2012 A6 quattro 3.0Tdi EGR coolant leak advice

[aw911]

Evening

I'm hoping that someone may be able to advise in relation to where the EGR coolers leak from.

I have recently been using coolant and I think it is from the EGR cooler area judging by the liquid that I can see when I shine a torch in that appears to be pooling in the centre of the engine.

I have the 3.0 TDI (CDUC) V6 engine with the single turbocharger

Why do the EGR coolers leak? Is it an internal failure of the assembly or is it simply a case of seals/gaskets failing that could be replaced without the need to renew the EGR cooler complete?

I've been doing some searching on the Internet and lots of reference to EGR cooler leaks....but nobody goes into detail about why is actually leaking if that makes sense?

Any insight or information would be much appreciate before I strip out the intake manifold etc....to gain access.

Many thanks in advance.

[Yuri]

Hi. It might not be egr cooler its self,because there are a lot of o rings and rubber gaskets that can and do leak after time.
I saw video on youtube and guy runs garage and was doing this job. He showed which gaskets he replaced and part numbers too. It is in polish though.
Few links here
AUDI A6 4G 3.0TDI UBYTKI P�YNU CH�ODNICZEGO - YouTube (https://www.youtube.com/watch?v=TgPXp8dcddc&t=1102s)

AUDI A6 C7 3.0BiTDI Poważny Wyciek Płynu#MatPanewka# - YouTube (https://www.youtube.com/watch?v=4NqsAig9MJM)

[morski]

Ive had the same problem on my BiTdi and replaced all the o rings under the intake manifold. Whilst it was apart i managed to find a brand new genuine EGR cooler for £100 instead of the £760 audi want for it. The main culprit is the black plastic regulating valve. its a bit crappy and fails regularly. Not too bad at £66.

[aw911]

Hi....many thanks for the replies and links. I've been studying exploded parts diagrams of all the parts involved in the cooling circuit and I cannot for the life of me see why the EGR cooler itself as a complete assembly needs to be renewed unless the body corrodes through?
Completely agree about the regulating valve as that is a plastic assembly and I could definitely that failing and have see a thread on another forum where it had....but other than a number of seals the EGR cooler is an assembly that looks to be cast and has one seal/gasket that sits between the 2 halves of the body 059131599G....but other than that the rest is just o-rings.
Seems strange to spend nearly £600 on a complete new EGR cooler assembly 🤔 . Obviously I understand some people change them for issues with DPF and similar EGR related issues.....but I guess I just can't understand how a cast assembly can leak water other than through seals which are relatively cheap items comparative to the cost of a brand new assembly
There are various seals on the regulating valve and the intermediate flange assembly and there are also some seals on the oil cooler assembly that the cooling system ports through. So I think I will order all of those before I strip it down and a regulating valve assembly as they are about £50 and a known weak point. Then strip out the intake assembly etc....to gain access and see what is going on in that area.
Someone else told me to just chuck some KSeal in but I would rather fix the issue properly so I know what the cause was.

[Yuri]

Hi. I would not put KSeal simply because it will gunk up your cooling system and it really is only temporary solution to the problem,so best to get it done once and properly.

[Elansear]

Hi have not experienced this but it does seem to be a fairly common issue. Am I correct in thinking that the cooler is feed from the engine cooling system, if so could antifreeze be part of the problem. As it contains anti corrosion elements could it be that not replacing it every couple of years is causing seals etc to start to fail. As I say just a thought may be completely wrong but it would make sense when you think bout it. GLA

[aw911]

Thanks for posting up those videos.....its a shame about the language barrier as I would love to know what he is saying at certain points in the videos....but the content clearly shows what an issue it is given how much coolant is present in that area. I think that the EGR cooler only really needs replacing it the core is clogged and it is just the seals and the 2 plastic manifolds that are the likely failure points. Mine has just passed 100k miles on the odometer. Putting together a list of all the seals etc....that I might need and the necessary coolant etc....then will probably tackle it next month when I get some time.

[marciolo]

Hi
I should be able to translate that for you. Just pinpoint time frame of your interest.

[aw911]

That would be amazing.....the section is around 12 mins into the video where he is showing the parts that he has purchased. There is a bit where he is holding up what looks like the water pump shroud.....and I'm confused as to why that has come off and whether that needs to actually be renewed ....as it does not appear on the printed parts list or the bag labels that he shows in the video.
Many thanks in advance.

