Rear Differential Noise

Amadore

New member
Hey everyone,

I have a 2000 Impreza OBS, 2.2l manual and since a few months after I bought it, you can hear a sort of grinding noise coming from the rear, from where I assume is the differential.

The noise started off very quiet, and at first my brother thought it was a bad wheel bearing, but it's gotten a lot worse to the point where it's not only bugging the hell out of me but causing a lot of concern. The grinding noise is consistent and doesn't lessen or worsen with speed.

First of all, any thoughts that it is in fact the rear dif? If so, any suggestions on an affordable replacement or a dif rebuild?

Any help at all would be appreciated. Thanks


 

Matt

New member
Prob should drain the fluid and check for metal first. It's either rear diff or bad wheel bearings.

 

Amadore

New member
Yeah, I'm going to drain the fluid soon, once I have some time. As for the wheel bearing, it's definitely not that because I've checked each wheel for the telltale movement when you have a bad bearing. All of them were snug.

 

IBratmanI

Subaru Ambassador- AdidaSubarus
Yeah, I'm going to drain the fluid soon, once I have some time. As for the wheel bearing, it's definitely not that because I've checked each wheel for the telltale movement when you have a bad bearing. All of them were snug.
That's not always true with these cars. I have had, and seen many bad bearings on these cars that have NO movement at all. And others that do.

 

Amadore

New member
I'd rather have a wheel bearing problem than a dif problem. With that said, does anyone know of someone who rebuilds/repairs suby difs? If it turns out to be the dif, I'd like to either get a replacement or have it repaired.

 

IBratmanI

Subaru Ambassador- AdidaSubarus
You can pretty easily find a good used replacement. They rarely fail, so there are plenty of them out there in junk yards pr cars that are being parted. It's actually probably cheaper to replace the rear diff, than it is to replace the bearings. The rear bearing s are a pain to do in these cars.A lot of that has to do with the long bolt that holds the lateral links to the knuckle.

 

Chris

YARRR SUBY MONSTER!!
I'd rather replace the diff than a wheel bearing on one of those. Diff is a 30 minute job. I have a 4.11 diff, but I'm fairly certain yours is a 3.90.

When the diff fails it's usually a nasty whine that starts off only happening on accel or decel. Jack it up and spin the back wheels slowly by hand, if they don't rotate smoothly, and sorta feel gritty, it's bearings.

 

Amadore

New member
Well, I found a car maint. log that I had lost, and it says the previous owner had the rear dif rebuilt at 105k as well as BOTH rear wheel bearings replaced then as well. Currently I'm at 122k. So NOW my question is, would bearings and/or a rebuilt rear dif really go bad so quickly?

 

Chris

YARRR SUBY MONSTER!!
Rebuilt diff? I see no reason why anyone would rebuild one when they cost $50 at the junkyard and don't fail very often. Perhaps it wasn't rebuilt very well.

 

Chris

YARRR SUBY MONSTER!!
The only diff that may be worth rebuilding is, say, if you had a 4.44 forester XT diff that made a bad noise.....

 

inski

New member
Jack it up so all 4 wheels aren't touching anything and rest the whole car on jack stands.  Have helper drive to 40mph and hold it steady at 40mph in 3rd gear.  Listen to where noise is coming from.  Use a stethoscope or a long screw driver as a stethoscope to pin point noise.

Or, take it to Evergreen and pay them $25 to tell you where the noise is coming from.  Probably a lot safer that way.

You'll need to shell out some money to go any further in life.

 

2point5RS_Dan

HATER DAN
Jack it up so all 4 wheels aren't touching anything and rest the whole car on jack stands.  Have helper drive to 40mph and hold it steady at 40mph in 3rd gear.  Listen to where noise is coming from.  Use a stethoscope or a long screw driver as a stethoscope to pin point noise.

Or, take it to Evergreen and pay them $25 to tell you where the noise is coming from.  Probably a lot safer that way.

You'll need to shell out some money to go any further in life.
Evergreen charged me 50 to confirm that the diff gabe sold me was bad.

 

Amadore

New member
Thanks for your suggestions guys, and beats me why he had it rebuilt instead. Maybe he didn't want to hassle with finding a replacement and replacing it? Who knows. From what he says (I messaged him on FB) the guy who rebuilt was a reputable mechanic in NH. And Nigel, once I pinpoint it's the diff, I'll take you up on that offer. My sube would take a 3.90, right?

Again, thanks guys.

 

messerschmitt

New member
Hi Amadore, I know this is an older post but I was wondering if you confirmed your issue to be related to the rear differential.  I seem to have a similar problem that just occurred few days ago and I am trying to find some clues.  I also have a 2000 Impreza Outback Sport with manual transmission and as I said few days ago I was driving on the highway and when I let go of the gas pedal i heard this heavy girding noise somewhere in the back.  At first I thought maybe it is the wheel bearing or the rear drums since it sounds like a metal on metal grinding; however, the noise goes away when i press the bass pedal or when I throw the gear into neutral.  I bought this car new and it only has 128,000 mile on it with the original clutch, which by the way is near its life but at the moment the gears shift perfectly.  So I guess I want to see if your issue was similar and if you did find out what it was.  Thanks in advance for your help. Dan

 

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