e36 325i Irritating rattle

[bmwfanboy]

o.k. So i got this weird rattle sound at certain rpms.

It will only make the sound just before it shifts at about 2500 to 3000 rpms. Now i thought maybe vanos, but it was redone a couple of months ago.

A friend told me his car did exactly the same, and discovered that at certain rpms the engine vibrates a bit. This caused the spring on the flange where the exhaust enters the manifold to rattle, and this caused the sound.

Now i haven't checked it yet, but can it really be something so simple. The solution; tighten the bolt on the spring!!

Like i said my weird rattle sound only appears between those rpms just before or after it has shifted. Any revs higher or lower than that, and it's dead quiet.

Any input from the experts would be greatly appreciated. Thanks

 

[freerider]

Vibration damper maybe?

 

[bmwfanboy]

Vibration damper maybe?

Wow. That was a quick reply. Thanks.

A vibration damper? Sorry i am a bit new to anything mechanical, where is it located and what does it look like?

 

[freerider]

Let me see if I can find a diagram..


ok this is the part, number 1 in the diagram
http://www.realoem.com/bmw/showparts.do?model=CB42&mospid=47444&btnr=11_0335&hg=11&fg=18

Have you had the exhaust checked out though? might be baffles or something like that

 

[bmwfanboy]

Thanks,

now how hard is it to replace the vibration damper? Is it a huge job?

Luckily we got a local bmw mechanic that's really good.
He use to be the head technician at the local stealership, but then opened his own place.

 

[freerider]

I would look at other options before you go and shell out cash for a vibration damper, it will probably cost about R4k from the dealer.

Take your car to the mechie and see if he cant diagnose that rattle for you.

 

[Raybimmer]

:clap:
Hi is the noise there only when driving ? If it is only there when driving it could also be a loose/breaking gearbox mounting etc - these vibrations can cause noise at different frequencies which we hear at certain revs/min or road speeds .
Is the noise there if the car is hot or cold ?
Because bms are normally quite we notice noises that would not be heard in other cars.
Cheers
Raybimmer

o.k. So i got this weird rattle sound at certain rpms.

It will only make the sound just before it shifts at about 2500 to 3000 rpms. Now i thought maybe vanos, but it was redone a couple of months ago.

A friend told me his car did exactly the same, and discovered that at certain rpms the engine vibrates a bit. This caused the spring on the flange where the exhaust enters the manifold to rattle, and this caused the sound.

Now i haven't checked it yet, but can it really be something so simple. The solution; tighten the bolt on the spring!!

Like i said my weird rattle sound only appears between those rpms just before or after it has shifted. Any revs higher or lower than that, and it's dead quiet.

Any input from the experts would be greatly appreciated. Thanks

 

[SlowMo]

Electronic wastegate rattle maybe?

Have you had the exhaust checked out though? might be baffles or something like that

+1 to this. I'm almost certain its exhaust related, from anything like a broken rubber to a loose heatshield...around that rev the exhaust system has the highest resonance, so would make sense that its quiet all the other times in the rev range. Have it checked out, usually free to do so as well.

 

[bmwfanboy]

:clap:
Hi is the noise there only when driving ? If it is only there when driving it could also be a loose/breaking gearbox mounting etc - these vibrations can cause noise at different frequencies which we hear at certain revs/min or road speeds .
Is the noise there if the car is hot or cold ?
Because bms are normally quite we notice noises that would not be heard in other cars.
Cheers
Raybimmer

o.k. So i got this weird rattle sound at certain rpms.

It will only make the sound just before it shifts at about 2500 to 3000 rpms. Now i thought maybe vanos, but it was redone a couple of months ago.

A friend told me his car did exactly the same, and discovered that at certain rpms the engine vibrates a bit. This caused the spring on the flange where the exhaust enters the manifold to rattle, and this caused the sound.

Now i haven't checked it yet, but can it really be something so simple. The solution; tighten the bolt on the spring!!

Like i said my weird rattle sound only appears between those rpms just before or after it has shifted. Any revs higher or lower than that, and it's dead quiet.

Any input from the experts would be greatly appreciated. Thanks

Hey Ray, funny you should ask. I noticed it only does it when the car is
getting hot, in the mornings when it is still getting to temperature, the sound is not there. But once it reached temp, the sound appears at the indicated revs. Does that indicate maybe something else?