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E46 (1999 - 2006)
The fourth generation 3 Series (E46 chassis) was introduced in 1999 and set the standard for engineering and performance during it's years of production including being named to Car & Driver's 10 best list every one of those years! ! -- View the E46 Wiki

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  #1  
Old 09-04-2007, 05:39 PM
b027 b027 is offline
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engine rattle from front at idle - help on diagnosis

Hi everyone, I've got an engine sound on my 2002 330i that I'd like opinions on. I've searched the e46 forum but not found something that really sounds like my problem.

The engine makes a relatively loud (clearly audible), slow, rough rattle. The sound is most noticeable at idle, and can best be heard by listening from the front air intake with the hood down. It's not so obvious with the hood up when the rest of the engine can be heard more loudly. It's hard to describe more clearly, but I can probably attach an audio recording if it would help.

When I first got the car (4K miles ago), the sound was only there on startup, and it went away as the engine wamed up. Now the sound is there even after the engine warms up, so it seems to be getting worse. I live in a warm climate and it has not been cold. Also, turning the A/C on or off has no effect. I'm pretty sure its not the vanos, which from another thread (with attached video recording) I understand to be a rapid rattling sound.

Any suggestions? I'm taking the car to my mechanic soon for local advice, but would still like to know if anyone recognizes or has had these symptoms.

Thank you!!
Brian
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  #2  
Old 09-04-2007, 05:47 PM
cliffbmw cliffbmw is offline
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I have a 2003 325I and think I have the same problem.
Let me know what you find, I plan on having my car in for service in the next couple of months but if its really bad I was to take care of it now.
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  #3  
Old 09-04-2007, 05:53 PM
b027 b027 is offline
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Cliff, I'll be sure to post what I find.

How long has yours been making the noise? Has it gotten worse over time as I described?
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  #4  
Old 09-04-2007, 07:04 PM
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crowz crowz is offline
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Main bearing or rod?
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  #5  
Old 09-05-2007, 05:59 PM
cliffbmw cliffbmw is offline
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it hasn't gotten any worse, but it has not gone away either.
It really only happens at when at ide or under 10-15 MPH.
once I start drving it goes away.
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  #6  
Old 09-06-2007, 07:04 PM
FalconGuy FalconGuy is offline
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I will bet my unborn son its the Idler pulley or tensioner

Take a tip, when the car is idling and the noise present, take a small amount of water, remember the alternator is below the idler pulley, spray each pulley one by one. When the noise stops you found your culprit

Realoem.com for great expanded diagrams and part numbers.

If its happening with the AC on, Only, then I would jump to that tensioner

Make sure you look to see what type you have before you order, by production date my was to have the mechanical, so I ordered one ( still have it) after getting in deep I discovered I had the hydraulic type. Supposedly better but its failed 3 times, the mechanical never really failed, just a start up squeal

Email me if you need help, been through this a lot. If your noise goes away after some power is added, the belts are now loaded, no need for a tensioner that is why I am pretty sure by your description that is the culprit. The belts are 15 bucks each, Idler pulley maybe 40 bucks, tensioner another 50. You can do this yourself for sure.
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  #7  
Old 09-06-2007, 07:39 PM
c0mikal c0mikal is offline
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i have a rattling noise too, its noticable if i turn off my car. and it sounds like a fan dying down hitting metal. but not as tough, it was like that since it was brand new, i have a e90. any suggestions?

Last edited by c0mikal; 09-06-2007 at 07:45 PM.
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  #8  
Old 09-07-2007, 03:52 AM
gesoffen gesoffen is online now
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I'll bet Falcon's unborn son that he is right. Typical symptoms for a idler or tensioner going south. However, you describe it as a rattle but most describe it as almost a growl. Eitherway, it usually disappears at off-idle speeds and also after the engine/tensioner is warmed up. You indicate that has developed into a sound that won't disappear as the engine warms. Your tensioner/idler may be on its last legs.

You don't mention milage but I'd consider replacing all tensioners/idlers and the two belts as PM. May as well do a water pump replacement and coolant drain//fill while you're in there. FYI, all these tasks are easy DIYs with no special tools required (save for the Bentley manual).

