Help with buzzing sound please

T

tomTVR

Active member
My second Z4 and the second time I've suffered this noise!

Symptoms only occur when the engine is under heavy load approx 700-1100rpm, especially noticable at maneuvering speeds. It's like a buzz/rattle from the transmission area which goes away as soon as the revs rise.

My old 3.0i roadster developed this after a while, I sold it before I ever got it diagnosed.

Now my 3.0si coupe was fine until it went in for a new clutch/flywheel and I noticed the familiar noise was back.

The problem isn't really noticable enough to justify having the garage fix (for free) but it annoys me!

Thoughts, maybe exhaust touching the heatshield?
 
tomTVR said:
My second Z4 and the second time I've suffered this noise!

Symptoms only occur when the engine is under heavy load approx 700-1100rpm, especially noticable at maneuvering speeds. It's like a buzz/rattle from the transmission area which goes away as soon as the revs rise.

My old 3.0i roadster developed this after a while, I sold it before I ever got it diagnosed.

Now my 3.0si coupe was fine until it went in for a new clutch/flywheel and I noticed the familiar noise was back.

The problem isn't really noticable enough to justify having the garage fix (for free) but it annoys me!

Thoughts, maybe exhaust touching the heatshield?
Click to expand...


First thing I thought of before I finished reading your post was exhaust heatshield ??.... especially since the mechs had the gear box out and maybe the exhaust for access , maybe they bent the shield a little ! take it back, a quick look while on the lift will find it I'm sure
 
ive got the same problem Tom and it seems to have appeared after I removed my exhaust to do the bypass mod.

Ive checked under mine a few times & it doesnt seem to be any heat shields or anything loose.

If you do manage to figure it out please let me know lol
 
Did you get this diagnosed properly and fixed?

I think I'm having the same buzzing sound just after starting the car when accelerating under load. The noise is like the sound of a wasp trapped underneath the car. It's ever so subtle but I can just about hear it and feel it cut through the normal low smooth rumble of the car.

The buzzing stops (audibly) once the speed picks up and after a few minutes of driving. I assume it stops because the car has warmed up? It only happened recently but happens every time I start driving the Z4 now.
 
Same problem, recently at the garage due to oil leak caused by seized bolts, now there is a rattle at low revs that sounds like it's coming from n/s front.

Additionally the exhaust sounds a fair bit louder too, so I'm worried they didn't properly secure the manifold if removed or dislodged some other part of the exhaust system.
 
I had buzzing and humming sounds with approx 70kmiles. One constant hum when engine warms up and one buzzing sound that sort of raised with the revs and seemed to disappear after 3krevs... Very annoying.

Had a bmw service. Problem solved. Whatever they changed or replaced did the job for me
 
Hi, I have the same sound/noise with my 2005 3.0i Z4 (35.000km). Like loud wasp under or in front of car.

When I drive the ramp of my parking garage up at 1000-1100 RPM I hear the same sound. Also when I drive at this RPM in 3rd gear and accelerate I hear the sound. Just one second then is gone. Engine runs fine. Also no idle problems.
A mechanic had a short look. He thought it’s the idle control valve that makes this sound when it’s pass over from controlled state by the engine control unit to „free hanging around“ (no input signal).
I‘m not sure if it is this. We cleaned the ICV but it doesn’t help.
When the car is warm the noise get quieter or is not to hear.
I think it’s some loose heat shield or bolt from the exhaust. But I can’t found something until now.

Have anyone found out what is the problem?

Thanks and greeting from Germany.
 
I had this after I put my Supersprint catback on.

I don't want to give false hope but for me it was the heat shield - it covers the differential and sits right around the muffler.

Initially, i discovered a screw for the shield was loose and the washer was rattling. Tightened that up and the noise reduced. Baffled, I took the entire metal shield off and realised that the end flap must be vibrating against something - nothing holds it in place.

You can try bending it outward a bit and see if that helps. I personally ended up covering hte entire shield back with noise/heat insulation foam. No more buzz :thumbsup:
 
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