect, especially right after a drive.

You could also try pulling live temp readings with something like INPA, ISTA, or even Torque Pro, just to see if there’s any sensor feeding strange data to the ECU that isn’t bad enough to throw a code.

But yeah, at this stage, I’d say thermostat and water pump are a good shout, cheap insurance either way.

Update: I've gone ahead and purchased the thermostat and water pump (Goldwagen) anyway - rather safe than sorry. Getting them installed tomorrow and will update with results.

*holding thumbs*

 

[Alli26]

Final update: new water pump and thermo procured from Goldwagen - issue appears to have been resolved. Good call Teezoh.! 🤙

 

[Teezoh]

Glad you got it sorted!