Rear Diff Failure on Audi A4 (B7) 2.0TFSI Quattro 68k Miles

Jimmycooker

Hi,

I have a problem.

I sent my car to the audi dealership for a timing belt change.

They said that the car also needed new brake discs / pads and rear differential oil change.

After around 150 - 200 miles a noise developed from the back of the car when i accelerated and it got rapidly worse to the point that i couldn't hear my passenger and i could feel the car pulling back at low speed.

I assumed that one of the following had happened:

a.) the garage forgot to fill the rear diff with oil
b.) they used the wrong oil
c.) they didnt use enough oil
d.) they forgot to refill with oil and drove the car before realizing and then filled it after doing damage.

I therefore asked if i could be there when they drained the rear diff. 0.5L of oil came out of the diff. The garage said that this diff takes 0.9L and that if i had waited / if they had turned the diff the remaining oil would have come out.

They said that the report showed that 2 x 0.5L tubes of oil had been used to fill the diff and the mechanic who did the job said he didn't spill any / have any left over.

The oil that came out was black / dark grey, it looked old.

Can you tell me

1.) How common is it for rear diffs to go in these cars at 68k miles?
2.) Am i right to assume this fault has developed because of the garages intervention?
3.) Would turning the diff release more oil from the axle?
4.) Have they under filled the axle and would this result in differential failure?

They aren't accepting responsibility for this, what could have happened, its too much of a coincidence isnt it that this has happened after an intervention.... any advice on how to proceed / how to deal with the garage would be greatly appreciated.

Thanks,
James.

Anan1

I think you need to speak to a solicitor.

mullingar

Jimmycooker wrote: »

.............I therefore asked if i could be there when they drained the rear diff. 0.5L of oil came out of the diff. The garage said that this diff takes 0.9L and that if i had waited / if they had turned the diff the remaining oil would have come out.

I therefore asked if i could be there when they drained the rear diff. 0.5L of oil came out of the diff. The garage said that this diff takes 0.9L and that if i had waited / if they had turned the diff the remaining oil would have come out.

They said that the report showed that 2 x 0.5L tubes of oil had been used to fill the diff and the mechanic who did the job said he didn't spill any / have any left over.

Sounds like complete BS to me.

Diffs usually have 2 openings, one to drain and the other to fill. The fill one is purposely positioned to not allow overfilling as it pours out of the filling hole.

I would get them to refill it, then empty it. You will see your full 0.9L. The twisting the diff etc to completely empty it will only milk out another 0.05L-0.10L max.

Either:
1. They only half filled it
2. Never tightened the drain

antiskeptic

Jimmycooker wrote: »

Hi,

I have a problem.

I sent my car to the audi dealership for a timing belt change.

They said that the car also needed new brake discs / pads and rear differential oil change.

After around 150 - 200 miles a noise developed from the back of the car when i accelerated and it got rapidly worse to the point that i couldn't hear my passenger and i could feel the car pulling back at low speed.

I assumed that one of the following had happened:

a.) the garage forgot to fill the rear diff with oil
b.) they used the wrong oil
c.) they didnt use enough oil
d.) they forgot to refill with oil and drove the car before realizing and then filled it after doing damage.

I therefore asked if i could be there when they drained the rear diff. 0.5L of oil came out of the diff. The garage said that this diff takes 0.9L and that if i had waited / if they had turned the diff the remaining oil would have come out.

They said that the report showed that 2 x 0.5L tubes of oil had been used to fill the diff and the mechanic who did the job said he didn't spill any / have any left over.

The oil that came out was black / dark grey, it looked old.

Can you tell me

1.) How common is it for rear diffs to go in these cars at 68k miles?
2.) Am i right to assume this fault has developed because of the garages intervention?
3.) Would turning the diff release more oil from the axle?
4.) Have they under filled the axle and would this result in differential failure?

They aren't accepting responsibility for this, what could have happened, its too much of a coincidence isnt it that this has happened after an intervention.... any advice on how to proceed / how to deal with the garage would be greatly appreciated.

Thanks,
James.

First of all, sorry for your woes. I can't imagine this would be a cheap repair. A few thoughts:

1) A differential isn't like an engine. An engine without oil would be quickly wrecked if ran without oil / seriously low level of oil. Gearboxes/diffs and the like, if wetted with oil wouldn't fail in the catastrophically quick manner yours has. At least, I seriously doubt it.

I worked in a motorcycle garage which forgot to replace the drained oil in a brand new bikes gearbox. 2 weeks later an it was fine when we stripped it - even though we had to give the naturally dubious owner a brand new replacement bike.