BTW, I'd do this ASAP. If your idler/tensioner seizes or fails, you'll shred the belt in short order. If it happens to be the PS/water pump belt, you'll lose steering boost and you could end up overheating the engine.
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Last edited by gesoffen; 09-07-2007 at 03:56 AM.
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  #9  
Old 09-07-2007, 06:23 AM
b027 b027 is offline
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Falcon and gesoffen,

Your suggestions make a lot of sense. Falcon, thanks for the offer to help.

I got under the hood this AM with a spray bottle and tried to hit the different pulleys. (It wasn't easy to do from the top, as I thought I was mostly spraying the pulleys edge on and not hitting the bearing area. Any tips on doing this?) In any case, I didn't notice any perceptible difference upon spraying, but I might not have hit them well enough to change anything...?

I did notice though that the fan blades (when at rest!) have significant lateral play - I can move the fan about 3 mm from front-to-back at the outside edge. Should it be this loose? Could the fan coupling be causing the noise? Closer examination reveals that the coupler is definitely moving while the nut attached to the water pump remains still.

Also, I saw that the upper pulley/tensioner base is shiny and new looking - so I suspect it was replaced recently before I bought the car (I've only owned it for 5K miles, and its at 74K now). I couldn't see the lower pulley.

I'm thinking of replacing the fan coupling (part # 11527505302) due to the observed play. As gesoffen suggests, I may also do the water pump, belts, lower idler pulley, and coolant change while I'm in there, just to be safe.

Do you folks agree?

Thanks!!

Last edited by b027; 09-07-2007 at 06:30 AM.
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  #10  
Old 09-07-2007, 07:12 AM
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KrisL KrisL is offline
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I agree - and I'd also do the thermostat and hoses while you're in there.
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  #11  
Old 09-07-2007, 10:38 AM
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boriska00 boriska00 is offline
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I have this same low pitch growl/rattle when i start up the car and it sits at idle. As soon as a little power is added, the noise goes away.

Mine is '01 330i with 130k on it. All belts were replaced around 80k, but everything else there is original..

b027: Did you figure out anything about the fan? Is that play you're talking about normal?
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  #12  
Old 09-09-2007, 05:45 PM
FalconGuy FalconGuy is offline
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Agree 100%

I would though try to hit the bearing surfaces with the spray, that's where the failure occurs. I would not hesitate to pour a tiny amount on each, if it makes you feel better jack up the side with the alternator ( Drivers side) so the water would run downhill and away.


Then again, lets face it, this stuff is either failed or will fail, the labor is not bad if you do it all at once, if its coming out, and you can put a new one in for 50 bucks, its a no brainer. Waterpump, pulleys, belts. I ended up replacing my fan and fan clutch when I lost it years ago one night with the insane clearance, it was cheap and it gave me some comic relief at the time

Autohauz best deals on parts for me

I wasn't kidding about my unborn, yesterday was the baby shower or I would have responded sooner


Good luck, dont hesitate to ask for pics
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  #13  
Old 09-09-2007, 07:46 PM
Drivewfo Drivewfo is offline
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Mine made a similar noise, but it was the alternator.
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  #14  
Old 04-03-2008, 01:07 PM
b027 b027 is offline
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Solved!

It's been a while since my original post, but I solved the problem and wanted to report back for anyone else facing the same or a similar issue: replacing the fan clutch solved the problem and the noise went away completely. The new clutch was $95 from Autohausaz, and I also spent $40 for a water pump pully holder and 32mm thin wrench combo from ZD Mack tools (the tools are a good investment for future work too).

Looking back, I am still amazed that the old clutch could make that much noise - it was really quite loud and the engine just sounded terrible. It was most noticable through the front grill.

The lateral play I observed at the edge of the fan blades was about 5 mm, but the fan didn't seem to move freely enough (laterally; not rotationally) to make the relatively loud "marbles in a tin can" type noise that I was hearing.

While I was in there, I did replace the belts. The water pump and idler pulley were replaced only 15K miles ago and appeared to be in good condition, so I left them alone for the moment.

Thanks for all the advice!
Brian
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  #15  
Old 04-09-2008, 10:18 AM
tallboy2023 tallboy2023 is offline
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I had the same issue.... replaced the idler pulley and no more noise
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  #16  
Old 04-09-2008, 05:31 PM
DM3MD DM3MD is offline
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Quote:
Originally Posted by tallboy2023 View Post
I had the same issue.... replaced the idler pulley and no more noise
Same here...replaced the idler pulley and the "chatter" went away.
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