Subaru Impreza 2.0 GX 2002, strange whirring noise

[mikejbry]

Hi, I could really do with some fellow subaru owners help, so a little about the car first of all.

I bought it yesterday as a reliable (hopefully...) cheap run around for my brother. Its a 2003 Subaru Impreza 2.0 GX Sport wagon, lowish mileage of 85k miles, recent cambelt, plenty of services etc. Overall it seemed like a good buy.

I noticed on the rear differential at the time there were signs of what looked like an old oil leak, coming from above it, so I assumed after a little research its likely to be the breather pipe that can sometimes split.

Anyway, it was bought in a city centre so I couldn't really get it up to much speed on the test drive but all the gears felt fine on the test drive I did manage to do, hence missing the next issue, when the car gets up to 40mph, the slightest amount of throttle will initiate a audible whirring noise, almost like a whine, it continues to happen until 50mph where it stops. Without any throttle it is inaudible, the tiniest dab of throttle and it reappears. It happens irregardless of which gear it is in, it's the speed that brings this noise out.

Some googling suggests the central diff bearings could be at fault? How likely does this sound? Is it possible it's the rear diff but the sound is presenting itself upfront? I might change the rear diff oil, as it looks a very easy job to do on the driveway at the weekend. But if it's the front or central diff, they share fluid with the transmission correct?

Are there any other suggestions on what could be causing this noise?

Any help would be greatly appreciated.

Thanks

Mike

[TEKNOPUG]

mikejbry said:

Hi, I could really do with some fellow subaru owners help, so a little about the car first of all.

I bought it yesterday as a reliable (hopefully...) cheap run around for my brother. Its a 2003 Subaru Impreza 2.0 GX Sport wagon, lowish mileage of 85k miles, recent cambelt, plenty of services etc. Overall it seemed like a good buy.

I noticed on the rear differential at the time there were signs of what looked like an old oil leak, coming from above it, so I assumed after a little research its likely to be the breather pipe that can sometimes split.

Anyway, it was bought in a city centre so I couldn't really get it up to much speed on the test drive but all the gears felt fine on the test drive I did manage to do, hence missing the next issue, when the car gets up to 40mph, the slightest amount of throttle will initiate a audible whirring noise, almost like a whine, it continues to happen until 50mph where it stops. Without any throttle it is inaudible, the tiniest dab of throttle and it reappears. It happens irregardless of which gear it is in, it's the speed that brings this noise out.

Some googling suggests the central diff bearings could be at fault? How likely does this sound? Is it possible it's the rear diff but the sound is presenting itself upfront? I might change the rear diff oil, as it looks a very easy job to do on the driveway at the weekend. But if it's the front or central diff, they share fluid with the transmission correct?

Are there any other suggestions on what could be causing this noise?

Any help would be greatly appreciated.

Thanks

Mike

Change the diff and transmission oil first. Then report back.

[MDMA .]

TEKNOPUG said:

Change the diff and transmission oil first. Then report back.

as above. top tip, remove the rear diff fill hole before undoing the drain plug. if it is like the one on my Legacy, if you cant remove the top plug, your are knackered if you drain the oil out of first as you cant get it back in ! don't over-fill the gearbox too.

[mikejbry]

Thank you, I'll give it a go this weekend, shouldn't cause too muh difficulty, assuming the drain bolts aren't seized!

Googling shows approx 0.8l for the rear diff, and 3.5l for the gearbox, sound correct? I'll obviously keep checking the fill level on the gearbox. With the diff do I fill until it trys to come out the fill port? (Read on one forum thats what you do)!

Cheers
Mike

[MDMA .]

mikejbry said:

Thank you, I'll give it a go this weekend, shouldn't cause too muh difficulty, assuming the drain bolts aren't seized!

Googling shows approx 0.8l for the rear diff, and 3.5l for the gearbox, sound correct? I'll obviously keep checking the fill level on the gearbox. With the diff do I fill until it trys to come out the fill port? (Read on one forum thats what you do)!

Cheers
Mike

good site is Millers. type your reg in and it gives you the oil type and quantity. looking at the above, exactly the same quantity as the Legacy. 0.8L for the rear diff and 3.5L for the gearbox. rear diff can be filled to the top, you cant overfill it. but the gearbox, only put in the correct amount. do NOT overfill !

[mikejbry]

Ok changed the rear diff oil and no change, I'll try to get around to the gearbox next weekend. I could only see one drain plug under the car, is there a desperate sump for the front or central diff?

Cheers
Mike

[CaptainSlow]

The front diff and gearbox are combined so only one drain plug.

For future reference, be careful of over-tightening the drain plug on the rear diff...very easy to strip the thread.

[mikejbry]

Ok, I am replacing the gearbox with a used one from a 65k mile car. This will sort the issue.

I want to stick a new clutch in while the box is out, any recommendations?

Its only a family car so cheaper the better, no need to upgrade performance etc, just a reliable and cheap clutch. ECP want near £150 for a clutch which seems over the top.

What diameter is the one I require? Any places to recommend sourcing one?

Cheers