[babek1]

Hi all,

I have a 2006 330i E90 (N52 Engine) for which I try my best to take great care of. All of my fluids are up-to-date. I have been noticing the following issue which began about 1-2 months ago:

- during a morning start, I notice that my engine fan will intermittently turn on and off, then repeat. It turns off after about 1-2 minutes of driving. I would guess that the fan goes to 70% strength, falling to 30% speed then repeat.

- I am not 100% sure about this, but I believe this gets triggered when my internal vents/air flow are turned on. If they are off, I don't believe the intermittent engine fan goes on/off repeatedly. I will need to test this further though to be 100%.

Why would my engine fan need to go on/off like this? Isn't it only supposed to kick-in after the engine temperature is quite high? Also, it's quite cold outside nowadays (Avg. 5 Celsius or ~35 Fahrenheit) so why would the fan be on?


My vehicle currently has 140,000km (~87,000 miles) and I fear that my water pump might be dying. What do you all think? Do you think that this issue would produce an error code that my indy dealer could pick-up with a scanner? I have never replaced the water pump/thermostat on my car.

Any advice is greatly appreciated!

[babek1]

I can say with more confidence now that the intermittently on/off fan during a cold start is indeed linked to whether or not I have my car's air vents on inside the cabin. I tested it out this morning during a cold start, and then again after work when the car had been parked for over 10 hours (therefore another cold start).

In other words:

- if I start my car and the vents are not on, then the engine fan will not intermittently turn on/off.

- if I start my car and the vents are already on, or if I turn them on right away, the engine fan will definitely begin to intermittently turn on/off for a few minutes.

Can this still be related to my water pump, which I have never had replaced before?

Any insight/tips/advice is greatly appreciated!

[babek1]

Just got an update: my BMW indy-shop scanned my car and it indeed is the water pump which has been registering slow-speed error codes. In other words, the water pump is dying and needs replacement soon.

I'm going to get both my water pump and thermostat replaced as soon as possible. I recently flushed out my coolant so won't need to do that again except for the shop topping-up coolant during the new pump installation. Again the car has about 140,000 km or ~87,000 miles which I figure is the normal mileage for such a replacement.