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DISCUSSION => Engine + Driveline => Topic started by: sepehr on January 08, 2007, 09:19:26 PM

Title: Rear end noise
Post by: sepehr on January 08, 2007, 09:19:26 PM

There is a hissing noise coming from the rear of my car. At low speeds, around 30-50 km/h, its an intermittent noise, a regular "ssss....ssss....ssss...".

At highway speeds it a constant hiss from the rear. Changes pitch with speed. Hardly audible with car coasting in neutral, easily audible when in gear and under load.

What can this be? wheel bearings? csb? diff?

thanks

Title: Rear end noise
Post by: kowalski on January 09, 2007, 04:21:46 AM

first check is something is stuck back there... sounds like an odd symptom due to the occurances... because bearings would do it coasting or under load, same with CV's. gears grind so it wont be those, only other things i could think of that would make it get louder as you apply load are the CSB or guibo (both located on driveshaft, if your going to do one do both. can you tell how far behind you it is?

Title: Rear end noise
Post by: sepehr on January 09, 2007, 03:46:03 PM

Ok let me correct myself its audible at highway speeds under any load, it just blends in more with the rest of the racket when the car is put into neutral.

At speed, it sorta makes the same metal/sandpaper like dragging sound a you hear from a dying throw-out bearing.

Sounds like its coming from beneath the rear seat, or the tranny tunnel right in front of the rear seat. I've heard this on other e30's too, it seems to be a common problem.

One of the diff bearings maybe?

I read the fuel pump could make this noise, but I'm sure thats not it, since I don't hear it when the car is not moving.

Title: Rear end noise
Post by: kowalski on January 09, 2007, 04:26:51 PM

the fuel pump will make a whining noise yes. If its in the tunnel thats where the CSB and guibo is. the center support bearing will make a howling noise when its going, and is likely your problem. it would make more noise under load because there is more strain on the drive shaft when under load, but it still spins when your coasting so it will still whine when coasting.

Title: Rear end noise
Post by: sepehr on January 09, 2007, 05:10:20 PM

Thats the thing though there is no howl. Its more like sandpaper on metal

Title: Rear end noise
Post by: kowalski on January 09, 2007, 05:37:10 PM

and you checked that nothing is rubbing the axles, tires/wheels, drive shaft?

Title: Rear end noise
Post by: sepehr on January 09, 2007, 05:43:32 PM

I couldn't see anything.

I think I'll take to Nixon Automotive tomorrow and see if they can diagnose it for me. Too bad I can't afford to let them fix it too. :(

Title: Rear end noise
Post by: kowalski on January 10, 2007, 04:34:23 AM

try classic image, they're a little easier on the wallet and good guys.

Title: Rear end noise
Post by: sepehr on January 10, 2007, 05:54:37 PM

I will thanks. They are on 76th St. in Surrey right?

Title: Rear end noise
Post by: kowalski on January 11, 2007, 01:10:43 AM

yessir

Title: Rear end noise
Post by: tophertii on January 31, 2007, 10:34:15 PM

Any resolution to the problem? I have something similar going on. Curious of the out come.