Hi all,

 

Bought a 2015 Octavia Scout 1 year ago, 4WD never worked. Thought it had been fixed by a fluid change and a pump strainer clean done by independant garage. Quickly realised it wasn't fixed. Local VW garage removed the pump again and found the fluid to be contaminated again and swarf present. Diagnosis is that the clutch pack had failed. Quoted me for a complete diff assembley £6127 !!

 

There is no noise from the diff so my plan at the moment is to buy a reconditioned Haldex coupling only.

Ideally I'd like to change this with the diff in situ to save a load of hassle.

 

My concern is that the Haldex reservoir is part of the diff casing and will I be able to flush sufficient contaminated oil out by blowing fresh oil and conpressed air through fill and drain holes?

 

If not, can the diff casing be pulled off with the diff in situ or do I need to completely remove?

 

Thanks in advance for any advice

 

Andy

Hi,

I've read that the brake switch can throw off the haldex as the haldex disengages under braking so a faulty switch (foot or handbrake) can send the wrong signals and disengage haldex.

Second up is the earth lead from the haldex, that can rot apparently and cause the pump not to run.

It's easy to blame the unit itself.when often there can be other easier things to trace too.

Have you been to a vag specialist other than the indy or the vw franchised garage... it always annoys me when a "technician" uses a computer to diagnose a "fault" without considering the options.

I could be wrong , but I'd look at the cheap possibilities first before dropping 6k on  a diff . 😪

Thanks for the reply.

 

The pump is running so it isn't an electeical fault. The fact the fluid is contaminated and has metal particles in it proves the haldex unit has suffered mechanical faliure. Especially considering the fluid was changed and pump cleaned and it quickly became contaminated again.

 

The big question I have is around how advisable it is to change just the haldex coupling rather than a complete diff and haldex.

 

Also, if I change just the haldex coupling how do I ensure I clean all the swarf and contaminated oil out of the haldex fluid reservoir which is part of the diff casing.

Hoping for some first hand knowledge from someone that has done this.

 

Thanks

23 minutes ago, AJK87 said:

The big question I have is around how advisable it is to change just the haldex coupling rather than a complete diff and haldex.

My understanding is that the Haldex does not share fluid with the differential, so just because the Haldex fluid is contaminated does not necessarily mean there is any damage to the differential.

 

I would just repair/refurbish/replace the Haldex as a first step as it is very likely to fix the problem.

The Haldex and Diff have seperate oils that's for sure.

 

My understanding is that the diff casing is split into 2 sections internally. 1 acts as a diff oil reservoir and the other is the haldex oil rservoir. (This is the case on a gen 5 haldex)

 

This is a pain as simply replacing the haldex unit means swarf and contaminated oil will likely remain in the section of the diff casing that holds the haldex oil and this will cause the new haldex to fail prematurely.

 

I'm trying to find out from someone with experience whether with the haldex unit, and fill plug removed am I likely to manage flushing the reservoir out sufficiently, or will I need to split the diff casing.

 

Cheers

Have you actually seen with your own eyes this alleged swarf in the Haldex oil or on the filter guaze?

 

Even if it does exist I have zero confidence in a garage that concludes it is evidence of the clutch pack having failed, it would take millions of miles of wear (the clutch pack only wears when partially engaged and the vehicle making a turn) and the filter would have been clogged stopping the system from working literally hundreds of times before there could be any metal to metal contact.

 

Any swarf will almost certainly be from failure of the pump and the debris will have been contained witin the filter.

 

I would change the pump alone flushing through the oil reservoir before fitting then inspect the filter after 1000 miles.

 

The garage should have given this as a diagnosis if there is in fact metal swarf but then it would not have brought them a £6K payday.

Cheers for the reply JR

 

The first independent garage (which I worked at years ago when I was still in the trade) showed me the contaminated fluid and showed me the pump, the gauze was completely gunked up (on the outside of the gauze).

 

If the swarf was from the pump failing, surely it would be trapped on the inside of the gauze?.

