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      04-06-2011, 04:49 AM   #1
lve2xlr8
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Drives: '11 m3
Join Date: Aug 2008
Location: Los Angeles

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Post M3 Noises (What's Normal/Not Normal)

Okay I'm going to try and summarize all the data from this thread for quick reference.

Normal:
  • Cold/Initial engine start sounds like leaking exhaust manifold. This is the dme leaning out the cats to heat them up quicker. Goes away after a couple minutes or depending on how cold the cats are.
  • After engine warmed up sounds like exhaust manifold leak at low rpm, especially with heavier throttle. This is just the way a high revving v8 with awesome factory headers sounds down low. You'll learn to love it after you realize there's nothing wrong with the car.
  • Pump noise near driver's door jam when first starting off sometimes. This is a brake vacuum pump (or something like that). It's normal. If it comes on frequently during your drive and stays on a while, there's a sensor that probably needs to be replaced (this happened to me).
  • Clunking coming from underneath the car (DCT). This is what a DCT sounds like, especially when you're shifting between D & R. Again, you'll learn to love it.
  • Whine coming from rear of the car at certain speeds. This is differential whine and it's normal. I hear mine from about 25-35mph always.
  • Sizzling coming from front of the car after turning it off. This is condensation coming from your a/c dripping on hot exhaust parts.
  • Intake resonance around 4k rpm. This became very pronounced after I added my Akra Evo exhaust system. So pronounced,in fact, that I reinstalled my factory air filter to eliminate some of it. RPM where this occurs depends on which exhaust or air intake/filter you have.
  • Fan runs after engine shut off. This will happen when you run the car hard or it's really hot and then you turn it off. It's normal, let it do its thing.

Not Normal:
  • Clicking coming from rear differential while making tight turn. Although this is common, it's not normal. Take it in and they'll put it an additive. Mine was eliminated afterwards. Whine still present though (normal).
  • Cow bell noise. Rocks stuck in your rotor heat shield.

I will continue working on this, but that's all the time I have for today.

If you know of a noise, and what it is (or you don't,) post here!
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'11 M3
'00 M5 - Sold

Last edited by lve2xlr8; 04-17-2015 at 09:34 PM.