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hissing noise oln e46

23K views 18 replies 14 participants last post by  eerener 
#1 ·
If you guys get a hissing noise from around the intake system on e46 6 cyl bm’s, the problem could be the part arrowed below. That tube thing is usually covered by a rubber cap and if the cap gets broken it will make a hissing noise.
 
#4 ·
I get a high pitched whistling noise that is very hard to catch. It only happens on idle and goes away when i give the car gas. It is very similar to the sound of squeaky breaks and thought it was at first but I didnt have my foot on the brakes at all and figured it wasn't. Ill try to listen for it with the hood open and try to locate it but when I move in for a closer listen I do not hear the sound, it blends it with the rest of the engine noise. It's really annoying. I have no clue where it is coming from.
 
#8 · (Edited)
I had the same thing. I could hear it in the cockpit when I let off the gas and sometimes when I was idling. ( always went away when I pushed on the gas) It gradually got to where it did it all the time enough that I could show it to other people (but never did it when the mechanic looked at it of course) it was like a whistling/moaning/whining kind of sound. It still did it when I turned the vents off, regardless of whether I pushed on the brake, and regardless of whether it was warmed up or not.

i don't know how this could be connected, but I replaced my fuel filter because of several other symptoms my car had (see this thread:http://www.bimmerfest.com/forums/showthread.php?t=428834 ) and everything was fixed and the whistling went away. I know that sounds pretty crazy, but I wonder if the fuel filter is capable of producing that type of sound when it gets clogged and there's not very much space for the gas to push through....worth a try since it's something you gotta do anyway!
 
#5 ·
Hi,

I have the same whistle noise from my 330CI. It goes away as soon as I touch the break pedal or accelerate. It is high pitched "whistle" that's really annoying. BMW garage told me it is a membrane inside the brake booster... I wouldnt mind paying to get it fixed but they did not seem very sure about this so am almost sure I am going to spend money on this with no joy in the end...

Would love to know if you have solved your problem.
 
#6 ·
I have the same brake noise

Hi guys,

I have the same high pitch noise (whistle). I didn't check with the dealer as they charge to just look at the car. Instead, I wend to a local shop and they said it's the brake booster. I haven't changed it yet as it rarely comes on. If anyone did change it please post an update on the result.

Thanks.
 
#7 ·
hi ! I have a 330Xi 2001 and i had this very high pitch hissing sound when i drove my car around and my mechanic found my problem in 2 minutes. It was one of the 2 mass air flow conduit (the one connected to the engine) that had a crack in the small branch going to another hose... the noise was very irritating and my gas mileage was also affected. it took him half hour to replace it and a $28.00 part and everything is beautiful. the car is now quiet and i gain about 1.5l/100km. hope this will help others.
 
#9 ·
Hmmm...didn't see this thread, glad I did.

I have a similar hissing sound and will use some of the ideas here tomorrow to see if I can track it down.

Car is a 2003 330i with 80K.
 
#10 ·
If it is like mine is is when you are driving or idling in park. Anytime you are not pressing the brake pedal. When you have the brakes depressed it goes away. My shop said they thought it was the membrane in the brake booster as someone mentioned earlier. Funny thing is it goes away in colder weather. More of an annoyance than anything else.

Tice03 - the fuel filter at least on my '03 330xi is nearly directly under the driver seat. So if the sound it coming from the engine compartment it's usually cracks in intakes or the brake booster. The reason I think mine is the brake booster is because it stops when I brake. Also the brake booster is a high pitched whistling sound almost like feedback.
 
#11 ·
I have a similar whistle. I hear it whenever the car idles, with or without the brake pedal depressed. The whistle only occurs in warm weather.

I can say definitively that my car's whistle is not caused by a faulty idle control valve, torn intake boot, crankcase ventilation valve or related tubing, or a worn-out DISA valve seal; my mechanic and I have replaced all of these items over the past few years, and the noise persists. In fact, it's louder this year than it's ever been.

:dunno:
 
#18 · (Edited)
I have a similar whistle. I hear it whenever the car idles, with or without the brake pedal depressed. The whistle only occurs in warm weather.

I can say definitively that my car's whistle is not caused by a faulty idle control valve, torn intake boot, crankcase ventilation valve or related tubing, or a worn-out DISA valve seal; my mechanic and I have replaced all of these items over the past few years, and the noise persists. In fact, it's louder this year than it's ever been.
I thought I'd give an update on my car's whistling noise. I haven't heard it in the last three weeks. The sound went away after a weekend in which I replaced the power steering pump, reservoir, and all of the hoses, and put in a new belt-driven fan and fan clutch. A planned replacement of the tensioners, idler pulley, and belts several weeks prior did not make the whistle go away.

The fan clutch and power steering pump were both due for replacement. The fan clutch had begun to engage less frequently in hot weather over the past couple of years. The original LUK LF-20 power steering pump shaft had exhibited some play when I replaced the belts, so I went ahead and upgraded to an LF-30 pump.

I have no idea if this information will help anyone who still hears the whistle, but if you find yourself having to replace a failed power steering pump and/or fan clutch on your own car, you may experience a similar, pleasant surprise.
 
#13 ·
Hissing Noise when in Idle

I just had my mechanic fix this - it was the brake booster. Cost totaled $680 including a complete brake fluid flush (BMW had quoted me $1,200 for the brake booster replacement alone).

Apparently, the brake booster had a leak that made air make the hissing noise when no brake or gas was applied. It only took 1 day to fix and she's now running great, without any annoying noises.

Hope that helps!
 
#15 ·
Between the master cylinder and the firewall. You might be able to detect the leak, but it could be hidden from view. If you removed the vacuum hose going to it and the hissing stopped, it would demonstrate that the booster is leaking. Make sure you plug up the hose while doing this.
 
#19 · (Edited)
tube elbow or the following part could be broken:



http://www.flickr.com/photos/53220531@N03/4913599390/

I recommend replace both of them. If you don't after awhile whistling sound become more annoying and you probably get P0175 code. Basically, the system looses air and in the engine fuel/air ratio become not normal. you probably burn more fuel. the parts are cheap but replacing tube elbow is pain in the bud, the other part is easy to replace.

good luck
 
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