S3 8l whining in the back, while decelerating

[Šubler]

Hi guys,

run into new/old problem...
So, lets say im driving at 100km/h, and I let the gas pedal off, there is whining noise coming from the rear diff i believe.
It got worse when i changed the oil in the diff, it took about 1L. Is it possible that the level of oil is to low now? Since the only thing i changed was oil and its worse now.

Ive read alot threads with similar problems but didnt find one like mine, i suppose the diff is on its way out? worn gears or bearings?

Sry for my bad English.

 

[desertstorm]

What oil did you put in the diff?. Have you checked/ changed the haldex oil.

 

[Stuart B]

the only times I have had this it turned out to be

1. rear wishbones rose joints ceased - and that broke a tie bar and wheel not pointing straight.
2. rear tyre pressures too low - slow punctures (on two different occasions)

as recently as last month.

it feels fine on accelerating but like a dentist drill when rolling on engine braking.

I had changed the rear diff oil and haldex oil previously trying to address it.

 

[Šubler]

I used fuchs sintpoid 75w-85, as i have been told. I will try to use thicker oil and an Xado additive this week.

Haldex needs change in 1k km so looking after this aswell.

Will check prassure in tyres, car was parked on lift for 2 months...

 

[JonnyDerv]

Sounds exactly the same as when my rear diff **** itself

 

[mephisto]

Hi there i had the same on my S3 8P. It was the rear diff, a replacement (2nd hand off ebay) one fixed it im afraid

 

[IPG]

i think i have the same thing happening - luckily i have some spares but just need to get the time to do the job

 

[Šubler]

Problem on mine was the rear left tire, it was low on pressure, way lower than the right one... I pumped them to 2.5bar both and the whine is nearly gone, i can still hear it when radio is turned off but its way better.

 

[IPG]

Squeezing this in before the sun went down



Back part of exhaust off


Get these off to swing the rear sway bar out the way to access all the bolts needed to remove the diff from the back


Scavenging haldex oil


Hopefully this fixes the whiney sound. No one likes a whiner.

 

[Šubler]

Hi,
strange thing happend today, as you can see in this thread, i solved my whining problems, but today they have reappeared, i changed my wheel set and whine in back, as soon as wheels were changed and i went for a test drive the whine was back. Will try to switch back to old set and see if the whine will be there or not.

I have 2 different pairs of tires on new wheels, one pair is in better condition, manufacturers are also different but the size is the same, is it possible that this is making problems?

 

[Tj 0785]

Are the tyres on the right way?

 

[Stuart B]

the only times I have had this it turned out to be

1. rear wishbones rose joints ceased - and that broke a tie bar and wheel not pointing straight.
2. rear tyre pressures too low - slow punctures (on two different occasions)

as recently as last month.

it feels fine on accelerating but like a dentist drill when rolling on engine braking.

I had changed the rear diff oil and haldex oil previously trying to address it.

You have ruled out 1 above. What are the tyre pressures 32psi ?

 

[Šubler]

Hi,

I switched back pair to front and front to back, whine is gone!

 

[Stuart B]

That's a lot cheaper than changing a whole heap of parts and changing the diff and haldex oil/filter, paying for alignment (even though you cant change the rear)