2) Gear type assemblies are designed to run part immersed in oil - the rotating action of the gears flings oil around the place and so provides lubrication to all corners. My feeling (although I wouldn't stake my life on it) is that even with a lower than ideal level, you wouldn't suffer fast/catastrophic levels of damage through lubrication starvation. A faster rate of wear perhaps but not such failure.

3) It would be interesting to see if that 0.9L figure was the first fill quantity. That is, the quantity of oil required to fill a new, dry diff. If so, the drain amount would be a fair deal less than that since some of the oil would tend to get retained in nooks and crannies within the diff casing. If the 0.9L is quoted as the drain amount during servicing (or the dry fill amount is something like 1.1L then I'd go back and let them demonstrate what their talking about: drain the unit and then "turn whatever needs to be turned" to get another 0.4L out. I'd be cautiously suspicious of this claim.

4) Even if they did forget to fill the diff, I just don't see how major damage could have been caused in the mileage covered by the kind of brief road tests a garage might carry out after a service.

Nissan doctor

antiskeptic wrote: »

1) A differential isn't like an engine. An engine without oil would be quickly wrecked if ran without oil / seriously low level of oil. Gearboxes/diffs and the like, if wetted with oil wouldn't fail in the catastrophically quick manner yours has. At least, I seriously doubt it.

Maybe with straight open diffs but Haldex and other viscous type diffs use oil/oil pressure to operate.

Jimmycooker

Not what i wanted to hear antiskeptic, but thanks...

Jimmycooker

So do ye think that .5L coming out of the car is low? As far as i remember there was a nut on the bottom of the diff that they drained from and a nut on the side which he stuck his finger into first before he drained from the bottom. Where is the .4L supposed to be in the casing if it hasn't settled to the bottom where the opening is? Is this amount of under filling responsible for the problem do you think?

antiskeptic

Jimmycooker wrote: »

Not what i wanted to hear antiskeptic, but thanks...

See Nissan doctors comment above.

I'm supposing a straight forward differential with some gears and bearing lubricated by oil sloshing around the place. Perhaps the A4 has something far higher tech.

Why not go the route of establishing with them that "turning the diff" after the initial drain will produce another 0.4L. That smells a little whiffy and if the 0.4L doesn't turn up, the ball is firmly in their court.

langdang

Think the rear diff on that A4 is just a standard rear diff. (with funky electronics to mimic locking the diff via the pulsing individual brakes)
The centre diff is torsen, so not hydraulic either (in my limited understanding of these things)

walus

If the diff worked perfect for 68k miles and only lasted 200 miles after the oil change it clearly shows to me where the problem is. I can not imagine that gear oil in the differential would be so thick so almost half of the amount would not drain. Surely that can not be right. 10% of its quantity - maybe, but not almost 50%! The differential was wrecked because it was not lubricated properly - that is the reason. Why it was not is a question you should ask the dealer.

firefly08

Think the rear diff on that A4 is just a standard rear diff. (with funky electronics to mimic locking the diff via the pulsing individual brakes)
The centre diff is torsen, so not hydraulic either (in my limited understanding of these things)

Yep I think that's right. I think only the A3 used the viscous system, so it's normally FWD and the power only goes to the back when needed.

langdang

firefly08 wrote: »

Yep I think that's right. I think only the A3 used the viscous system, so it's normally FWD and the power only goes to the back when needed.

First gen quattro TTs were haldex type diff too.

Jimmycooker

So if .5l or .6l came out when drained on the flat, there couldn't be a remaining .4 or .3L in there? and this underfilling would be enough to wreck the diff?

mickdw

Fill it now ideally supervised by engineer working for you, then drain it. If significantly more than 0.5L comes out (.8 to .9L), its 100% certain that they only half filled it. Then its solicitor time if they wont play ball

EPM

You need an independent report on this pronto.

Matt Simis

Its possible that they didnt tighten one of the holes to fill/drain too... likely the fill hole as it wasnt totally drained. When the diff heated up and moved about it sprayed out a significant amount of Oil.

While you didnt cause it, you should have stopped driving it the moment that noise (of the diff gears shredding themselves) was heard. Waiting till passenger's compliants were drowned out by the racket was far, far too long.


I would not consider 68k even remotely high enough mileage for diff failure through wear and tear. 200miles on the diff oil shouldnt be enough to turn it black either. However the black bits are likely metal shavings.. find out exactly what oil they used.

Jimmycooker

Lads,

They say this is a mechanical diff and that .4L would be held up in the gears.

They want 3000 to fix it...

Desperately need some advice on this now...

EPM

You need to get the car independently accessed. The report from this will either give you something to beat them with or tell you if there was another issue.