 

Anyway, independent garage number 1 did an oil change and cleaned the pump gauze and confirmed that the pump was running. They believed the 4WD was fixed. It wasn't though, didn't work at all even when I first got it back.

 

Several months have gone buy as I've been struggling for time to sort it, decided to book it in at my local VAG dealer (VW)

 

They also confirmed that the pump is running but no drive to rear wheels. Removed the pump and oil which was all contaminated again and swarf visible. I was shown the photographs.

 

So it all suggests the route cause of the contamination and swarf is the haldex unit itself. The pump wouldn't leak that much swarf through the gauze into the oil and then again after an oil change surely.

 

Thanks for your thoughts, really appreciate any help or advise!

Hi,

I'd question if it was swarf or just rubbish from the friction pads that was getting flushed through with the new oil. If it was a mess to begin with then id expect the flushing from the new oil to cause that to become dirty too.

For it to gunk up again so quickly just with swarf there would need to be a lot of metal on metal contact so it want to see the mess from the filter and see what a magnet attracts.

I'd go with the plan J.R. has suggested. If the pump has worn then even if it shows signs of running then it might not be doing its job so that's one thing to consider, cheaper too than a whole new unit .

Hope you get it sorted.

The Haldex it’s comes with the controller under part number 0CQ 525 554 T and is £2552.53 retail inc. VAT. The debris that collects on the strainer can be present at as little as 20k miles, the one below was on a 20k Golf 7 R. What is odd is that I often see it in brand new genuine fluid to the extent we use a paint strainer to get it out, it looks like a plastic bag which has been in a blender or Gorilla snot as one of my techs called it.

 

 

 

If there has been that much crap in the Haldex surely the next port of call after the pump is the controller, surely that has small oil passages and solenoid operated valves that will probably be blocked up. (i assume this model of Haldex doesn't have an oil filter like previous generations did?

 

I get why a garage wants to fit a new one, because it will work after they have finished, you could spend hours of labor on this existing Haldex, it might work, it might not. If you don't want to get your hands dirty yourself then a new or recon unit is the way to go from a financial point of view

The garage doesn't want to fit a new haldex unit, they want to fit an entire new diff assembley, that's the haldex unit and diffetential combined. Cost of the parts alone is well in excess of £4k.

 

I'm not preoccupied with trying to fix the existing Haldex unit and don't intend to.

 

I'm more than happy to buy a reconditioned Haldex from ECU's direct for about £700 and fit it myself.

 

The question I really want answering which I keep eluding to is regarding flushing of old contaminated oil without removing the diff casing...

 

If I'm spending £700 on a reconditioned Haldex I don't want remnants of contaminated swarf filled oil circulating around it.

 

The Haldex oil reservoir is part of the diff casing, the casing has 2 sections internally. One for diff oil and one for Haldex oil. So removing and changing the haldex unit will not automatically get rid of all contaminated fluid.

 

What I'm wanting is knowledge from somebody with experience of working on this system in this guise with Haldex reservoir in diff casing.

 

Will I be able to flush contaminated oil out sufficiently with just Haldex and fill plug removed using compressed air and oil etc, or will I only be able to achieve this by splitting the diff casing and thoroughly cleaning.

 

That's all I want to know.

 

Hopefully somebody here has worked on this

I hope you find your answer but as you describe garages and dealers never split the two apart, i'm guessing there is probably a good reason for this and I think you probably know the reason. I've also never come across a DIYer on any sort of forum that has done this either so it will be interesting to see more of the goings on inside a Haldex and teh rear diff.

 

I vote you take one for the team and split the two for our interest 😁

Main dealers don't tend to split them, that's because under warranty VAG pay for a complete diff replacement, so they just adopt the same belt and braces approach on cash jobs.

 

It means they can more easily guarantee the repair with no comeback. In many cases it will be an over repair.

 

TPS and VW supply the whole diff assembley or the haldex unit seperately.

