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-   -   Possible Aux Fan Switch Failure? (https://xoutpost.com/bmw-sav-forums/x5-e53-forum/100211-possible-aux-fan-switch-failure.html)

wagner.a.charles 03-27-2015 07:40 AM

Also, running the AC at full blast makes no difference.

LVP 03-27-2015 08:05 AM

Quote:

Originally Posted by wagner.a.charles (Post 1032260)
Also, running the AC at full blast makes no difference.

Makes no difference as in it does exactly the same thing when you turn on the AC? That seems really loud. Is it really the fan? I know the camera mic probably makes it sound worse.

wagner.a.charles 03-27-2015 08:09 AM

Sorry, I meant that when I turn the AC on, the fan doesn't go haywire. Yeah, it's pretty loud. That's why I wanted to get a video. It's not the typical "warming up" kind of sound. It SEEMS like it's the fan, but it's hard to tell. It only does this in the morning when the engine is cold and when I leave for work, it's dark outside. Honestly though, the fan didn't seem to be spinning out of control or anything. I'm open to other possibilities haha!

g300d 03-27-2015 08:16 AM

It looks like it is going on high speed as it should, but it doesn't sound right I agree.

Mine does that on start up but sounds different, you hear the wind roar more than the fan motor.

Sounds like a worn bearing or something in the rotating assembly.

upallnight 03-27-2015 08:18 AM

Quote:

Originally Posted by wagner.a.charles (Post 1032259)
Grabbed a video this morning so y'all could hear it. https://youtu.be/u10F4lYYRSA

The fan that you are video taping is not the Aux fan. That fan is the fan attached to the engine water pump.

The Aux fan is in Front of the radiator. If the noise is coming from the fan that you are taping, could be a bad bearing in one of the idler pulley or a bad tensioner. Worse case scenario is that the bearing in the water pump is shot.

g300d 03-27-2015 08:24 AM

Just saw your post where you said it doesn't sound that way at Max AC.

I think it's the secondary air pump trying to pump against a stuck closed secondary air injection valve.

See that silver mushroom sprouting from the left front of the cylinder head? That's the secondary air injection valve. There is a black hose from there going to the secondary air pump. It activates on cold starts only.

Disconnect the black hose from the valve before the next cold start and see if the sound changes.

Is your CEL lit?

wagner.a.charles 03-27-2015 08:29 AM

Hmm I want to say that I replaced the fan clutch a few months ago when I was replacing the alternator. I don't remember seeing anything funky with the tensioner, but that doesn't mean anything. How would I go about testing those things? Maybe seeing it in the daylight will be a good start ��

wagner.a.charles 03-27-2015 08:31 AM

Quote:

Originally Posted by g300d (Post 1032270)
Just saw your post where you said it doesn't sound that way at Max AC.

I think it's the secondary air pump trying to pump against a stuck closed secondary air injection valve.

See that silver mushroom sprouting from the left front of the cylinder head? That's the secondary air injection valve. There is a black hose from there going to the secondary air pump. It activates on cold starts only.

Disconnect the black hose from the valve before the next cold start and see if the sound changes.

Is your CEL lit?

Nope, it's not on. Went off when I replaced the throttle boot :)

g300d 03-27-2015 09:41 AM

Well, remove the hose to the valve anyway, a failing secondary air pump is also known to get pretty noisy, and those pumps only turn on at cold starts.

I remember that sound from when I had to diagnose my own secondary air injection system...sounds very familiar.


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