I spoke to the workshop manager and he chose his words carefully.

Essentially, he said that it is normal for a 5 series. I said a 525d, he said yes. I said what about 530d, he said he would have to drive one to be sure. You get the idea.

He did say that at these sorts of revs, it is where the turbo starts to work etc.

He suggested I drove a 530d to see if that does it.

As I said, he chose his words very carefully but I concluded from what was said, is that 525ds do resonate at 1700rpm.

The guy who took my car in yesterday for me, agrees that there is a resonance - he thinks from the exhaust system.

Seems like a design flaw to me.

Have already sent another email to BMW UK.

The saga continues...

 

Thanks for the update.

Does this only happen to Auto models? I have tried to see it the noise occurs on my car but I cannot hear any change around those revs. Perhaps it might be from the Auto Box? Is that possible?

 

I don't honestly know. I wouldn't have thought so as it will do it at standstill in N.

Glad you are not affected though.

Parhaps I should just turn the stereo up!

Regards,

 

I have the same problem although I doesn't have this sound always. However it doesn't matter if the car is cold or warm, drive slow or fast, ... when it starts it stays. I tried to find how I can reproduce it on command but haven't found the trick yet. When my car doesn't make that noise it is the car I intended to buy, a dream, silent, no motor noise, ... It's really annoying when it's there.

As read above one of my thoughts about the noise went in the direction of the exhaust pipe too. Imagine you have a hole in your exhaust pipe with a shutter that slowly starts to open at about 1500 rpm, fully opens at 1700 and slowly close again till 1900 rpm.

I had another 525d 2008 LCI for one day to test and this car didn't have that noise so in my opinion not all cars have it or maybe it's there too but not so prominent.

My next idea is to record the noise with a HQ digital recorder with two microphones, 1 in the inside and 1 in the engine compartment (both on one stereo track - left/right). Then make a recording with and without the noise. This way maybe I can figure out something and have some evidence of the difference. When I have them I'll post them here so other users can identify the sound too. This can take a while because I have to find the correct microphones to do this.

 

And another update. A busy day on the resonance front.

Went and spoke to my dealer and got him to sit in the car.

Brought it from 1500 through to 2000rpm at standstill. He agreed it was there at 1700rpm and some sort of resonance.

Again he said all 525d are like this. Someone was looking at one in the showroom and I tasted blood not saying anything.

We then tried the same in a 530d LCI. There was a tiny bit of noise at 1700rpm but only just noticable if you really listen for it. If this was the level of mine I wouldn't be worrying about it.

This does lend weight to your theory that something is happening at this rev range in the 2993cc diesels (single turbo) - something to do with variable vane turbo maybe?

He said he would look at PUMA, some sort of international BMW problem logging database and call me tomorrow.

I then went to another dealer 30 miles away for a second opinion .

This time the manager said that yes it was resonance but no it shouldn't be like that and lets book the car in to see if they can do something.

He tried opening and closing the vents - no difference; thinks the exhaust might be to blame.

Remember how Alfasuds used to rasp (before they rusted away)?

So we we have confirmation that it isn't just me being over fussy, and I have dealer who wants to fix it under warranty.

It goes in next Tuesday so fingers crossed!

Regards,

 

Hang on, is there a common thread here?

Three people suffer the problem, all on cars built in June or July.

Is there anyone else who suffers the resonance who's car was built outside of these dates?

Could be a duff batch of exhausts perhaps hence why some earlier or later cars are not affected??

 

Good luck and of course ... keep us posted and if your new dealer has found some reference in the Puma database please ask the number so others can use it to state their complaints. Can hardly wait for the result.

 

I took delivery 1st of June so I guess that it was built in early May.

 

Hello !

very interesting this topic...

What about the 325d 3.0d, do they have the same resonnance problem ?
I'll try to ask on other forums, I'll let you know.

 

Welcome.

I haven't been able to find any reports on 325d 2993cc, but yes please let us know.

Regards,