[SVO1]

Taking the kiddos to school today in my wife's 97 LOB, and I noticed that when coasting it has a rotation banging that sounds like it is coming from the rear end.
As soon as you give it a little gas to be under load it goes away, and also when you hit the brakes, but them it comes back when you let off.

With it in the air the u-joints/cv's feel tight, rear diff fluid was full and a little dirty (draining it right now, no real signs of metal or anything in the fluid)
The center support bearing I can push up and down a bit, I don't know if that is acceptable?
Anyone had a problem like this? I searched and found a few threads but nothing that was seemingly resolved. Also my Buddy at the Local Suby Dealer said it does nto sound like anything they have really seen.

 

[ETC]

There shouldn't be any play in the carrier bearing. Is it the carrier mount or the bearing itself that has play ? If it's the mount, tighten it up and your probably done. If it's the bearing, talk to your buddy about a replacement or have it rebuilt. Some say the shaft isn't rebuildable, it is. You just have to compare the cost of a new shaft vs the rebuild job.

Check the u-joints for slop as well.

A few on here have had their shafts wear out at either the carrier or the u-joints, one actually dropped a shaft on the ground.

 

[upjeeper]

ever find out what happened??
this sounds like what i'm experiencing

 

[Nico777]

And for me, 9 years later. '06 2.5 EJ25 auto RHD. BIG clunk when changing reverse to drive not in selector but when power is applied.

Drives beautifully, but with a rhythmic donk sound, speed (not gear or revs) related. Also does it cruising in neutral but not when turning left. Not super loud just annoying. Getting slightly worse over time.

My guy says it is auto trans, changed oil out, no change. Needs an inner tie rod replacing drivers side in RHD. Front wheel bearings, ball joints, and axles were all replaced. This car has done a LOT of hard country miles and is approaching 200,000 miles.

Anyone?

 

[seagrass]

And for me, 9 years later. '06 2.5 EJ25 auto RHD. BIG clunk when changing reverse to drive not in selector but when power is applied.

Drives beautifully, but with a rhythmic donk sound, speed (not gear or revs) related. Also does it cruising in neutral but not when turning left. Not super loud just annoying. Getting slightly worse over time.

My guy says it is auto trans, changed oil out, no change. Needs an inner tie rod replacing drivers side in RHD. Front wheel bearings, ball joints, and axles were all replaced. This car has done a LOT of hard country miles and is approaching 200,000 miles.

Anyone?

Check the transmission mounts as they can cause this sort of noise when worn or broken.

Seagrass

 

[Nico777]

Thanks for that. Another option. Are you referring to the clunk noise (not annoying but concerning) or the rhythmic donk noise from centre of vehicle (really concerning)

 

[yarrgh]

Also take a look at the rear diff bushings.

 

[Nico777]

Check the transmission mounts as they can cause this sort of noise when worn or broken.

Seagrass

High are you referring to the shift thwack/clunk noise when engaging, or the rhythmic donk noise when cruising?

 

[Nico777]

Also take a look at the rear diff bushings.

Thanks but I disengaged AWD by connecting that fuse and we still have both noises so it ain't that!

 

[seagrass]

High are you referring to the shift thwack/clunk noise when engaging, or the rhythmic donk noise when cruising?

The clunk noise when engaging

Seagrass

 

[Nico777]

The clunk noise when engaging

Seagrass

Thanks Seagrass the driving noise is much more concerning. I had a similar mystery noise last yr and mechanic who did wheel bearing hadn't locked off the wheel. Talk about dangerous could have killed us. He moved away unfortunately (or fortunately). Sounds like carrier bearing or more likely bushing or some kind of cv, as donk noise goes away when turning.

 

[Nico777]

Ok so I've disengaged AWD and tried it out in neutral. Still makes rhythmic donk based on speed not gears. Also doesnt do it turning left but does driving straight or going to right in a RightHandDrive vehicle. Wheel bearings ball joints and front axles all have been replaced. Right hand inner tie rod to be done soon.
Can the auto trans still make noise coasting in neutral? Anybody?

 

[Nico777]

It was the inner tie rod, and the boot was rock hard and was making the racket. And to think I nearly replaced the transmission! Mechanic was wrong I was correct. The turning issue convinced me it was steering not drivetrain. $150 fixed plus wheel alignment. Happy camper!

 

[Nico777]

Ok correction time. Not tie rod, once alignment was done thwacking noise is back! Has to be wheel bearing, but they are quiet, tight and spin ok when checked manually. And replaced only 3 yrs ago. Weird.

 

[cardoc]

Is it loud enough to record it? Post it somewhere and link it here.

I can think of a few things
Wheel bearing, one hand on the spring while the other spins the wheel, you'll feel it

U joint in the driveshaft; usually accompanied with vibration

Sway bar links, allow the suspension the
rattle

Lower control arm bushings

Front diff carrier bearings

Something else you can do is jack it up and hang it on jack stands high enough that you can get under it. Run the car in gear with someone inside and see if it makes the noise with the wheels off the ground. Getting under the car will allow you to pinpoint a location if it does. You also may be able to hear it if it's a wheel bearing.

 

[Nico777]

Thanks for your input, really appreciated. I have a spare wheel bearing around so I'll try that first. (The wheel alignment guys test drove it twice and swore blind it's the bearing. It doesnt make the noise when turning left)Then we'll try that other stuff. That clunk when putting on power (rather just into gear is still there, maybe related, maybe coincidence). Driving me kerrrazzy!

 

[plain OM]

Just to add to @cardoc 's suggestion, if when the car is raised the AWD fuse is installed, the fronts will turn, but the rears shouldn't to any degree. If the repetitive sound is still there, it's in the front drive train. If it's not, and returns when the fuse is installed and the rear drive train is working, that points to the rear system. Sounds and vibrations can be deceiving; this might help narrow down the area of the source.

 

[Nico777]

Thanks, yes I've disengaged the AWD btw so it definitely is from the front. Just can't see how it's front diff (my mechanic's opinion) as it's reliant on driving direction, not load. Does it at any speed over 10mph, including rolling in neutral, braking and accelerating. So it's def not CVs. My suspicion is a faulty/dry wheel bearing. Update in a couple of weeks

 

[Nico777]

Well here we are months down the track, and it is, definitively, the front diff. Well I never. Probably caused by a neglected front end/odd tyres by a previous owner. Big bucks coming up, still drives fine, just with ever-noisier accompaniment. Murphy's Law wins again.