S3 diff problem

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curtis11

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Hi , have a 01 s3 it's done 94k with full history.
The rear end is whining it's balls off when off the throttle
I have changed to different wheels to rule that out but was pretty sure it's diff or haldex .
Is there any point of changing the haldex oil and diff oil or just rip it out and get it looked at ?
Any help will be much appreciated
Cheers
curtis11
 
Ok just took out the haldex fuse and the noise has completely stopped , is it ******?
 
me thinks it must be an electrical issue as your root cause if you have removed the fuse and the problems goes away. Haldex controller ? or any other electrical gadget disabled by removing the fuse.
 
audi upgrades
I have code 65535 so I recon it could be the controller , what you think ?
 
Did you hear the controller operating in the second part of the test? it's quite hard to hear as the pumps already running from the first part.
 
No I didn't hear anything different , was lying with my head down by the ground and couldn't hear any difference
 
It really is quite hard to hear as it's only a split second you hear the controller operate and what with the noise of the pump whirring away, might be worth unplugging the pump from the controller so you can hear if it's working or not.
 
No sham , not yet , latest is that I checked the controller plugs for corrosion but they were mint , I am trying to borrow a controller off a guy I know with a r32 to see if it makes a difference , the car sounds terrible , like the diff is completely fukt then pull the fuse and it dll goes away , weird.....
 
Have you checked the oil in the rear transaxle diff housing ?
 
ps

I don't mean the haldex oil, the diff behind that

The rear pinion gears can make alot of noise when damaged
 
guys,. he states when he removes the haldex fuse problem goes away. The clue is there in your face.
 
Haldex and rear diff oil has been replaced , think it's the controller stuck in permanent 4wd
 
If the haldex controller can only trigger and adjust the pump pressure

It does this via a small actuator pump

imho if the unit had somehow decided to set the clutch to full engagement, this in itself wouldn't cause adverse noise

Fooling a haldex unit into full pressure is one method of tuning these units: Powertrack Insert

imho tuffty is probably on the money

I'd get the car on a scissor type post ramp, so you can run the car with the wheels free
The controller should set the clutch to full pressure
You can then test disengagement by gently pulling on the handbrake
Under VAG software the haldex system should release all clutch pressure on any form of braking
 
curtis11 said:
Pulling the hsndbrske on doesn't make a difference to the noise
Click to expand...


With your car up in the air, in 1st gear and obviously with the wheels being able to more freely?
Pretty sure that's what snow_muncher was advising to do above
 
Yes I know what your saying but if I pull the fuse the noise goes so pulling the handbrake should do the same as pulling the fuse?
 
Last edited:
Pulling the fuse cuts power to both the controller unit and the main pump together

Putting the car on ramp mean you can test under controlled conditions & have a listen to the haldex unit up close
 
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Ok , will see if I can get it on a ramp this week, can it be anything else other than pump or controller ?
Cheers
 
Ok , handbrake on does deactivate the 4wd, sooooooo........ Now what
 
To my mind this points to your controller being ok

The charge pump has its own plug connector, you could now trying to disconnect this

If you've got no whine when its disconnected then to my mind at least, then a new/recond charge pump would be the next step
 
Ok unplugged the pump and the noise is gone as I suspected , how could the pump cause the rear end to whine like a mammerjammer ?
 
bearings on its electric motor burning out maybe

At least there seems to be a reasonable supply of 2nd parts
 
I can't see it being the noise of the motor , much too loud , goin to pull the rear end out and get it checked
 
curtis just change the pump and problem gone i did it today had the same noise as you and all is well no more noise
 
No way , mine sounds like gears grinding on deceleration , is yours the same
 
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