Help with Whine

[TheBobmanNH]

Hi, I have a new to me E85 Z4 convertible (89k miles), and it has a bit of a whine from the engine under acceleration / load. Brought it to a well-reviewed local shop and they "couldn't hear it," which seems crazy -- it's not loud but it's definitely noticeable, even to my damaged 40-something ears.

While I know a general "there's a whine on acceleration" is way too vague to diagnose on the Internet, are there any common things I can look at? It's tough because it won't do it at idle or revving in neutral so I can't just stick my head under the hood.

It's a 5-speed, does it in any gear. Increases in pitch a bit with engine RPMs but not much.

The noise doesn't "bother" me per se, I just don't want to find out it's something serious after it's too late.

Thanks!

[Steeler]

Originally Posted by TheBobmanNH

Hi, I have a new to me E85 Z4 convertible (89k miles), and it has a bit of a whine from the engine under acceleration / load. Brought it to a well-reviewed local shop and they "couldn't hear it," which seems crazy -- it's not loud but it's definitely noticeable, even to my damaged 40-something ears.

While I know a general "there's a whine on acceleration" is way too vague to diagnose on the Internet, are there any common things I can look at? It's tough because it won't do it at idle or revving in neutral so I can't just stick my head under the hood.

It's a 5-speed, does it in any gear. Increases in pitch a bit with engine RPMs but not much.

The noise doesn't "bother" me per se, I just don't want to find out it's something serious after it's too late.

Thanks!

Could be a number of things.
Obviously rotating when car is moving.
Wheel bearings, rear diff, transmission gears etc are all potentials.
Try and narrow down to a particular area.

I have my engine and trans on solid mounts, so I get feedback through those that is a whine. Possibly your engine or trans mounts are going away.

[racerbruce]

Help with w(h)ine....I suggest a good Cabernet Sauvignon or perhaps a dry Merlot

No vibration(s)?
Have all fluid levels (engine/transmission/differential) been checked?

Suggest using a stethoscope to listen for this noise by touching all surfaces under the hood:
https://www.amazon.com/Powerbuilt-64...dDbGljaz10cnVl

[TheBobmanNH]

Originally Posted by racerbruce

Help with w(h)ine....I suggest a good Cabernet Sauvignon or perhaps a dry Merlot

No vibration(s)?
Have all fluid levels (engine/transmission/differential) been checked?

Suggest using a stethoscope to listen for this noise by touching all surfaces under the hood:
https://www.amazon.com/Powerbuilt-64...dDbGljaz10cnVl

I have that very same cheapo stethescope, the issue is that it only happens when driving so it's a little tougher to probe

Thanks though

[racerbruce]

Originally Posted by TheBobmanNH

I have that very same cheapo stethescope, the issue is that it only happens when driving so it's a little tougher to probe

Thanks though

Got it.
A thought - although you hear the noise when driving, have you listened via stethoscope to the alternator, water pump, power steering pump, etc, etc.

Fluid levels? Last time fluids were changed?

Is it pronounced enough that you could drive by and someone could listen from the sidewalk?

[Adam_F30]

If the whine is on acceleration, it may be to a tear in the intake boot or vacuum lines. You didn't mention any codes popping - have you scanned the car yet? I just changed my intake boot after getting some codes showing the engine was running lean. Good luck!

[tomjonesBT33]

I recently replaced the idler pulley, a/c pulley and tensioner in mine. It would whine at a cold start and then go away after a few minutes. Turned out to be the bearings in the idler pulley.

Not exactly the same symptoms as you describe but more food for thought