Auxiliary fan noisy

[paplip]

Last month, the front end of my E39 was wrecked and just got it two days ago. I have a new radiator and fans. The electric fan in front of the radiato is very noisy, the kind of noise from a very fast and loud fan. The engine is running and this is all you hear from 100 feet.

Is it possible that the fan was plugged backwards? Should it push air in or pull the air out? Pulling the air out doesn't seem to make sense with me since it will compete with the fan from inside.

Any help is appreciated.

[Eric S.]

Is there any rattling or is it a pure whirring noise? I ask because there are multiple little flaps in the housing around the fan itself that can get broken off and ingested into the fan and cause a lot of racket.

Another cause of racket is simply a build-up of leaves and debris between the fan and the radiator. About the only way to fix either of these problems is to remove the fan itself and clean everything out.

When I did mine (it had ingested a couple of its own flaps and sounded terrible), it took me about 4 hours, but I work slowly. I followed my Bentley manual's instructions, which required removing the fog lights, headlight trim strips, the bumper, the headlights, and then (finally) the electronic fan itself.

I am 99% certain the fan pushes (or should be pushing) the air front-to-rear.

There is also a nice write-up somewhere (bmwtips.com?) providing tips on troubleshooting that pusher fan.

[nukeduster]

if you ended up with aftermarket fans they can be hellishly loud

we had a supercharged stroked 6.2l hummer with an aftermarket exhaust and its dual electric fans were louder then any other thing on the truck.

[paplip]

Thanks for your reply. The fan is new and it is a BMW. I guess I didn't describe the noise correctly. It is just that the fan is running very fast.

I verified that the fan is actually pushing the air in so what would make it run so fast? It was kind of hot here in the Boston area but didn't think it would have that effect.

I will keep an eye on it and Eric, I found that post on it.

Thanks,
Patrick

[Dirty_Tool]

I have noticed that the newer replacement aux Fans from BMW are noisier than the originals. Also I have noticed that with the current heatwave most e39 aux fans sound like they could be powering an airplane. I would say what you are experiencing is normal for this time of year.