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Go Back   Bimmerfest - BMW Forums > BMW Model Discussions > 5 Series > E39 (1997 - 2003)

E39 (1997 - 2003)
The BMW 5-Series (E39 chassis) was introduced in the United States as a 1997 model year car and lasted until the 2004 when the E60 chassis was released. The United States saw several variations including the 525i, 528i, 530i and 540i. -- View the E39 Wiki

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  #1  
Old 07-30-2011, 10:26 AM
Alabama John Alabama John is offline
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Location: Pinson, Alabama
 
Join Date: Jul 2010
Posts: 75
Mein Auto: E39 97 540I
Exhaust noise

In my 97 540I there is something right before the muffler in the rear that is the same size as the muffler and the exhaust goes into it but it doesn't have an exit. It must roam around and then exit.

The exhaust then go into the muffler and out the backside of the muffler to the outside.

There is also in the exhaust piping about under the back seat area underneath the car another piece, not as big as the one next to the muffler that exhaust also goes into with no exit and then continues on the exhaust piping toward the rear to the one I just mentioned that is next to and before the muffler.

Question? what is that thing and can both dead end things be cut off and straight exhaust go from the catalytic converters to the muffler in the back without those deadending things?
What problems would that cause if any?

Thanks,

John
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  #2  
Old 07-30-2011, 04:15 PM
Alabama John Alabama John is offline
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Location: Pinson, Alabama
 
Join Date: Jul 2010
Posts: 75
Mein Auto: E39 97 540I
Its a resonator.

There is another one up front somewhere.
Someone sent me lots of info of folks taking them off and still using the stock muffler or changing it to some other, like a Remus muffler .
Anyone here done this and did it cause you any problems?
If not, I'm doing it next week and continuing using the stock muffler (for now).

Anyone done this I can ask a few questions?

Cost about $100.00

Why has no mechanic or BMW dealer advised this?
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  #3  
Old 07-30-2011, 07:51 PM
edjack edjack is online now
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Location: San Jose, CA
 
Join Date: May 2007
Posts: 8,843
Mein Auto: '97 540i 6 speed
BMW went to great lengths to design an exhaust system that would properly extract the gases, and make minimal noise. Why does everyone want to redesign this system?

There is a "silencer" inside the cats, a Y-shaped "resonator" further downstream (which allows for a dual exhaust on the E38), and a Helmholz resonator next to the rear muffler to smooth out the exhaust flow.

You modify this system at your own risk. Unless your only aim is to make more noise, and not improve performance, do a before/after dyno run to see what the effect is. You'll no doubt find little performance improvement.
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  #4  
Old 07-30-2011, 08:21 PM
Alabama John Alabama John is offline
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Location: Pinson, Alabama
 
Join Date: Jul 2010
Posts: 75
Mein Auto: E39 97 540I
I have had a noise when I apply throttle when cruising that is loud and growling. I've changed out so much trying to find it and spent thousands.
Had it at yet another BMW mechanics yesterday and he rode and listened and said he in all his years working on BMW's had never heard any thing like it. Give it more gas and it stops, let off gas and it stops. Can't make it do it downhill, only uphill or level.
He beat with a rubber handle in my exhaust and said the resonator was broken inside some way,as it rattled. The one next to the muffler.
I had it removed today and the noise is not near as often and not near as loud nor maddening. Now I hear it only underneath where the other one is instead of all the way from middle of car to the rear.
So far, its not running any louder.
I want to remove the closer to the middle one too as it must also be bad.
Read there was a Dynomax 2-1/2 inch Bullet Resonator for $38.00 that would return backflow when installed where the forward resonator was.
I didn't know resonators went bad or what one was but if it stops the loud roaring noise I'm all for it. We have had enough turning up the radio louder and louder as it gets worse over time.

Thank you for your comments. I appreciate all advice!
I would likwe it to run quiet, I'm not after more sound of any kind.
Any Ideas are welcomed.
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  #5  
Old 07-30-2011, 08:29 PM
98540iA 98540iA is offline
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Location: Rocky Mountains
 
Join Date: Nov 2010
Posts: 332
Mein Auto: '98 BMW 540iA (born 9/97)
I put a bullet resonator where the big y shaped boomerang resonator was and a 40 series Flowmaster muffler in place of the stock mufflers. Sounds beastly down low and just a bit louder than stock at higher rpm's. Feels like I gained a nice bit of low/mid range power with this setup too. If I were you I'd do what I did but with stock muffler or a new quiet muffler.
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  #6  
Old 08-05-2011, 11:54 AM
Alabama John Alabama John is offline
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Location: Pinson, Alabama
 
Join Date: Jul 2010
Posts: 75
Mein Auto: E39 97 540I
Thanks 98,

I just put the 23 1/2 inch bullet resonator or straight muffler, whatever it s called, on. Had to find an electric welding outfit as so close to gas tanks made me nervous. cost Cost about $20.00 more than the 16 1/2 inch but should be quieter.

Helped a lot, not too loud with stock muffler. Seems to run better too.

Thanks again!
John
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  #7  
Old 08-05-2011, 09:42 PM
qwksilver97 qwksilver97 is offline
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Location: Cape Coral, Florida
 
Join Date: May 2009
Posts: 78
Mein Auto: 1997 540ia
Is your growling noise gone? I have the same problem its very hard to diagnose.
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  #8  
Old 08-06-2011, 04:43 AM
Alabama John Alabama John is offline
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Location: Pinson, Alabama
 
Join Date: Jul 2010
Posts: 75
Mein Auto: E39 97 540I
It is only about 20% as often as it was. Same loudness but not doing it at all in many places around home where it always did.
It sure makes me believe it has something to do with the exhaust.
I kept the same muffler and have almost 180,000 miles on it and the 2 pieces I took off.
Car sure has more pickup. Only sounds loud inside vehicle at low speeds. Not loud outside, just deeper. Can't hear it at all at highway speeds neither inside or outside.
Cheapest thing I have done too.

98 knew what he (she) was talking about.

Last edited by Alabama John; 08-06-2011 at 04:47 AM. Reason: left something out
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