Rear diff/haldex total failure after oil change (S3 8P 2008)

berisen · Sep 3, 2020

Last night I had a major failure to the rear differential/haldex and I'm trying to figure out what went wrong and thought that maybe someone could help me that's been in the same situation.

Anyway, two dags ago it all started with me handing the car to a local shop for the yearly service with change of oil, filters, fluids etc but also the oil for the haldex. So far so good.

Left the shop and I drove home and on the highway at around 60 mph I noticed a slight whining noise from the rear, very subtile and it disappeared at like 65-70 and then it was gone. Didn't think much more of it at the moment and also took it for a drive later that night without hearing anything strange at all and it drove just like it should.

Yesterday I went for a little longer trip (about 60 miles) and everything went great until the way home. Only got about 10 minutes in before the whining noise really picked up and it shortly followed by a rumbling noise and then a loud bang followed by total failure of the rear diff and oil on the street. :sadlike:

Obviously something was not done correctly at the shop when changing the haldex oil but what could cause this catastrophic outcome? Draining the diff instead of the haldex by mystake? Filling the diff with haldex oil instead of gear oil? :crying:

I know that the fill/drain plugs of the haldex/diff is pretty close so maybe they just drained the wrong stuff?

I find it very hard to believe that it's just a coincidence that on the day after someone's been working on the diff-unit the whole thing just pretty much explodes after 2-3 hours of driving.

Any thoughts about this? :bye:

NHN · Sep 3, 2020

It's not a coincidence, clearly linked, so tell them they need to fix it as it was fine before it was brought in.

I would jack it up & check the plugs to see which have fresh marks on aswell.

Paul McGrath’s Knees · Sep 3, 2020

I agree with the above. However,I guess you are about to find out,if your mechanic is an honourable guy or not. Have you been using them for a while? I hope it all goes well for you,but you won’t be the first person I’ve heard who’s been left in the lurch when the mechanic comes out with the “it was fine when it left here” response

Good luck

K96 · Sep 3, 2020

Bring it back and let them fix it. Obviously done something wrong so they need to correct their mistake.

Sent from my SM-G973F using Tapatalk

berisen · Sep 3, 2020

I will have another mechanic in that town to have a look at it to document what has been done in the previous shop that led to this failure and hopefully there wont be discussion about it.. to me it all looks very obvious. I mean, it has to be related to their work? Why would it just break totally like that otherwise?

Is there any other mistakes in the oil change work that they can have done that causes this kind of failure?

ab1702 · Sep 3, 2020

My wild guess is that they’ve drained the oil out of the rear diff and filled it back up with haldex oil which is a totally different thing. I reckon they haven’t touched the haldex.

Daveyonthemove · Sep 4, 2020

Certainly looks like the Haldex oil was used in the rear Diff, there isn't really any other explanation for it.
Hope you get it sorted quickly at his expense. There's always the small claims courts if he becomes obstructive.

linfords81 · Sep 4, 2020

if its the same as the skoda haldex which it probably is they have drained the wrong oil, there is a drain plug which looks like haldex drain but isnt we have had a few in from other garages which have done this and blown the haldex units up

Btm · Sep 4, 2020

Wow what a coincidence I had my Haldex serviced this week and the exact same thing happened to my diff! WTF the mechanic said it’s common, please help

berisen · Sep 4, 2020

linfords81 said:
if its the same as the skoda haldex which it probably is they have drained the wrong oil, there is a drain plug which looks like haldex drain but isnt we have had a few in from other garages which have done this and blown the haldex units up

What did you had to change on the ones that came in with this issue? Is it "just" the haldex unit (0AV 525 010 K ?) or is more stuff damaged when the unit blows up? Still waiting for a report from the mechanics about what kind of damage there is but I can only assume that at least the whole haldex unit is trash and needs to be replaced.

