Whining noise under-load.
 

94WRX has a whining noise coming from the front end under load, the noise starts at around 40mph and the pitch seems to change with road speed.. Sounds like a supercharger.. As SOON as you let of the throttle the noise disappears, then if you merely tap the throttle it comes back. There is also no noise when going down the gears, even on a spirited drive.

My first thought is a bearing in the gearbox, but could it be a wheel bearing? Generally I would expect more of a droning noise though.

The only permanent 4x4's I've regularly driven are off-roaders and they whine at high speed, is this the case with the Impreza?

Cheers in advance for any advice :)

My bugeye has always made a very light whining noise under acceleration, and yes, the noise cuts off as soon as you lift off the throttle pedal. I think it's perfectly normal and nothing to worry about - maybe the air filter or sub-boost turbo noise. Perhaps someone else can shed some light.

mine did similar, it was found out in the end it was down to losing power steering fluid. worthwhile topping this up and checking for leaks where it goes into the rack. Sounded like a touring car, and got progressively worse

Cheers for the replies guys..

When she got the car it had a PAS fluid leak, one of the unions on the rack was loose and it was dripping fluid, the previous owner had a large bottle of fluid in the car and he just topped it up (lazy bastid).. The pump did make some horrible noises when it was low but the leak is fixed now and the level hasnt dropped what so ever.. This is why I mentioned the PAS pump, i'm concerned it might be duff now lol!

At first I thought it might have been and air leak of some sort, but I would expect that to only happen under mid/high throttle conditions.

my wrx 93 jdm does the same m8! soon as it comes on boost you get a wineing sound1 am pretty sure it's the turbo spining up tho! but does sound like a super charger like lol! :wonder:

My 95 wrx does the same and is driving fine.

when I had the problem with the leak, the ps reservoir appeared to have fluid in it, and indeed it registered on the base of the dipstick. However I decided to top it up anyway and was surprised by the amount it took.

Have you got a boost guage ???
You could experiment...watch the boost on acceleration, if you hear the noise when boost goes positive, ie on turbo spool up ...sounds like you have a turbo problem.
And of course when you take your foot off the loud pedal, the boost will drop almost instananeously.

I'm sure about the PAS fluid level, I even topped it up to the brim to be sure ;)

It seem to do it on and off boost :(

The plot thickens! I replaced the track rod ends (getting some wobble under braking) and therefore I adjusted the tracking, I took the car out for a spin just to check there is no more wobble and no pulling; I got up to speed (at the point where the noise gets pretty loud) and I thought i'd see what happens if I depress the clutch and coast.. The noise dissapeared as I came of the throttle then as soon as I depressed the clutch the noise re-appeared? Very strange! Its like when there is no torque being transfered BACK through the gearbox it makes a noise, very strange!

Your saying that the noise happens when the clutch is in? That could be one of the clutch bearings. Thrust bearing or release bearing. Not an expert on clutch and gearbox. Though this might jog someones memory. Whining noises are a ****er to track you usually have to have some idea of what they might be and drive the car around with the windows open for a better listen. Get someone else to drive the car and sit in the passenger side with the window down too. This way you may get a feeling for which side the noise is comming from..;)

It happends if you hold the clutch in at speed and come off the throttle, and its defo road speed related so nothing on the clutch side of the gearbox..

Sounds like its comming from the middle of the car (gearbox) but I might just be assuming that?

I'm no expert on Imprezas but it doesnt sound like a wheel bearing either :(

What BHP you running. I have a mate that took a 94 wagon to 480BHP just to see if he could. It used to whine. The same noise you hear when they have the cameras inside rally cars. He sold the car soon after this so i dont know if the box ever broke. Maybe its just your load thats making the noise?
Im running out of ideas sorry like i said im not good at gearbox stuff.
I would really need to hear the noise and even then I might be cluesless?

Hang on did i ask if the noise goes away under braking?

What makes you think the noise is in the middle can you feel anything in the car?

Its a pretty much standard JDM WRX...

I think I might have cracked it though! Just checked the gearbox oil again and realised the level is about 25mm above the full line, that probably wont help :lol1:

Oh and most rally cars have straight cut boxes which whine like a bitch, but they are supposed to :thumb:

Well i just try to help. I hope its yor oil M8. How did it get so high?

God knows, the previous owner was a complete pleb so he probably just filled it to the top!

there should be a level plug a fill plug and a drain plug. You drain the oil throught the drain. When you fill you remove the level and fill plugs. You fill through the fill hole till it runs out of the level hole. Im sure you know this!

As your aware there is a dipstick at the front, and the "dipstick" (the previous owner) has obviously filled it via this point :lol1:

Or in fact it may have even been the garage that fitted the replacement box (there is an invoice for a recon'ed box and fitment)..

Never the less there is FAR to much oil in there :lol:

Don't drive with your wife in the car.

MY03 does this under hard accel in second/third. Same as deester1 sounds like a rally/touring car gearbox. Does it do it in every gear? You said it happens with the clutch in at speed. Does it do it with the clutch out but in neutral? If so then it won't be a gear issue but might be a diff?

Every gear (well those that you can use over 40 ;) ) and with the clutch in at speed.. Not tried it in neutral actually!

I'm starting to think its a combination of too much oil and maybe an inboard CV joint..

I have diagnosed noises like what you are describing on about 4 different Impreza's and in all cases it was worn bearings in the centre diff 'transfer case' There are 4 ball bearings in there and you will find that the hard surface has flaked off on one of the races. Change all 4 bearings to be safe. If you lift it uo on a two post lift and run it in 4th or 5th and listen with a stethescope, the noise should be easily heard.

Subaru Impreza 2011
 

Any update on this problem and what if anything should be replaced?