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OK next problem, or maybe it isn't a problem at all?  Cruising on the highway I can hear a quiet noise from the rear of the car.  It doesn't change at all when I accelerate or decelerate.  Sort of sounds like the tires.  Or is a little tire like noise normal?  I suppose I should rotate the tires and check the gear lube.  On the front drive, is the gear lube the same with the standard shift transmission or is it separate?  The tranny was rebuilt about 5,000 miles ago (and a new clutch).

 

Is there anything else in the drive train that I need to check gear lube?  I'm a newbie to all wheel drive, is there a front to rear differential in addition to the front and rear differentials.

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You might want to list the year, mileage etc.   Could be tires or wheel bearings.   Search wheel bearings and it will help you isolate if that is the issue etc.

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You might want to list the year, mileage etc.   Could be tires or wheel bearings.   Search wheel bearings and it will help you isolate if that is the issue etc.

Oops.  2004 Forester, 205,000 miles.  I couldn't hear it until I fixed the exhaust leak.

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Growling noise or helicopter (wuuhb wuuhb) = wheel bearing. changes with speed or with load (turn hard left/right)

Whine or whistle type noise that changes slightly with speed but more when accelerating/decelerating is probably rear differential. Rear diffs are tough and don't usually have problems on these. Wheel bearing is far more common and most likely.

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does the sound change at all depending on the road surface? if yes, then probably tire noise - if no, then it is most likely something else.

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The front and center differentials are part of the transmission, they are all lubricated with the same oil.

Besides the engine, transmission, and rear differential, there isn't anything else you need to lubricate or change the oil on.

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Does it get more noticeable above a certain speed?  Usually wheel bearings start making noise about 30-40mph (at least mine did).  Apparently the Right Rear is the worse culprit on that model era.  (I've changed 3 of 4 on my '03 Forester)

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My 2002 Forester has had the Left-rear wheel-bearing changed twice.

Right-rear still has the original wheel-bearing.

 

I found it hard to diagnose a faulty wheel-bearing:

- rear noise gradually gets louder over time;

- jacked-up rear wheels - no apparent looseness;

- jacked-up rear wheels - listened with stethoscope while hand-turning wheels - nothing heard to confirm bearing problem;

- checked hub-temperatures with infra-red gun after long run - nothing obvious noted.

 

The noise was obviously from the rear, but I couldn't tell if it was left or right.

My wife kept saying: 'It's the LEFT', but I couldn't be sure.

She was correct. It eventually got loud enough to pinpoint the noise to the left-rear bearing.

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The front and center differentials are part of the transmission, they are all lubricated with the same oil.

Besides the engine, transmission, and rear differential, there isn't anything else you need to lubricate or change the oil on.

Thanks!  The transmission was rebuilt 10 months ago, I don't know how far into it he got or what was wrong that he had to have it rebuilt, but I know the transmission shop and they are top notch.  I have the bill from it and I believe it was around $1700.  (stick shift)  And he put in a new clutch also.  I pulled the dipstick for that and it's fine.  I checked the rear differential and the lube looks like new so I'm guessing the tranny shop replaced that lube also.  That lube does stay clean a lot longer than the motor oil, but it sure doesn't look like it's been in there for 200,000 miles.

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The sound is not noticeable below ~ 30 - 40mph.  When it does start it's probably faint enough that 95% of people wouldn't even notice or bother with it.  Maybe I'll just turn the radio on. :)

Seriously though, if the radio was on at a medium volume, I believe it would cover up the noise.  I just tend to hear and worry about any little noise I hear.

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If it's that faint, it's probably normal hypoid gear noise. Ignore it until it gets louder. It'll take a while.

 

I had very noticeable rattling noise from the transmission in my old 95 for 45k miles. Knew it would blow up one day... Car got too rusty and needed too much work to pass VA inspection anymore back in October and that trans never did let me down.

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If it's that faint, it's probably normal hypoid gear noise. Ignore it until it gets louder. It'll take a while.

 

I had very noticeable rattling noise from the transmission in my old 95 for 45k miles. Knew it would blow up one day... Car got too rusty and needed too much work to pass VA inspection anymore back in October and that trans never did let me down.

 

Wouldn't gear noise change with changes in the throttle from engine braking to coasting with the clutch disengaged to accelerating?

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have you driven a vehicle with an open cabin like this, maybe it is just more noise than you might get with a sedan or larger vehicle?

 

sit in the back trunk area and put your head to the floor if you have to - try to identify if the sound is: 

1. actually in the rear (under trunk) or more central (center console/rear seat area). 

2. is it left, right, or center? 

 

if this is an issue normally it's a rotor lightly dragging something (bent dust shield) or a wheel bearing, which would both be identified as left/right instead of center. 

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have you driven a vehicle with an open cabin like this, maybe it is just more noise than you might get with a sedan or larger vehicle?

 

sit in the back trunk area and put your head to the floor if you have to - try to identify if the sound is: 

1. actually in the rear (under trunk) or more central (center console/rear seat area). 

2. is it left, right, or center? 

 

if this is an issue normally it's a rotor lightly dragging something (bent dust shield) or a wheel bearing, which would both be identified as left/right instead of center. 

Yes I drive a 1 ton cargo van.  I can hear that rear differential slightly when on the throttle, but it's been doing it since new.  And well it's a truck so it's going to make a little noise.  The sound in the Forester isn't nearly as high pitch.  May have time tomorrow to rotate the tires and see if it moves up front.  If not, I'm guessing 1 or 2 wheel bearings, but it's not bad enough to worry about.  I only asked about it to see if this noise is normal or not, it's not nearly loud enough to really worry about.

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