grinding back end

**matthew bond** · 20-04-2008,05:29 PM

hi all, this is my 1st time on this forum, wondered if any one can help me.

i have an '02 a4, 2.5 tdi quattro 180 avant. have had it for 18 months and it has recently developed a nasty grinding noise that comes from the back end when pulling away on full lock. it feels like the car has a limited slip diff. somebody had suggested that it maybe something to do with a rear calliper binding? any help on this would be great.

thanks alot.

**willster** · 21-04-2008,09:20 AM

Originally Posted by matthew bond

hi all, this is my 1st time on this forum, wondered if any one can help me.

i have an '02 a4, 2.5 tdi quattro 180 avant. have had it for 18 months and it has recently developed a nasty grinding noise that comes from the back end when pulling away on full lock. it feels like the car has a limited slip diff. somebody had suggested that it maybe something to do with a rear calliper binding? any help on this would be great.

thanks alot.

im afraid i cant help with any answers although mine does exactly the same, although its more of a thumping when pulling away at full lock. I know Quattros are prone to some noise when turning on full lock due to the 4wd system but mine doesnt sound to normal or healthy. Im just going to ignore it! my car has been road tested by Audi and they never mentioned it ,and there usually very quick to diagnose any slight problems if its going to get them some expensive work!

**matthew bond** · 21-04-2008,10:51 AM

Originally Posted by willster

im afraid i cant help with any answers although mine does exactly the same, although its more of a thumping when pulling away at full lock. I know Quattros are prone to some noise when turning on full lock due to the 4wd system but mine doesnt sound to normal or healthy. Im just going to ignore it! my car has been road tested by Audi and they never mentioned it ,and there usually very quick to diagnose any slight problems if its going to get them some expensive work!

hiya, cheers for reply. mine could be described as thumping too. like you say it doesnt sound healthy. my mate has 3.2 quattro and doesnt have prob. mite take mine to local audi and see what their response is.

**willster** · 21-04-2008,12:15 PM

all i can say is just dont take their word as gospel, you would think a reputable company like Audi wouldnt recomend work that doesnt need doing but ive had two bad experiences at Audi.they told me my head gasket had gone which is utter rubbish,im not losing coolant or oil,and there is now no smoke after disconecting my EGR .If you have any other problems with your engine or anything give us a shot, i have encountered a lot of the common ones with mine,like the power loss,and have fixed them at home myself.Also if you could let me know what Audi say i would be gratefull to get their opinion, even if i dont agree!

**crugiwan** · 25-04-2008,08:06 PM

I have exactly the same problem on an 02 2.5TDI Quattro Sport.

Have you found out what the problem is. I had a local mechanic have a look and he has said that the bushes look fine but there is some play in the rear diff and with it off the ground he can get it to make the noise by grabbing the drive shaft and turning quickly but he said keep driving until it gets worse and then think of replacing the rear diff.

**willster** · 25-04-2008,09:13 PM

i havent solved it yet but the rear diff thing sounds preety likely. did the mechanic give you an indication of cost of replacing rear diff?

**matthew bond** · 29-04-2008,07:14 PM

how many miles has have your cars done? mine has done just over 80k, surely an audi diff shouldnt be on its way out that soon

**A4_3.0_TDI** · 06-04-2009,08:52 PM

This thread is a year old - so I’m wondering how you got on?
I was going to ask a very similar question. A4 B7 3.0 TDI Quattro Auto 88k miles.
Crunching noise from the back end - during slow speed manoeuvring.
(i.e. left turn into a parking spot)
Its very in-frequent and NOT repeatable, so Audi and local garage can't diagnose it.
CV's Boots and Bushes all checked out OK.
I was honoured enough to see a Jaguar Diff tested to destruction at Visteon's factory. If the oils missing it'll seize straight of the production line.

**jmini23** · 06-04-2009,09:35 PM

Hi i'm new on the forum and just bought my first audi a couple of months ago

Very interesting -my 54reg quattro 3l 52k miles avant suffers from exactly this. Seems like it's a quirk of the quattro - guess you can't easily top up or change the diff oil?

**A4_3.0_TDI** · 07-04-2009,04:12 PM

Hi Jmini
Didn't mean to imply it’s an oil problem, and stress you out.
Just Mathews comment above, about expecting more than 80k from a diff.
(They should pretty much go on forever.)
It just reminded me of a trip to Visteon in Swansea, were they make a lot of the Ford group parts i.e. Brake assemblies and gearboxes etc.
And I witnessed a destruction test on a Jaguar XK differential. Big explosion proof perspex container hooked up to a drive chain. Drained it of oil and ran it up to full speed - very undramatic seizing followed by a wisp of white smoke - with all the safety precautions, somehow I expected a little more.
Back to the point
- If the mechanics aren’t worried about a little noise
- Then neither am I
I was just wondering if these guys had got to the bottom of things.