Z4 3.0si engine hissing noise

Hi,

Having lurked on here for a while, I've decided to join up... be gentle..!

I've had a search through previous posts to see if anyone else has previously had the problem I am currently experiencing, though couldn't find my exact issue.

After the engine has warmed up, there is a very noticable hissing or high-pitched buzzing noise coming from the drivers side (RHD) of the engine, from around the exhaust manifold.

Took it to BMW but was told that it was normal after the "technician" reeled off a load of spiel which even I could tell he made up on the spot... :headbang:

I can't pinpoint the noise (even after using an offcut of hosepipe as a stethoscope), and obviously its pretty hot down there so I'm hesitant to stick my hand down there to feel for a air leak or anything..!

I've put a vid on youtube in which you can hear the noise (you can hear it better with headphones):
http://www.youtube.com/watch?v=7Si235sVZS4

Comparing it to another vid on youtube of the same engine (though this one has the tappety knocking noise), you can't hear it in there...
http://www.youtube.com/watch?v=Ykc_f-xmSo8

Does any one else's car make the noise that mine does? I'm convinced its not normal - sounds crap when driving with the roof down in enclosed spaces where you'd normally bask in the exhaust note..!

Would appreciate any help.... thanks!
Calum.

Crack in the manifold maybe :idunno:

It is still in warranty? I'd try another dealer to see what they say.

If there is a exhaust leak of any kind, they should be able to find it with the hydrocarbon sensor that they use for emission control testing. The tip of the probe can moved around the exhaust area and should easily show any leaks.

thanks for the replies. I'll have a ring round of other dealers in the vicinity tonight/tomorrow to see if they can take a look.

I agree that it could be a manifold leak - the fact that it only does it once everything gets hot and expands seems to suggest this anyway.

Will keep you posted on the problem. Cheers.

Have just had the exhaust manifold replaced under warranty on my 2006 2.0 just a few days before the warranty expired. It had a hairline fracture and from what I understand (although the technician didn't put it quite so bluntly) it's a recognised weakness on the Z4... :roll:

If it's under warranty I'd get it straight back to BMW and get it looked at. Whereabouts are you? Mine went into Cooper in Cobham, Surrey & they've always been pretty good for me...

thanks!

I'm in Bournemouth, though am willing to travel to get it sorted... issue is getting it somewhere for them to look at when I'm not at work!

Will bear Cooper's in mind though Owen - cheers.

so you first took it to woods i suppose! i've not heard good things about them! :thumbsdown:

http://www.z4-forum.com/forum/viewtopic.php?f=4&t=12686

ccr32....did you find out what was causing the sound?

My z4 is producing a VERY similar noise but only from 1000 to 1100 RPM in drive...never when idle.

Hi,

Bit of a slow reply – I apologise! But no, I never did get to the bottom of the issue. I took the car to an indy who had a listen and confirmed that it was not normal, however as whatever would be required to investigate/fix it would be under warranty, they were obliged to contact the nearest BMW main dealer (Wood’s!) and get it carried out through them. Unsurprisingly, after a couple of weeks, the trail went cold and I have heard nothing since (except the hiss, obviously!).

I now have to take the car into Wood’s again for another issue (see here – http://www.z4-forum.com/forum/viewtopic.php?f=3&t=17984) and might ask them again about the hiss. Potentially the two are related, though I guess I will have to wait and see.

Calum.