MS3 Whining sound

Hi
I tried to search for this but couldn't find anything.

My 2008 speed 3 recently started whining at low revs and up to about 4-5000. At low revs it sounds like a race car transmission and then as the boost kicks in it's a high pitched whistle. It is related directly to the amount of gas pedal depression/fuel going into the engine and is not locked to the revs. I have taken it to both my mechanic and a Mazda dealership and neither know what it could be.

Any ideas?

B

 

Alternator whine? Try to record it.

 

Get a buddy to help you locate where in the engine bay this sound is coming from. That and sound clip as Raider mentioned would greatly help us help you.

 

Does this happen in gear or neutral?

 

In b4 turbo soundz from aftermarket intake.

....Or power steering pump...

 

I had a whine that corresponded with engine speed as well. I used a stethoscope to narrow it down to the passenger side. Alternator bearings were shot. Had my brother rev it up while I stared at the alternator pulley and saw it flex. Got a used one. No more whine. I still changed out the idler and tensioner pulleys with a new belt before I found it. I thought it was the turbOh for a second too.

 

Thanks guys.

@neganox - it happens in gear, neutral and when the clutch is depressed in gear. There is no change in any of these circumstances. Therefore I don't think it's transmission related.
@Mauro_Penguin - It doesn't change when steering left or right so I don't think it's the pump. Regarding the intake, this car is stock, I have not modified it and the friend I bought it from didn't modify it either.

I'll try to record the sound and upload it. My mechanic did say he thought it might be the alternator on it's way out. I'm OK with that because if it fails that won't be catastrophic. My main concern is that it's the turbo bearings or an air intake leak.

 

Ok so I tried to record the sound. Please see the attached files. Be patient, they are not that great and the whine is barely audible but you can hear it.

 

So it's fixed. It was the turbo. It had 50 thou play in the main bearing. My guy managed to find a used one with only 30,000 km on it. Cost me CAD 2,000 all in to have the work done but at least it's fixed.

FYI for a new one the way he put it was "it'll take 10 years and a million bucks" which I took to mean that they have to be imported from Japan and cost a lot. I did get an estimate from Mazda and they said the part is about CAD 3,000.

Cheers

 

You paid $2,000CAD for a used turbo install...? That seems like a lot more money than you should've spent...

 

Shoot... I know where I'm selling these 2 K04s I got sitting around... lmao