Jimmycooker

Any ideas who would be a good garage to take it to in fermoy / cork?

mickdw

Get an Engineer.
They are walking all over you. They say they put 0.9L into it. If 0.9L is the oil change volume, 0.9L must come out at service.

Why not pay them to carry out a supervised oil change again on the diff. If the car is still driving (badly) and the diff is not siezed, the oil volumes should work out properly.
According to the dealer, .5l came out. 0.5L should fill it completely from its current state if that is the case?

Jimmycooker

What kind of engineer and from where? what garage would you suggest?

Jimmycooker

What info should i ask them for that i might be able to use against them.

1.) Copy of the service report
2.) Oil type used
3.) Colour of new oil (as the oil that came out looked black)
4.) Amount of oil filled into diff
5.) Copy of the procedure for changing the oil
6.) I saw a .5L of oil come out of the car, have they done a test to see if the same thing happens when it is filled.
7.) A copy of the procedure they use (if they heat the oil / run the car through the gears etc to change the oil.

Anything else??

The engineer / independent assessor idea is all well and good but trying to find one in a hurry might be a challenge. I'd give Cork gearbox centre http://www.corkgearbox.com/ a ring, they do everything by the book to manufacturers recommendations and are quite anal about it (rightly so of course), they'd more than likely know lots more about difs etc than folks in Blackwater Motors, now BM may well be good customers of theirs of course.........
Worst case scenario they might be cheaper than €3000 and actually diagnose the issue.

Jimmycooker

Jimmycooker wrote: »

................
6.) I saw a .5L of oil come out of the car, have they done a test to see if the same thing happens when it is filled...............

I'd be asking them if only .5l came out how come the chap who did the work used 2 x 0.5l containers of it and had none left over, because if they are correct in saying 0.4l is held in the gears than you can put 1l in on top of that and only 0.5 comes out, if it's held in the gears it would have been held in the gears when they drained it some weeks back too.

Nissan doctor

No oil is held up in the gears.

As has been said, if they say they filled it with 0.9/1.0L then they had to have drained that amount.....meaning the same amount should have come out when they drained it in front of you.

Jimmycooker

Ok thanks...gonna flat bed it out of there to another garage for a look

mickdw

Yes I would keep everything in writing too.
Get confirmation from them of type and volume of oil used as well as confirmation of the volume drained in your presence and their reason for the volume of oil being drained being much lower than the amount put in at service.
I would tie them to these facts in writing first.
Any experiments then with refilling and draining will hopefully leave them up sh1t creak.

EPM

Jimmycooker wrote: »

Ok thanks...gonna flat bed it out of there to another garage for a look

You could give autowerks in Midleton a shout.

Jimmycooker

My draft email to audi:

In the mean time can you supply me with the following info:

1.) Copy of the service report with all the work that was carried out at the time of the timing belt changed.

2.) Copy of the order / form showing the type of oil used on that date for the rear diff oil change.

3.) Copy of the report that states exactly how much oil was drained and how much oil was replaced.

4.) Colour of the new oil and confirmation that the old oil was black in colour when it came out.

5.) Copy of the procedure follwed for draining and filling the oil

6.) Can you confirm how much oil this rear diff should take.

A.) .9L into a new rear diff without any oil

B.) .9L into a rear diff that has been drained stationary

C.) .9L into a rear diff that has been drained from the car while running (on the lift)

Can you confirm that you drained the rear diff in my presence and give me as much detail as to why the only .5L came out (See attached photo) and not the expected .9L.

Anything else?

tossy

If it was me i'd get an independent assessment carried out and hit them with that report straight away to show them you mean business.

Autowerks is a good recommendation as the first thing Audi are going to question is the validity of the assessor and no one question autowerks reputation.

I would also follow the e mail up with a call,and in the mean time maybe even while it was being assessed i would consult legal advice - sorry OP but haven't read thread top to bottom so maybe you have done this?

mickdw

Here is some info I cpied from my Audi workshop manual.
There is no special instructions about spinning anything to drain the diff etc. There is a fill hole and the oil should spill out there when full.
Oil type & container size is detailed also.
Do you have an invoice with the part number for the gear oil listed. This could be interessting as the 0.5L can & 1L can have different part numbers as you will see on attached diagram.




In your case, anything over 0.5L added now should immediately start to run out the fill hole.
I would really get an Engineer to inspect any of these procedures though. Id get one form a fair distance away too. It will cost you 2 to 3 hundred to do that but if it means you can prove the fault is with the garage, it will be money well spent and Im sure they would have to pay that too in the end.