Author Topic: howling noise (Read 4832 times)

strad · « **on:** April 02, 2009, 11:04:15 AM »

Sounds like it's coming from drivers side rear. Noise is apparent from about 60 mph through about 75 mph. Sounds very much like a wheel bearing. However, sound gets louder if I'm on the gas and softer if I let off (driving in a straight line). I have not tried the cornering load test to see if it gets louder or softer when loaded/unloaded. The on/off power bit mentioned above has me a bit mystified because I've not seen a bad wheel bearing behave that way. What else could it be?

JP 91iS · « **Reply #1 on:** April 02, 2009, 11:50:06 AM »

How is the tire on that side? Could be the differential going out?

gearheadE30 · « **Reply #2 on:** April 02, 2009, 12:47:28 PM »

Sounds like diff ring and pinion noise. The mount is offset to the driver's side, so that might cause the sound location. Try the cornering test; it will narrow things down a lot.

strad · « **Reply #3 on:** April 02, 2009, 01:37:33 PM »

Quote from: JP 91iS;69275

How is the tire on that side? Could be the differential going out?

Tire has about 2000 miles on it (all four of them do actually). It's in good shape. I was wondering about the diff myself. I'll try the cornering test next time I get my hands on the car (it's the wife's dd, not mine).

xwill112x · « **Reply #4 on:** April 02, 2009, 01:41:11 PM »

diffrential.

go pick up a used medium cased 4.10LSD out of a autotragic 325i

strad · « **Reply #5 on:** April 02, 2009, 06:41:47 PM »

Is that a direct bolt on? As in no fooling around with the halfshafts or the driveshaft?

xwill112x · « **Reply #6 on:** April 02, 2009, 07:28:49 PM »

yes sir.

just did it to mine last month myself. fairly easy job.

strad · « **Reply #7 on:** April 04, 2009, 04:58:26 PM »

Update: it does not appear to be wheel bearings, after the cornering load/unload test. I drained the diff fluid and noted the presence of some metal, very fine particles (after 18k miles in the diff). Not a terribly large amount, though more than I saw from my 328 after similar mileage. I'm almost wondering if the (worn out) muffler is giving some sort of resonance between 2700-4000 rpms that I'm not able to hear at lower speeds. I guess I just keep monitoring, and maybe replace the catback, which I know needs doing.

Is Ansa terrible? All I'm looking to do is a durable stock replacement.

xwill112x · « **Reply #8 on:** April 05, 2009, 03:44:38 PM »

Quote from: strad;69445

Update: I drained the diff fluid and noted the presence of some metal, very fine particles (after 18k miles in the diff). Not a terribly large amount, though more than I saw from my 328 after similar mileage.

holy shit

it should be obvious it's your diff.

strad · « **Reply #9 on:** April 10, 2009, 09:35:24 AM »

Yeah I'll get one. Gonna take me a few months though -- BMW diffs are not really available at local junkyards. In the meantime that 410 better hold together lol.

xwill112x · « **Reply #10 on:** April 10, 2009, 10:19:33 AM »

don't yank it around and you'll be ok hopfully.

most of the time, 4-5k clutch dumps or snatching 2nd spinning kills them.