Center Support, Output Shaft Bearings or Differential?

[phredphish]

I have a noise under load, at speed.
I have a noise with no load, low speed (and presumably high speed)

First:
I first noticed the under load, at speed sound driving ~40-50 in 3rd and 4th gears. I would press the accelerator and it would make a humming sound. It got progressively worse and felt almost as if there was power loss when it was happenning.

THEN:
I went shopping yesterday. When leaving, I was going to backup out of a parking space. As I was releasing the clutch, it felt as if I had left the parking brake on (but I didn't). Then, it made a 'clunk' sound and started moving. I shifted into 1st and it did a similar thing (with another 'clunk'). As I started driving, I could hear a regular, softer 'clunk' sound at low speed driving out of the parking lot.

Now: I have the rear end in the air, it in neutral and I spin the driveshaft manually. It sounds like there is a bit of a 'clank' where I believe the center support bearing is. Occasionally the driveshaft seems to lock-up and requires more force than usual to restart the rotation.

Which is it? What's wrong? I checked my guibo and that seems fine (and wouldn't explain many of problems).

Thanks,
Andrew

[EN318isPDX]

I have a noise under load, at speed.
I have a noise with no load, low speed (and presumably high speed)

First:
I first noticed the under load, at speed sound driving ~40-50 in 3rd and 4th gears. I would press the accelerator and it would make a humming sound. It got progressively worse and felt almost as if there was power loss when it was happenning.

THEN:
I went shopping yesterday. When leaving, I was going to backup out of a parking space. As I was releasing the clutch, it felt as if I had left the parking brake on (but I didn't). Then, it made a 'clunk' sound and started moving. I shifted into 1st and it did a similar thing (with another 'clunk'). As I started driving, I could hear a regular, softer 'clunk' sound at low speed driving out of the parking lot.

Now: I have the rear end in the air, it in neutral and I spin the driveshaft manually. It sounds like there is a bit of a 'clank' where I believe the center support bearing is. Occasionally the driveshaft seems to lock-up and requires more force than usual to restart the rotation.

Which is it? What's wrong? I checked my guibo and that seems fine (and wouldn't explain many of problems).

Thanks,
Andrew

I've had 3 Center bearings fail on me (2 different e30's).. it drop the exhaust shield out and inspec the rubber around it.. most likely its busted

[phredphish]

Is this type of thing indicative of a center support bearing failing?

[individualist]

Many times the clunking sound can be traced to the CV joints. Might want to check the support bushing on the differential as well as a loose or broken brake caliper. All of these can produce a "clunk". On the CSB, grab the driveshaft and start pushing/pulling on both sides of the bearing, looking for excessive movement.

[phredphish]

Well, I've finally gotten around to getting under the car and looking at the problem.

The CSB seems to be completely intact (no torn rubber). What is "excessive" movement with regards to the driveshaft and the CSB?

On another note, it looks like there is a slight leak of differential fluid where the input shaft goes into the diff. It hasn't leaked enough to hit the floor, but it is wet and has a single drop.

Any ideas?