I guess it's this one that needs replacement?

linfords81 · Sep 4, 2020

yeah just replace the full unit as it normally cracks the casing

berisen · Sep 4, 2020

linfords81 said:
yeah just replace the full unit as it normally cracks the casing

When I look for used parts it's a bit messy with a lot of different serial numbers to look into. Do you know if I need exactly the same model or can I use a unit from a A3 8P from a different year (like 2007-2010) or does it need to be specifically from a 2008 S3?

linfords81 · Sep 4, 2020

not 100% to be honest we let parts sort that bit out lol can you see the 2 drain plugs with copper washers on? do they look like they have been off recently

berisen · Sep 4, 2020

linfords81 said:
not 100% to be honest we let parts sort that bit out lol can you see the 2 drain plugs with copper washers on? do they look like they have been off recently

Unfortunately the car is still 60 miles away and i'm waiting for mechanics in that town to call and tell me about their findings. Will then contact the shop that did the service job and explain the whole thing and hopefully they will sort it out. But from the replies in this thread it sounds pretty obvious that the wrong drain plug have been off.

berisen · Sep 4, 2020

Good news, it looks like it will be sorted out. They will replace the unit since it had a big crack through the body. I never got any explanation about what exactly caused it but from what i've read in this thread it feels like some sort of mistake when draining.

ab1702 · Sep 4, 2020

berisen said:
Good news, it looks like it will be sorted out. They will replace the unit since it had a big crack through the body. I never got any explanation about what exactly caused it but from what i've read in this thread it feels like some sort of mistake when draining.

The things you’re talking about above in this thread are wrong. The picture you added this morning is the rear differential. A haldex unit is a totally different part which attaches to the rear diff to engage the 4wd for the rear wheels.
If the picture above is what needs replacing then the garage have worked on the wrong part, they shouldn’t have touched that as it’s a totally separate thing to the haldex.
If they fix this for you buy replacing the rear diff then after it’s done you will still need to get the haldex serviced as that obviously wasn’t done in the first place because they didn’t know what they were doing. If you do decide to go ahead after this is fixed and get the haldex serviced then you need to change the haldex filter aswell otherwise it’s pointless just changing the haldex oil. Depending on the age of your car though you can’t always get the haldex filter from Audi so you have to get it separate. There’s a website called haldex repairs that sells all the haldex equipment.
Don’t let what has happened put you off getting the haldex serviced though because if you do then your haldex will probably fail and you’ll lose 4wd. You then have to get the haldex pump replaced and then also change the haldex oil and filter.

berisen · Sep 4, 2020

ab1702 said:
The things you’re talking about above in this thread are wrong. The picture you added this morning is the rear differential. A haldex unit is a totally different part which attaches to the rear diff to engage the 4wd for the rear wheels.
If the picture above is what needs replacing then the garage have worked on the wrong part, they shouldn’t have touched that as it’s a totally separate thing to the haldex.
If they fix this for you buy replacing the rear diff then after it’s done you will still need to get the haldex serviced as that obviously wasn’t done in the first place because they didn’t know what they were doing. If you do decide to go ahead after this is fixed and get the haldex serviced then you need to change the haldex filter aswell otherwise it’s pointless just changing the haldex oil. Depending on the age of your car though you can’t always get the haldex filter from Audi so you have to get it separate. There’s a website called haldex repairs that sells all the haldex equipment.
Don’t let what has happened put you off getting the haldex serviced though because if you do then your haldex will probably fail and you’ll lose 4wd. You then have to get the haldex pump replaced and then also change the haldex oil and filter.

Thank you for the reply. Good point there, I need to make sure that it's serviced before clearing it.

I talked to the shop that looked at it today and there was a crack in both the differential and in the Haldex unit so things must have been pretty rough. If I look at this image it's pretty easy to losen the wrong bolt here I assume and I think that is what has happened.

ab1702 · Sep 4, 2020

berisen said:
Thank you for the reply. Good point there, I need to make sure that it's serviced before clearing it.