[marciolo]

Ok so video with BITDI engine Mat reckon that leak is from the part his holding in the hand at 9:43 min. into the video it's leaking from the shaft that runs a cross of that tube[in the middle]. The section you ask about 12 min. into the video his talking about how flat is the gasket and he is going to replace both of them. Video with 3.0TDI Mat suspects the leak from the o_ring his holding in 10:00 min. into the video.
I hope it's all clear to you.

[aw911]

Thanks for the translation.....it looks like the regulating valve is a common failure point on these from other YouTube videos and vids that were posted up on this thread. I've ordered all the seals and gaskets plus the manifold assembly and the regulating valve assembly.....total came to £89 so hopefully will get chance to strip down and rebuild it over the next few weeks. Many thanks for all the replies and for the translation. Much appreciated.

[aw911]

Ok....so moving on from this i was forced into action sooner than I intended as the serpentine belt snapped on the engine. So I made space in the garage and commenced work.

Removed the front bumper, headlights and the radiator and intercooler to allow maximum space and to get into the engine better....plus I was changing the belt and idler pulleys too.

Stripping out the top of the engine was a fun job....there are so many electrical connectors and looms.....even getting the intake manifold is not that simple. EGR cooler was clogged up so I cleaned the tubes out. The throttle body by the EGR was covered in carbon and crap from the poxy EGR so cleaned those all up too.

Found the leak issue was caused by the actuator assembly mentioned previously...the plastic body had split at the actuator pivot so the coolant was leaking out there. Took out the oil cooler and cleaned the V out of oil and coolant etc......put it all back together with new seals etc and a new actuator assembly.

Replaced the water pump while I was there doing the serpentine belt. Have put it all back together and changed the oil filter and oil (took more than usual due to removing the oil cooler etc) which was about 7.2 litres of oil compared to previous oil changes where its more like 6.5 litres. Recharged the coolant system using a vacuum charging kit which made it a doddle. Have bled the last of the air out of the system via the EGR cooler bleed point and the heater matrix bleed point by the windscreen. Took approx 10 litres of coolant.

Cleared any faults with VCDS and then took it for a test drive. All seems OK. Heating gets toasty warm.....although I may revisit it as the drivers side is blowing colder air than passenger side. Dont appear to be any leaks but will keep an eye over the next week or so.

But here is the weirdest thing......the passenger side knee airbag short to ground fault has gone? No idea why.....maybe where it has been inside a dry garage for the past 10 days while I've been working on it intermittently?

Anyway all up and running and happy to have her back on the road. Thanks for the videos that were posted up and the translation services....they were invaluable.

[marciolo]

Happy to hear that you manage to fix your car. Did you had any colant leek on the serpentine belt ? What's the milage ?

[aw911]

There was no coolant leak on the serpentine belt....I think that was just one of those things that failed and happened to be at the same time. The car has covered 105,000 miles.
To be honest taking all the radiators etc off gave me much better access to the engine for changing the areas where it was all leaking anyway.

[Rpw866]

Hi, looking at doing the same job, I've bought all the parts but I'm having second thoughts and thinking of getting a garage to do it after seeing more videos it looks a total bitch!! Is it that bad it looks worse than it is? Thanks

[aw911]

I guess it depends on how practical you are? My hand was forced as the serpentine belt snapped so it made me tackle the job in the winter...but luckily I have a garage that I managed to squeeze the car into.

I think the job took me 2 days in total....I also replaced the water pump and a few pulley bearings as well while I had the front of the car stripped down due to renewing the serpentine belt and removing the remains of the old belt.

Take pics while you're stripping it down....you'll appreciate them when you come to put it back together. Also maybe get a paint pen and make marks on pipes, electrical connectors to help you identify where they connected.

The job isn't too difficult. You will need to drain the coolant system down and I would probably suggest doing an oil change after this job as well. I certainly wouldn't want to do it on the driveway in the winter.

The part that leaks is unfortunately right in the centre of the engine so you need to remove loads of stuff to gain access. Lots of seals/gaskets to renew. I imagine it would probably be a quite costly job if you took it into a garage as it is quite time consuming.

[aw911]

So roll onto 2023 and once again my coolant is needing to be topped up and I can see coolant accumulating in the centre area of the engine block. It appears that the regulating block has failed again....as per the previous failure mode

Checking parts catalogue I can see the regulating valve has been superseded......previously it had a suffix of H but is now on revision M. Calling my local Audi to check parts they have 100s of these in stock....so that suggests that there is a problem with their design and that they fail quite frequently.

