Buzzing sound
Thread Starter
Super Member
Joined: Nov 2008
Posts: 604
Likes: 29
From: SA
2008 C350-Sport-AMG-Active Agility Pack(Not reliable) +Izuzu KB6 3L(It seems Reliable)+Mazda
Buzzing sound
After another trip today of only 34Km's, I parked in garage again, switched engine off. Then I hear this buzzing sound, not the fan that keeps on running for 30min. Open up the bonnet, and yes it's a little Bosch 12V waterpump motor, circulating water beneath the water-bottle, it looks like heater system, te-ed in to main water pype near rediator. After a few minutes it turned off.
Now this seems normal, only thing is I never noticed it before, and it was not hotter than any other day..[9000Km]. Normally after parking car in garage after trips I let it idlle, walk around it, listen for strange sounds and then switch off.
1-Is the buzzing sound normal, or is this motor-pumppy packing up ?
2-What is the real function of this 12V pump, and when should it operate ?
Now this seems normal, only thing is I never noticed it before, and it was not hotter than any other day..[9000Km]. Normally after parking car in garage after trips I let it idlle, walk around it, listen for strange sounds and then switch off.
1-Is the buzzing sound normal, or is this motor-pumppy packing up ?
2-What is the real function of this 12V pump, and when should it operate ?
Last edited by Moto_Guzzi; Jan 17, 2009 at 02:06 PM.
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Joined: Feb 2004
Posts: 3,986
Likes: 6
From: SEATTLE WASHINGTON USA
'08 C300 Lux Barolo Red Beige Leather P2 MM 18" wheels '84 944
Pumping
After another trip today of only 34Km's, I parked in garage again, switched engine off. Then I hear this buzzing sound, not the fan that keeps on running for 30min. Open up the bonnet, and yes it's a little Bosch 12V waterpump motor, circulating water beneath the water-bottle, it looks like heater system, te-ed in to main water pype near rediator. After a few minutes it turned off.
Now this seems normal, only thing is I never noticed it before, and it was not hotter than any other day..[9000Km]. Normally after parking car in garage after trips I let it idlle, walk around it, listen for strange sounds and then switch off.
1-Is the buzzing sound normal, or is this motor-pumppy packing up ?
2-What is the real function of this 12V pump, and when should it operate ?
Now this seems normal, only thing is I never noticed it before, and it was not hotter than any other day..[9000Km]. Normally after parking car in garage after trips I let it idlle, walk around it, listen for strange sounds and then switch off.
1-Is the buzzing sound normal, or is this motor-pumppy packing up ?
2-What is the real function of this 12V pump, and when should it operate ?
As to why it would be running after shutdown, I would ask at the dealer since I can't think of a reason. I have never heard mine running after shutdown.
Thread Starter
Super Member
Joined: Nov 2008
Posts: 604
Likes: 29
From: SA
2008 C350-Sport-AMG-Active Agility Pack(Not reliable) +Izuzu KB6 3L(It seems Reliable)+Mazda
Proved today
If engine running and aircon is on and at coldest setting with aircon running, this motor runs, but if I turn airconditioning off totally, it stops while engine runs.
I did not hear it running today after parking, and engine switched off.
I did not hear it running today after parking, and engine switched off.
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Joined: Nov 2007
Posts: 2,078
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From: NYC
2012 C300 4Matic
Under certain conditions, I believe that pump will remain on for a short period after turning the car off. This is reduce the chances of mold forming on the heater core if the a/c (defroster) has been running and generating water on the fins. The pump also remains on when using REST, but I'm not sure if the w204 has that anymore? This info is based on my W203 knowledge, but probably applies to the w204 since they are so similar.