I talked to the shop that looked at it today and there was a crack in both the differential and in the Haldex unit so things must have been pretty rough. If I look at this image it's pretty easy to losen the wrong bolt here I assume and I think that is what has happened.

I think you’re being too kind to the garage that’s caused this. They obviously didn’t know what they were doing or it wouldn’t have happened, in which case they should have looked up what to do before doing it.
I’m no mechanic and even I know by looking at them from underneath that they are totally separate things and that the haldex is on the left and the diff is on the right.
If they’re putting it right though then fair play to them as it’ll cost them a bit of money to replace a haldex unit and a rear diff.

Btm · Sep 4, 2020

berisen said:
Good news, it looks like it will be sorted out. They will replace the unit since it had a big crack through the body. I never got any explanation about what exactly caused it but from what i've read in this thread it feels like some sort of mistake when draining.

Please try to get an explanation and share it with us so others And myself know what to look out for...and have something to go by, as I said before, the same happened to me but my mechanic will not own up to it being anything to do with the haldex service he did and just told me it’s a coincidence that my diff shat itself because it’s common for them to do so I don’t buy it but he is supposed to be an expert! Btw my Audi is an 09 A3 Quattro with 70,000kms and has been babied it’s whole life.

Paul McGrath’s Knees · Sep 5, 2020

Good news that they are going to fix your car

Pity you have had to go thru this experience,let’s hope it’s all good when you get it back

Btm · Sep 6, 2020

Can anyone help me? The mechanic that serviced my haldex is denying responsibility

samuelh_888 · Sep 6, 2020

Btm said:
Can anyone help me? The mechanic that serviced my haldex is denying responsibility

I can’t help.

You need to go to a specialist and get an expert opinion. Based on their advice you have the small claims court process available.

You need those alternative opinions which will code you money - which you may be able to claim back.

Btm · Sep 7, 2020

samuelh_888 said:
I can’t help.

You need to go to a specialist and get an expert opinion. Based on their advice you have the small claims court process available.

You need those alternative opinions which will code you money - which you may be able to claim back.

Thanks, I was hoping someone with good knowledge was on here that could verify that the mechanic would have done something wrong and that it’s unlikely that my differential would have just failed out of the blue by coincidence just from experience.

nluk100 · Sep 7, 2020

Btm said:
Thanks, I was hoping someone with good knowledge was on here that could verify that the mechanic would have done something wrong and that it’s unlikely that my differential would have just failed out of the blue by coincidence just from experience.

Get another mechanic to inspect it and record what's been touched/changed. Then advise the garage of the findings and that you're planning on taking them to court. And see what they say.

berisen · Sep 11, 2020

A little update. Finally I got the car back and they actually replaced the whole unit with differential/haldex since there was a big crack running through the whole body. Still I haven't got any real explanations about what caused it all and I'm not sure the shop knows either from what it looks like. They say that changing the haldex oil is something that they've done many times before. This time something clearly gone wrong though.

I will try to get some more information about it but right now I'm just happy that it's all sorted.

Btw, these kind of repairs is insanely expensive if done at an Audi dealer. If new parts were to be used, it would cost something between £6200 and £6600 they said over at that place the car was first towed to. Sounds ridiculous really. I mean, with a little luck I might get like £12-13k for the whole car

@Btm Sorry to hear that they are being like that to you. From your story it sure sounds like exactly what's happened to my car. I mean, if you never had any issues with any weird noises and such from the rear diff, why would it suddenly just give up right after they "changed oil" to it? I think you should really try to make them see the obvious here and make them fix their own mistake.

samuelh_888 · Sep 11, 2020

berisen said:
If new parts were to be used, it would cost something between £6200 and £6600 they said over at that place the car was first towed to. Sounds ridiculous really. I mean, with a little luck I might get like £12-13k for the whole car

A new diff & haldex won’t double the price of the car unfortunately - just makes for a lucky buyer.

At least they sorted it all out.

Rear diff/haldex total failure after oil change (S3 8P 2008)

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