[spitfire9200]

Hey guys,

When I start my car up for the first time in awhile (cold start), I hear a slight rattle that lasts for about 2-3 seconds as the revs drop initially to idle.. Sounds like something opening/closing. It is not the exhaust port (it's been disconnected), It is definitely coming from the engine bay, and ONLY when the car is cold. It's kind of bothering me. Once the car is started again it won't happen until it sits for awhile. The dealer has my car right now and said it's normal, but I haven't picked it up yet.


I may be paranoid, but I want to know. I can take a video if necessary.

Thanks!

Car is a 2009 335i coupe/auto.

[jdbretz]

Sounds like your wastegates may be rattling a little. Do you ever notice it when you are accelerating and let off the gas? I wouldn't call it normal but it is a common "issue" with the N54. It isn't something to really worry about causing damage, but I hear its rather annoying. If you keep pressing your dealer about it you may be able to get your turbos replaced.

[spitfire9200]

Originally Posted by jdbretz

Sounds like your wastegates may be rattling a little. Do you ever notice it when you are accelerating and let off the gas? I wouldn't call it normal but it is a common "issue" with the N54. It isn't something to really worry about causing damage, but I hear its rather annoying. If you keep pressing your dealer about it you may be able to get your turbos replaced.

Really? Such a short rattle only on a cold start? Also I thought the 09 doesn't have waste gate problem and the rattle comes from the bottom of the car or the exhaust area

[spitfire9200]

Only rattles 2-3 seconds as well

[TiAg335i]

Does it happen when you do a slow takeoff from stop?

[spitfire9200]

Originally Posted by TiAg335i

Does it happen when you do a slow takeoff from stop?

Nope.. Just on the initial start up

[TiAg335i]

Originally Posted by spitfire9200

Nope.. Just on the initial start up

Probably the exhaust or wastegates. Just a guess though. More likely wastegates.

Does it make the sound when you rev?

[Jeff@TopGearSolutions]

or exhaust flap.

[TiAg335i]

Originally Posted by Jeff@topgearsolutions

or exhaust flap.

He said he disabled it thru the plug.

[Jeff@TopGearSolutions]

Originally Posted by TiAg335i

He said he disabled it thru the plug.

IT can still rattle disabled... its loosey goosey.

In this case its probably wastegates.

[Alan l.]

Mine does the same thing on cold starts. Not all the time and my wastgates don't rattle at all when I'm driving. Just occasional cold starts. I just consider it normal for this car along with a lot of other things.

Alan

[cstmx_ryder]

If it is the wastegates, can you replace them just by themselves? Meaning, not having to buy the whole turbo assembly?

[spitfire9200]

Originally Posted by TiAg335i

Probably the exhaust or wastegates. Just a guess though. More likely wastegates.

Does it make the sound when you rev?

Originally Posted by Jeff@topgearsolutions

or exhaust flap.

Originally Posted by Alan l.

Mine does the same thing on cold starts. Not all the time and my wastgates don't rattle at all when I'm driving. Just occasional cold starts. I just consider it normal for this car along with a lot of other things.

Alan

no sound when I rev.

And my exhaust was disconnected, and then replaced. def not exhaust

[spitfire9200]

Originally Posted by Alan l.

Mine does the same thing on cold starts. Not all the time and my wastgates don't rattle at all when I'm driving. Just occasional cold starts. I just consider it normal for this car along with a lot of other things.

Alan

what year is your 335? Yeah it's a short rattle when it revs up, then 2-3 seconds later it's gone when the rpms stable out. I get no noise driving either

[TiAg335i]

Wouldn't worry about it

[Alan l.]

Mine is an 09, July build.

I haven't noticed mine doing it as of late but i've heard it before. Only lasts for at most 1-2 seconds and its gone. Happens right when i hit the start button.

Alan

[spitfire9200]

Originally Posted by Alan l.

Mine is an 09, July build.

I haven't noticed mine doing it as of late but i've heard it before. Only lasts for at most 1-2 seconds and its gone. Happens right when i hit the start button.

Alan

sounds pretty much what I'm experiencing and I have the same year.

did you ever take it in or look into it?

[drew4392]

same here. like a metallic rattle or something immediately at start up. only lasts a couple of seconds. This has always occurred-- from the first day I bought it as a CPO. They put the CPOs through the ringer, so if it was a problem, it would have been identified as such way back when.

I dont think its something to worry about.

[Bakeme521]

def. the wastegates mine always do it when they are cold. Even did it when I got them replaced with new ones when they were cold.

[335i-boy]

Mine has been doing exact the same thing the last couple of months. Like the OP, for 2-3 seconds on cold start up. ie first thing in the morning.

Service tech at the dealer says its the exhaust flap, but I can hear it coming from the front of the car, not the rear. Took it back and they tell me its the exhaust flap.. again. I thought my sense of hearing was failing me, it is quite clearly coming from the engine bay.

Had turbos replaced at 12,000 miles for the dreaded siren noise. I did not hear any rattle type noise before then. Have done 5000 miles since new turbos were installed. This rattle has just started a couple of months ago. Freakin' hate it!! Hope it does turn out to be wastegates. Just would love to know what it is.

[domrep]

rev the engine to about 2.5-3 and let the engine drop, if you hear the same sound it should be the WG

[Alan l.]

Originally Posted by spitfire9200

sounds pretty much what I'm experiencing and I have the same year.

did you ever take it in or look into it?

Never brought it in since its so minor and seems to be normal with this car. doesn't do it all the time and i never hear it while driving so its fine by me.