What is this noise?

[Majikal]

When Im at highway speeds, mostly in late 3rd, all 4th and 5th gear, the engine kind of whines. It's hard to explain the sound, its not like two moving parts rubbing and making noise, it's more like an electrical whine. It only happens when I accelerate, and goes away when I let off the pedal. The faster I go, the louder it gets. Anybody know what this noise is?

[fretburnr]

diff whine? transmission whine?

[Turf1600]

Is it coming through the speakers? If not, check your tranny fluid. It could be interference from the spark plug wires.

[eyagel]

probably tranny whine or just alternator noise through your speakers.

[Majikal]

Its not coming through the speakers... I actually first noticed it when the speakers were disconnected. Maybe tranny whine.

[AndrewBird]

Factory supercharger. ;)

[DarkWing6]

Is it only when the car is under load (you are still accelerating)?

[Shoomakan]

It could be many things, dude. A vacuum leak will do that, as will a worn flywheel to clutch bearing.

I fixed that today, I really DID have a factory supercharger... lol

[Majikal]

Is it only when the car is under load (you are still accelerating)?

Yeah it's only under load at higher speeds. If I stomp on it from a stop, it doesnt do it in the higher RPMs. It only happens above 50 mph or so.

[Majikal]

It could be many things, dude. A vacuum leak will do that, as will a worn flywheel to clutch bearing.

I fixed that today, I really DID have a factory supercharger... lol

wouldnt a vacuum leak throw a CEL though? I left my breather hose disconnected by accident when I changed all my belts (i took the airbox out for more room), and the car threw a CEL and would stall out. I think a vacuum leak would at least throw CEL.

Worn flywheel/clutch bearing is def. a possibility though.

The list of things I should change on this car is amazing. lol

[DCColegrove]

The transmission and differentials are loud in these cars...just the way they are. And if we are talking about an M42 powered IS for one the M42 whines (but only if the timing chain is good) and these particular M30s came with minimal noise suppression material.

Now having said all that...If the noise is erratic or extremely loud some thing could be wrong...I'd have to hear/feel it to tell you.

[Majikal]

I def. wouldnt call it eratic, and it's not REALLY loud, but noticeable. Like, I cracked the sunroof up today and I could barely here it over the wind noise on the highway. Maybe it's just the engine and/or tranny, its an m42 318i. Im just used to my Focus, that was quiet as hell before the exhaust rebuild.

[PiercedE30]

Sounds like diff whine.