 

There's videos of the haldex and diff being stripped on Youtube. One by 'humblemechanic' and one by 'PT precision automotive' so it's perfectly feasible to do.

 

Ideally I want to replace the haldex with diff in situ and not have to remove the diff casing for cleaning. This makes it a drastically smaller undertaking and also means I don't have to lower the subframe which to date never has been. If I don't have to I'd prefer not to mess with all that and then have to do 4 wheel alignmnet after.

 

The question is whether I will manage flushing the vast majority of contaminated fluid out without splitting the diff and wiping out the haldex reservoir.

 

Looks like I will have to crack on with the work, make a judgement call on it and report back with some photos

Drain the Haldex oil and inspect it, then put a magnetic probe tool into the reservoir, if you do not find any significant metallic particles or swarf in either then you are worrying about nothing and the garage is taking you for a pigeon.

 

You can only do the best you can regarding flushing, anything that remains will not get through the gauze filter anyway.

 

Before changing the pump I would connect it to VCDS and look at the commanded and measured Haldex engagement figures, I may have invented the latter, if the pump is running, producing the correct pressure and the clutch pack engagement commanded at 100% but you have no drive to the rear wheels then there will be a problem with the hydraulic actuator.

 

Or someone has removed your propshaft!!!!

 Whatever you do, if you drain the diff oil, remember to fill it back up before the test drive 😂

 

(sorry couldn't resist)

On 16/10/2022 at 11:46, J.R. said:

Have you actually seen with your own eyes this alleged swarf in the Haldex oil or on the filter guaze?

 

Even if it does exist I have zero confidence in a garage that concludes it is evidence of the clutch pack having failed, it would take millions of miles of wear (the clutch pack only wears when partially engaged and the vehicle making a turn) and the filter would have been clogged stopping the system from working literally hundreds of times before there could be any metal to metal contact.

 

Any swarf will almost certainly be from failure of the pump and the debris will have been contained witin the filter.

 

I would change the pump alone flushing through the oil reservoir before fitting then inspect the filter after 1000 miles.

 

The garage should have given this as a diagnosis if there is in fact metal swarf but then it would not have brought them a £6K payday.

Wanted to follow up on this:

 

I drained all the fluid which was filthy, fired loads of brake cleaner into the haldex coupling reservoir and blew through with compressed air.

 

Fitted a new pump + oil and crucially carried out the reset haldex pump learned values procedure on a diag machine.

 

The issue has been fixed. I've now had 4wd working reliably for about 5000 miles.

 

I infromed the VAG dealer that I'd fixed it for approximately £6000 less than their diagnosis and insisted they refund my diagnostic charge

 

Thanks so much JR for your help!

 

Just need to fix my lack of power issue now

They'd probably argue that their 6k fix would have solved the issue too. 🤣.

Glad you got it sorted and saved yourself a load of cash !

15 minutes ago, 3rdoctavia said:

They'd probably argue that their 6k fix would have solved the issue too. 🤣.

Glad you got it sorted and saved yourself a load of cash !

The service manager responded with a politician like response in which he stood by his technicians diagnosis.

 

The implication being that they have to carry out repairs that last rather than try flushing things and risk a short lived repair.

 

That, on the face of it, makes sense. Reccomending a £6200 full diff replacement without trying a £200 pump first is a pretty wreckless way to behave in my opinion though.

 

I pointed out that had it been explained to me at the time of the diagnosis that there was a chance of fixing it with a pump, but with no gurantees of longevity, I'd have been able to make an informed decision.

 

Instead I had a quote for £6200 handed to me.

 

Despite the service manager's defensiveness, he did refund the diagnostic charge.

 

I've done 5000 miles now and am iminently going to do another haldex oil change!

 

Thanks to all that helped on here!

How much more did a 4wd variant of the Yeti or Octavia cost in the day?

 

I bet it was not £4K+

3 hours ago, AJK87 said:

 

I've done 5000 miles now and am iminently going to do another haldex oil change!

