# 335d weird sound



## TD328 (Sep 22, 2008)

I have noticed a weird sound coming from the back of the car lasting for about 30'secs after I have turned my car off. Initially I thought was my electric garage but lately I payed more atention. In a scale 1 to 10, is about a 4. It is hard to located but it looks it is coming from the rear. Sounds like a small blender, last 30'secs and then a click like sound
And then nothing....

Anybody has experience this? Any ideas what this my be?

Car is running great!!!!!

Thx


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## cssnms (Jan 24, 2011)

common question, it's normal


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## KeithS (Dec 30, 2001)

Believe it's the DEF transfer pump (moving fluid from the passive to active tank). I've never noticed that in particular, the car seems to make all sorts of electric motor noises all the time.


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## wanderlust (Feb 19, 2012)

the gerbal that turns the engine is off his wheel and trying to escape...

powered by lemings


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## Flyingman (Sep 13, 2009)

It is either the DEF Transfer or the Fuel.

There is also some fan that may be heard after you shutdown the car. It is not the DPF fan under the hood, this sounds like it is inside the car, perhaps related to the AC and Ventilation? Not sure.

The DPF fan sounds like one of those electric radiator fans that stays on for a few minutes after you shurdown. You will note a lot of hot air being blown out from around the engine compartment.

I wouldn't worry about it.


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## János (Jun 19, 2010)

If it is from the trunk area then it is probably the DEF transfer pump. I often hear it whirring after I park and am unloading the trunk.

The other unusual noise I've heard (mentioned here a few times) is the engine whine that occurs every time I hit 70mph. It goes away when I go slightly faster or slower.

I've also noticed some creaking and bumping noises coming from behind the dashboard after I shut off the engine. I'm thinking it has something to do with the climate control.

Sometimes I hear what seems to be a pump running as soon as I unlock the doors (before starting the car).

Lots of interesting noises.


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## railroader (Apr 12, 2010)

János said:


> Lots of interesting noises.


True that! I also notice that if you open the hood on the 
335d, no matter the temp. of the engine, there can be an 
amazing number of various odd relays clicking open or closed...
These clicks come from all corners of the engine bay to my ears..

My Service Advisor said recently that there were about 60 different
"computers" (his word) that talk to each other in this car. Maybe not
computers, per se, but more likely RELAYS that clack open and closed
for one reason or another...

Complex car it is!


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## dnaer (Jan 13, 2011)

When I turn off my car, I see dead people. Never mind, its just my wife telling me to fire up the grill.


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## TD328 (Sep 22, 2008)

Thanks ya all for your replies!!!


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## Snipe656 (Oct 22, 2009)

I think you are hearing the soot blender that engages before the soot is burned off.


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