It's lasted approx 40k miles since I changed it last time! Already dreading stripping all the stuff out for access etc.....

Its yet another piece of kit which is designed to help reduce emissions but just overcomplicates things and makes more things to go wrong.

[Harvy23]

Thanks for all the information and updates in this thread. I have a mystery coolant leak on my BiTDi. I haven’t shone a torch right down into the valley yet but I did see a couple of drips near the front of the block and the serpentine belt looked like it was wet. I’m losing a litre or so over about 300 miles. I have a feeling it’s going to be the gaskets round the Egr cooler or the actuator. Do you have a complete list of parts you ordered, or did you just order what was in the video from Mat? How did your secondary fix go earlier this year? Was it the same issue again? I fear I have a few long nights ahead of me…

Edit for spelling.

[bluezie]

I've just done mine, CDUD engine. The coolant valve is now 059 121 737 AM, so it's been revised again.
Yes, it's a very fiddly job, so many things in the way of hard to get to bolts. It's a job that if rushed will go very wrong, particularly, as any bolts and tools dropped are gone for good, so strip it all down again to retrieve.
Notes-
An aquavac is a must, as I had a lot of coolant and oil escape when taking the oil cooler off.
The O/S fuel rail feed pipe will need to be disconnected from the rail, and moved slightly to access one manifold bolt.
The manifold needs to be pre-loaded with at least one bolt, as one is impossible to fit once the manifold is in position.
Allow time to clean soot from the manifold, EGR pipe, and butterfly valve. I used Mr Muscle oven cleaner, and it's a VERY messy job! Although after 100,000 miles it wasn't too bad.
Replace ALL seals and coolant components.
The fuel pressure sensor is in the way of the manifold removal. If you remove it, it has to be replaced or it will leak £138.00. Spend a few minutes more unbolting the rail to move the sensor out of the way.

[Taj147]

Thanks for the translation.....it looks like the regulating valve is a common failure point on these from other YouTube videos and vids that were posted up on this thread. I've ordered all the seals and gaskets plus the manifold assembly and the regulating valve assembly.....total came to £89 so hopefully will get chance to strip down and rebuild it over the next few weeks. Many thanks for all the replies and for the translation. Much appreciated.

Hi mate do you have links or part numbers for all the parts that you bought? I've got the same issue but been quoted £950 in total after already paying 50 for a diagnosis..

[Alexutz Preda]

Ok....so moving on from this i was forced into action sooner than I intended as the serpentine belt snapped on the engine. So I made space in the garage and commenced work.

Removed the front bumper, headlights and the radiator and intercooler to allow maximum space and to get into the engine better....plus I was changing the belt and idler pulleys too.

Stripping out the top of the engine was a fun job....there are so many electrical connectors and looms.....even getting the intake manifold is not that simple. EGR cooler was clogged up so I cleaned the tubes out. The throttle body by the EGR was covered in carbon and crap from the poxy EGR so cleaned those all up too.

Found the leak issue was caused by the actuator assembly mentioned previously...the plastic body had split at the actuator pivot so the coolant was leaking out there. Took out the oil cooler and cleaned the V out of oil and coolant etc......put it all back together with new seals etc and a new actuator assembly.

Replaced the water pump while I was there doing the serpentine belt. Have put it all back together and changed the oil filter and oil (took more than usual due to removing the oil cooler etc) which was about 7.2 litres of oil compared to previous oil changes where its more like 6.5 litres. Recharged the coolant system using a vacuum charging kit which made it a doddle. Have bled the last of the air out of the system via the EGR cooler bleed point and the heater matrix bleed point by the windscreen. Took approx 10 litres of coolant.

Cleared any faults with VCDS and then took it for a test drive. All seems OK. Heating gets toasty warm.....although I may revisit it as the drivers side is blowing colder air than passenger side. Dont appear to be any leaks but will keep an eye over the next week or so.

But here is the weirdest thing......the passenger side knee airbag short to ground fault has gone? No idea why.....maybe where it has been inside a dry garage for the past 10 days while I've been working on it intermittently?

Anyway all up and running and happy to have her back on the road. Thanks for the videos that were posted up and the translation services....they were invaluable.

Hi, I know it’s been a while, but has anyone got the part numbers I need to replace all gaskets and everything else relating to this issue? I have a 3.0tdi cdt engine that has the exact same kind of coolant leak.

Thanks !!!