howling noise 1999 OBW auto trans

[olivia123]

This is an update to a post from the spring about my 1999 OBW auto trans link below

 

http://ultimatesubaru.org/forum/showthread.php?t=121821

 

The car still makes a howling noise from the passenger side rear when going up hill and stops when you lift the gas pedal. It also makes a kind of rattling sound from the same area right before the howling starts. It does not do this all the time and when the FWD fuse is in it doesn’t do it at all.

 

After having a sub tech and an independent guy look at the car the both suggested replacing the rear diff. The u joints and mid bearing were checked at this time as well. So I had a used read diff installed, had only 46,000 miles on it, and no change in outcome. Still makes the same noises under the same driving conditions and is still quiet with the fuse in.

 

With the rear diff out of the equation what else might be causing this? I have never had a rear cv joint go bad on any of my previous 5 subs so I don’t know what the sounds/symptoms are. Any chance it could be a cv joint?

 

I have read a lot about driving the car with the fuse in and or dropping the read section of the drive shaft. There doesn’t seem to be a consensus on if this is a good or bad idea.

 

As I said in the original post I’m hoping to get another year out of the car and other than this it runs and rides great.

 

Thanks for any help

[johnceggleston]

probably the drive shaft, what else could it be? maybe a wheel bearing but that should make noise all the time. and a really long shot, that i have never heard of going bad, would be the bearing on the trans output shaft to the rear wheels. but again, i have never heard of one going bad.

 

it has to be the drive shaft.

 

how was it ''checked out''? who did it?

[olivia123]

The dealer tech heard the noise with me driving and said replace the rear diff. Didn’t put it on a lift. The independent guy also heard the noise with me driving and we put it on a lift and checked the u joints and center bearing for play. He also said replace the rear diff and he is the guy who put it in.

[johnceggleston]

The dealer tech heard the noise with me driving and said replace the rear diff. Didn’t put it on a lift. The independent guy also heard the noise with me driving and we put it on a lift and checked the u joints and center bearing for play. He also said replace the rear diff and he is the guy who put it in.

 

and both were wrong about the rear diff.

 

what is the chance that they were also wrong about the drive shaft?

 

on a side note,

i just bought a '00 lego wagon w/ 80k miles. it had loud road noise which i figured was due to cheap tires. so i swapped in some other wheels and tires i had in the shed. now the noise is less but not gone. i now think it is a wheel bearing. it sounds slightly different when swerving to the right than when swerving to the left. i think the left rear wheel bearing is making noise.

 

i guess the point is , i'm not perfect in diagnosing noise when they it's in my car much less over the internet. but it certainly wasn't the rear diff. if you had taken a poll here before replacing it i doubt very many, if any, would have suggested replacing the rear diff. they just don't fail very often.

 

if it is not a wheel bearing, it has to be the drive shaft.

 

i would jack up each wheel and rotate it by hand while holding a finger on the strut spring. or better yet, buy a mechanic's ''stethoscope'' (harbor freight <$5.), and rotate the wheel by hand with the probe on the knuckle housing. if all four sound / feel the same, it has to be the drive shaft.

Edited August 11, 2011 by johnceggleston

[olivia123]

Well I certainly agree it isn’t/wasn’t the rear diff and you’re right a few folks on the forum said they rarely fail. So what could be wrong with the drive shaft? I assume it would be in the rear portion of it. I will try the individual wheel diagnoses but we sort of did that with the rear wheels when the car was on the lift. We had them spinning with the engine running at idle in gear.

 

Thanks for you input

[nipper]

The driveshaft needs to be ubolted and inspected. If it is a bad universal joint there is super scary impending doom coming... seriously.

[olivia123]

I think what I will do is take off the rear section of the drive shaft and inspect the u joints and drive the car that way for while. I don’t really need four wheel drive that often and I guess this is better than driving with the 2wd fuse in. I have read some differing views about driving the car with the rear part of the drive shaft removed is it OK to do this?

[johnceggleston]

I have read some differing views about driving the car with the rear part of the drive shaft removed is it OK to do this?

 

 

my 95 has been this way for 40k miles.

 

no worries.

[nipper]

I think what I will do is take off the rear section of the drive shaft and inspect the u joints and drive the car that way for while. I don’t really need four wheel drive that often and I guess this is better than driving with the 2wd fuse in. I have read some differing views about driving the car with the rear part of the drive shaft removed is it OK to do this?

 

 

Inspect all the u joints, not just the rear. If anyone needs a DS there is a rebuilder i like.

[the3rsss]

Easy way to see if the noise is your wheel bearings.....lightly brake while its making the noise. If its a bad bearing, the brakes will take the load off of it and the noise will vanish.