Rattle

T

tiggy1985

Member
Hi All,

I hope you can help. I have been a member for a very short time and have found the forum very helpful so far!

As I have not introduced myself yet I shall do so now. My name is Luke and I live in East Yorkshire. I drive a 2.5Ltr 05 plate Z4 SE which I have owned since March this year.

I have been unlucky enough to have a few problems since buying the car with full BMW service history, infact its in the garage now having the roof motor replaced!!! :!:

The new problem is this... When I accelerate there is a rattle noise that seems to come from underneath the car. This happens usually at around 2000-2500 RPM and there seems to be no rhym or reason as to when it happens. The garage have had the car back twice now and have said that they can not find anything. They have tightened all of the exhaust brackets and bolts and have said they cant find anything else. The noise is there and is getting worse.

Any ideas anyone?

Cheers

Luke
 
Welcome Luke,

Have you checked your rear springs? they break easily and the broken pieces could be rattling around with the vibration
 
Sounds obvious but have you taken the 'garage' out in the car and demonstrated the rattle? Could be baffles working their way loose in the exhaust back box - just a thought.

http://bmwfans.info/parts/catalog/E85/Roadster/Europe/Z4_2.5i-N52/RHD/N/2005/august/browse/exhaust_system/exhaust_system_rear/
 
Hmm specific revs can greate different acoustics and a certain tone is reached which could cause the baffles to vibrite then ( lol listen to me eh, for a moment there it sounded like i knew what i was talking about)
 
Thanks for the info. I have taken one of the technician's with me but he and many of his colleagues are stumped... Not sure what to do next?

I have read on the forum something about a value in the engine that can come loose and vibrate. Does anyone know what I am talking about?
 
Does your car have a Sound Generator fitted? Mine caused a Buzz/Rattle at certain RPM's which took me bloody ages to fathom as the noise sounded all around!

Does it usually happen at the same rpm then or intermittently? Car Hot/Cold/Both?

Try to see if it does it while stood still, get a mate to vary the throttle around those RPM and prod/poke everything you can see till it stops! :)
 
Not sure Ed. If it has how would I know? The weird thing is that the noise never happens when the car is still. You can rev its arse off and still no rattle...
 
I think i have exactly the same issue. To me it sounds like a loose heatshield vibration/buzz noise. I had the exact same problem on my old Fiesta RS Turbo years ago. It used to happen on that car around 2500rpm when it came on boost then go 2 secs later. It turned out to be a broken bolt that screwed into the exhaust manifold which allowed the heatshield to vibrate/buzz. On my Z4 it starts around 1800rpm then stops just after 2000. This is while on the move. I asked the main dealer to look at the exhaust heatshield while it was in a while back but they said everything was ok and they couldn't find anything wrong :(

I never thought of checking the sound generator so will try that next.
 
Yes thats the same as mine. Like you I have asked my garage (who supposedly specialise in high performace cars) to look at it and they can not find it either.... Very strange. Were is the sound generator so I can check it aswell please ?
 
chrismann85 said:
Welcome Luke,

Have you checked your rear springs? they break easily and the broken pieces could be rattling around with the vibration
Click to expand...

Yes I have checked the springs Chris. Infact one was replaced when the car was MOT'd prior to me collecting it. :?
 
I had the same problem and just had it diagnosed and repaired. Your DISA valve is failing. Since it is controlled by vacuum and rpm's that is why the noise comes only in a specific rpm range while accelerating. The part is about $230 and it may require reprogramming the computer.
 
Not what I was wanting but thanks for the answers guys. Looks like another expensive repair for the Z4! Honestly this car has cost me £1600.00 in repairs since March! Its a good job I bloody love the thing!!! :poke:
 
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