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7 Series - E38 (1995 - 2001)

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  #1  
Old 07-04-2013, 12:54 AM
Jon740 Jon740 is offline
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Mein Auto: 2000 740i
Weird humming

I just Baught a 2000 e38 and have a humming issue coming from the engine either when I start the car or after a period of driving over 70mph new to this world it's my first car. ANY! Suggestions is helpful...


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  #2  
Old 07-04-2013, 09:33 PM
Mayorchuck Mayorchuck is offline
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Can you make a video with the hood up when it's making the noise after start?
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  #3  
Old 07-05-2013, 09:00 AM
Jon740 Jon740 is offline
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Mein Auto: 2000 740i
Weird humming

Yes I can


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  #4  
Old 07-14-2013, 06:29 PM
Podmore Podmore is offline
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Quote:
Originally Posted by Jon740 View Post
I just Baught a 2000 e38 and have a humming issue coming from the engine either when I start the car or after a period of driving over 70mph new to this world it's my first car. ANY! Suggestions is helpful...


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Check the viscous coupling on the fan (designed to engage at low engine speeds to pull extra air through the radiator) - you should be able to stop the fan with a rolled-up newspaper at idle. If you are unable to stop it, that may be causing higher than normal fan noise (and if so, replace the fan clutch immediately as they are not supposed to run a full engine speed and have been known to fire fan blades up through the bonnet (hood)).

There is also the additional thermostatic fan which sits in front of the a/c condensor which is electrically powered and should come on when ambient temperatures are high and the engine is running hot and at low speed. When this cuts it it emits quite a loud humming noise.

Other than that, any part which is spinning when the engine is running (alternator, water pump, power steering pump, a/c compressor, idler/tensioner pulleys) may emit a humming noise if they are suffering from a failing bearing.
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  #5  
Old 07-14-2013, 09:44 PM
Sobek Sobek is offline
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Location: Queensland, Australia
 
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Mein Auto: 1996 BMW 730iL
I'd also just like to throw it out there that a bad PCV membrane can cause a sound just like a humm when heard from within the car. Usually there's a slight tear in the membrane and the air zips through causing the tear to flap, which when contained within the membrane housing results in a sort of 'humm' sound. Pretty easy to tell - when it's making the sound, just reach down the back of the intake manifold and press firmly against the membrane housing on the back of the PCV. If it's humming, you'll feel it and most likely cause the sound to alter when you press down.

Just a thought, could be as simple as that.
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  #6  
Old 07-15-2013, 01:22 AM
Jon740 Jon740 is offline
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Mein Auto: 2000 740i
Weird humming

Thanks you guys ill have my mechanic check it out ASAP and get back to you


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