 

It will be interesting to see what the oil looks like this time round or of there is much gunk on the filter. 🤔

On 05/06/2023 at 17:37, 3rdoctavia said:

 

It will be interesting to see what the oil looks like this time round or of there is much gunk on the filter. 🤔

Well? We've all been holding our breaths!

6 minutes ago, ashghinn said:

Well? We've all been holding our breaths!

I've probably done 35k since the fix with a new pump and 4WD had never failed since. I've done a couple of fluid changes in that time, far more than is officially required but wanted to keep a close eye on oil and pump gauze.

 

The fluid has never been that dirty when I've changed it since the pump change and flush. The gauze has had a bit of sludge on it but nothing major. I'd say the sludge is just friction material rather than debris from a failed clutch pack.

 

So in summary the VAG dealer were talking B*****ks and had tried to grossly over repair my car.

 

Still going strong now just from pump and flush and fluid (and critically a pump reset learned values procesure on diag machine which is essential)

 

Thanks again to all that helped

I'm just embarking on a journey of discovery into the syrange world of Haldex.... were the average DIY owner knows so much more than the official dealers about all this! What a resourceful lot you all are! 

 

I recently bought a 4WD (well 2WD as I soon found out) Yeti with 100,000 miles on the clock and just ordered a new pump and oil from Haldexrepairs.co.uk. Hoping that'll be the  cure, but know I may have difficulties with the pump learning process.  Also may well discover issues with the controller kas these seem a common point of failure too. But who knows? Hearing stories of metallic bits in the gunk on the pump strainer, I splashed out on a magnetic sump plug too. Like AJK87, I expect to conduct pretty  regular oil changes to keep it all ship shape.

 

Wonder what produces the metalic debris reported in the filter by so many? Perhaps it is never the clutch, but simply the pump self destructing as a result of becoming overloaded by a blocked filter?

3 minutes ago, ashghinn said:

I'm just embarking on a journey of discovery into the syrange world of Haldex.... were the average DIY owner knows so much more than the official dealers about all this! What a resourceful lot you all are! 

 

I recently bought a 4WD (well 2WD as I soon found out) Yeti with 100,000 miles on the clock and just ordered a new pump and oil from Haldexrepairs.co.uk. Hoping that'll be the  cure, but know I may have difficulties with the pump learning process.  Also may well discover issues with the controller kas these seem a common point of failure too. But who knows? Hearing stories of metallic bits in the gunk on the pump strainer, I splashed out on a magnetic sump plug too. Like AJK87, I expect to conduct pretty  regular oil changes to keep it all ship shape.

 

Wonder what produces the metalic debris reported in the filter by so many? Perhaps it is never the clutch, but simply the pump self destructing as a result of becoming overloaded by a blocked filter?

I can't over emphasise the importance of the pump learn procedure.

 

Even if it is just the pump that is faulty, replacing it and not relearning the pump values might mean the right voltage isn't sent to the pump andnit still doesn't work, which could lead to in incorrect assumption that other hardware is at fault.

 

Mine was relearned successfully with some none VAG diagnostic software at an independant garage.

 

A decent independant shouldn't charge you too much to plug in and carry it out, it takes a few minutes.

 

OBDeleven has the pump learn function as I've seen it on mine, I can't vouch for whether it does tho job prolerly though as I've had no need for it since fixing mine.

 

Best of luck!

1 hour ago, ashghinn said:

Wonder what produces the metalic debris reported in the filter by so many?

 

Outright lies from main dealers on the make.

 

I made the classic "wrong hole" mistake when replacing the Haldex fluid, I ran the differential dry of oil for about 350 miles 200 of which an motorways and autoroutes, the tiny bit of oil remaining came out like charcoal as did the next 2 flushes of 50/50 oil and paraffin but there was no metal swarf.

 

Haldex filters get covered in schmoo but not swarf, there is nothing in the multi-plate clutch hydraulic system to create it, its just another lie trotted out by main dealers like "front and rear brake pads and discs 75% worn" who do not even have the intelligence to realise how implausible their lies are.