Radiator fan excessively going on/off (video)

[esg]

Hi, I drive a 2006 BMW 330i with 118XXX miles. Recently, I've been having a lot of issues with my coolant system. I've replaced my lower radiator hose, upper radiator hose, coolant temperature sensors & about to replace the waterpump/thermostat this weekend.

Anyways, as the title reads, my problem is that my radiator fan is excessively going on/off. About 10 seconds after I start the car the fan turns on and repeats doing so every 3 seconds or so. Even on a cold start, so it's pretty strange. I recorded a video, I'll include the link below. Could this be the waterpump or thermostat failing?

https://www.youtube.com/watch?v=yhAC4TG3WK4

also - every time I coolant flushed for each repair of hoses, I never bleeded the cooling system (I know I'm dumb for not doing so). This may be the reason my waterpump is failing. (if it is)

[dworthy]

Have you tried to bleed the system? It only takes 10 minutes and ZERO tools. https://www.youtube.com/watch?v=60X3x_ihww8

[bmwdirtracer]

The electric fan beginning to blow right after starting the cold engine is a sure sign that your water pump is failing. The computer knows that the water pump is drawing too much power, so it's protecting the engine the only way it can....well almost. It can actually flash warnings of impending doom, and shut off the engine too....that's next in line, if you don't fix the issue.

There will be codes in the DME for this, by the way.

Have the water pump and thermostat replaced, and the cooling system bled.

To bleed: fill reservoir slightly above full mark, turn on ignition but do not start engine. Turn heater to full hot, heater fan control to "low". Then hold your foot fully down on the gas pedal for 15 seconds. Then get out and look into the reservoir. You should see a stream of coolant flowing there. This stream will come and go for the next 12 minutes. Best to do this with a battery charger on.

[esg]

Have you tried to bleed the system? It only takes 10 minutes and ZERO tools. https://www.youtube.com/watch?v=60X3x_ihww8

Yes I have, it actually drained my battery when I tried to do it. My battery was already bad as it was and it completely killed it. Charged it and will only last 2 days. I'll have a charger connected the next time I bleed the cooling system. Thank you for your input!

- - - Updated - - -

The electric fan beginning to blow right after starting the cold engine is a sure sign that your water pump is failing. The computer knows that the water pump is drawing too much power, so it's protecting the engine the only way it can....well almost. It can actually flash warnings of impending doom, and shut off the engine too....that's next in line, if you don't fix the issue.

There will be codes in the DME for this, by the way.

Have the water pump and thermostat replaced, and the cooling system bled.

To bleed: fill reservoir slightly above full mark, turn on ignition but do not start engine. Turn heater to full hot, heater fan control to "low". Then hold your foot fully down on the gas pedal for 15 seconds. Then get out and look into the reservoir. You should see a stream of coolant flowing there. This stream will come and go for the next 12 minutes. Best to do this with a battery charger on.

I haven't driven the car since the day I found out about it so it should be fine... hopefully. I'll be replacing the waterpump & thermostat this weekend, and properly bleed the cooling system. I'll keep you guys updated. Thank you for your input! Do you think not bleeding the cooling system put a lot more wear on my waterpump?

[dworthy]

Not really as it would be running driving down the road, just a different speeds.

Also when you go get a new battery, make sure you get it registered with the DME, otherwise you will be overcharging the battery and putting it in an early grave.

[esg]

update:


I can confirm it was indeed my waterpump or thermostat. Followed the proper bleeding procedure. Fixed my problem. Thanks everyone!

[dworthy]

Good to hear!

As a side note, most water pumps and thermostats only last around 10 years on the N-5x motors, since you are in that window, I would start looking at getting it replaced to ensure you won't have any other problems in the future.

[bmwdirtracer]

I think the OP means that he just replaced both items, THEN bled the system?