loud humming sound

[makken]

Getting a loud 'humming' sound coming from the car. I don't really know how to describe it other than it kind of sounds like a loud exhaust.

Here's what I've observed so far:

1) it begins at around 30mph; by 60 mph its very noticeable, and by 80 mph, its the dominating sound that the car makes, completely drowning out the engine noise, exhaust, road noise, etc.

2) Aside from the sound, I haven't noticed any other effect on the car: there's no vibration, the car doesn't pull one way or another, or feel sluggish.

3) its engine speed and gear independent -- the sound is the same at 60mph @ 2.5k rpm in 5th gear as it is @ 4.5k rpm in 3rd gear.

4) the sound is the same under acceleration and braking.

5) the sound is lessened when I make a right turn -- completely goes away when I make sharp right turns. Left turns have no effect on it.

Based on that, my best guess is that its coming from the differential. I had the oil flushed and replaced on it; there didn't seem to be anything out of the ordinary on the oil coming out, and the new fluid had no effect on the sound.

Any ideas on what else it could be, or what would be causing the diff to make such a sound?

Oh, car is a 97 BMW 328is with 194k miles

Thanks

 

[Sluggo]

Wheel bearings, could be any or all four corners.

 

[halik]

Getting a loud 'humming' sound coming from the car. I don't really know how to describe it other than it kind of sounds like a loud exhaust.

Here's what I've observed so far:

1) it begins at around 30mph; by 60 mph its very noticeable, and by 80 mph, its the dominating sound that the car makes, completely drowning out the engine noise, exhaust, road noise, etc.

2) Aside from the sound, I haven't noticed any other effect on the car: there's no vibration, the car doesn't pull one way or another, or feel sluggish.

3) its engine speed and gear independent -- the sound is the same at 60mph @ 2.5k rpm in 5th gear as it is @ 4.5k rpm in 3rd gear.

4) the sound is the same under acceleration and braking.

5) the sound is lessened when I make a right turn -- completely goes away when I make sharp right turns. Left turns have no effect on it.

Based on that, my best guess is that its coming from the differential. I had the oil flushed and replaced on it; there didn't seem to be anything out of the ordinary on the oil coming out, and the new fluid had no effect on the sound.

Any ideas on what else it could be, or what would be causing the diff to make such a sound?

Oh, car is a 97 BMW 328is with 194k miles

Thanks

You need right front wheel bearing.

Sukhoi caught it, head's not working today.

 

[punjabiplaya]

You need left front wheel bearing.

+1

 

[Sukhoi]

You need left front wheel bearing.

I'm not saying you're wrong, but why does adding load make the noise go away?

 

[halik]

I'm not saying you're wrong, but why does adding load make the noise go away?

Durrr RIGHT front bearing, have my head stuck in CFA

 

[Bartman39]

I'm not saying you're wrong, but why does adding load make the noise go away?

If he is making hard right hand turns it unloads the right side bearings... Normaly on cars and trucks that have reg spindle type bearings this applies... But on newer sealed bearing trucks and some cars it works just the opposite as I have found...

 

[halik]

If he is making hard right hand turns it unloads the right side bearings... Normaly on cars and trucks that have reg spindle type bearings this applies... But on newer sealed bearing trucks and some cars it works just the opposite as I have found...

You could have the damage on the upper side of the outside and turning really hard to the right would unload the car weight off the side and have the wheel be supported by the upper race of the bearing... but the odds of that are minimal.