Replacing crankcase breather on 2.5 V6 TDI - photos and description

[SiliconS]

I posted this in *cough* another Audi forum (can I say that here?) last April. I've just signed up here too and thought it might be useful to some of the people reading the forum.
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Thought I'd write up the steps I took last weekend to replace the crankcase breather filter on my 1999 A6's V6 2.5 TDI engine.

The car has had an oil leak for months now and I've replaced the cam cover gasket to try and cure it. At the last service the mechanic told me it's now the offside camshaft front seal that's leaking but I'm not paying £££ to replace it. It can carry on leaking for the money it'd cost to sort out. Recently I've noticed that there's a hiss from the oil filler cap when I remove it, which indicates that the crank case is under pressure and that the filter could be blocked. That might explain why oil is coming out of the engine. On the advice of several forum posters, I didn't buy the replacement filter for my AFB-code engine; I bought the later-model type. Photos below show the difference. The part number for the one I used is 059103464B and it's described as a "set of seals". None of the three dealerships I called had it in stock.

In summary, this wasn't a particularly hard job but it was fiddly and there's a huge risk of dropping tools, bolts etc. into the V of the engine and losing them forever. I only lost one tool (a 5mm allen bit) which was better than I was expecting. I couldn't have done the job without a magnetic pick-up tool to hold things in place while I positioned tools and bolts, particularly during reassembly.

To do the job you'll be disturbing some fairly important components (fuel pipes, turbo oil feed pipes) and working with limited access, which might be daunting. Having the opportunity to clean out the intake manifolds while you're there is good though, and it makes the job worth doing yourself IMHO.

Having removed the cover from the engine it looked like this:





You'll need a 10mm socket to get the engine cover off. The filter was hidden in the V of the engine between the turbo and the fuel pump, under a metal cover plate:



First step was to remove the fuel pipes between the fuel pump and the injectors. I marked the fittings at the pump with a permanent marker in the order I removed them. You can't get a spanner onto the bottom ones with the top ones in place so you'll have to re-fit them in the correct order. Spanner size is 17mm.





Having removed all the pipes I next took the turbocharger heat shield off. There are just three 10mm bolts easily accessible on the top of the shield. For good measure I also removed the bolt holding the EGR valve to the nearside intake manifold. This is a 6mm allen key but access is fiddly and I used a flexible extension drive to get to it.



The pipes attaching to the EGR valve are stiff though, and removing that bolt didn't give me much extra room to manoeuver.

Next, I removed the large vacuum pipe from the top of the crankcase breather by squeezing the tabs of the clip together with some adjustable pliers. The rubber hose slid off fairly easily.



With the hose out of the way I was able to access the two 30H torx bolts holding the filter cover down and remove it. The filter was now loose and quick wiggle showed that it still wasn't going to come out of the space between the fuel pump and the turbo. Bloody thing. So I removed the two 5mm allen bolts holding the EGR pipe to the intake manifold, hoping this would give me more flexibility in the EGR's pipes:



Finally, the filter came out.



The recess in which the filter sits has only small holes at the bottom, so there's minimal chance of losing something into the bowels of the engine. There's an O-ring sitting in a groove around the filter recess and a new one in the replacement kit so don't forget to use it.

The new filter and the old one are very different but fit within the same recess. The new one is larger and there was no way it was going to fit past the other components and reach its hole without me creating more space somehow.



I disconnected the electrical feed to the fuel pump first. Next, there's a hard oil pipe feeding the turbo that cuts the corner of the space above the filter recess, so I decided to move it. More combinations of extensions down to a 5mm allen bit did the job, but you'll be wise to have a magnetic pick-up tool handy to bring out the long bolt once it's loose.





I could now use a screwdriver blade to bring the end fitting of the oil pipe out of the aluminium casting into which it fits. The fitting pushes in with an O-ring to seal it as the pic below might illustrate:



The pipe was still fairly rigid though - I had to remove the oil feed fitting from the turbo (9mm allen head) and the bracket from the rear of the offside intake manifold (13mm spanner) in order to move the pipe enough to get decent access.



The new filter dropped in relatively easily now so I installed the O-ring then the filter, cover and Torx-head bolts (which all came in the kit).

Job done. I could have stopped there and reassembled everything but a couple of comments in the forums made me decide to investigate the condition of the intake manifold sections. With everything exposed it was easy to take them off for inspection. I'm glad I did.



There was significant build-up of oily carbon deposit inside the pipes:







:***: This is on a 125k mile '99 A6.

I cleaned out the sections and refitted them. Cleaning was easiest with mechanical intervention. Chemicals didn't really seem too effective and sandblasting only reached the bits that were visible. I soaked the parts in Jizer first and then used a stiff bottlebrush and a wire rod to get the worst of it off. I used the Hoover to collect the bits from the intake runners on the heads as I scraped off the build-up. I hope it was worth the effort...

Having reinstalled everything I had to bleed the injector pipes before the engine would start. I got my wife to crank the engine while I loosened an injector pipes at the cylinder head until fuel spurted out. I tightened the fitting again and moved to the next pipe. After three pipes the engine was trying to start and after four it was running, but I did all six for good measure.

Has it fixed the oil leak? Not sure yet. The oil that's dripping off the car now might just be left over and will gradually stop. We'll see. [Edit: Yes, eventually the leak virtually stopped]

Hope those photos are useful for anybody else contemplating the job. I'm glad I did it, but it was fiddly.

[Shaka1976]

Getting a sense of De ja vu reading this thread as I only did this a few weeks ago. Though I didn't go are far as cleaning out the intake manifold. I did take the opportunity to take off the EGR and gave it a good clean though. Unfortunately it didn't cure my oil leaks......

[mhobson]

Hello, I am doing this at the moment for the second time, this time I am fitting the modified filter, the last one was only fitted new in 2008 and has blocked already. I wonder if you have any clever ideas as to how to loosen the vertical bolt close to the inlet manifold connecting the egr valve, if not possible it means removing the complete turbo unit, picture attached, Regards, Michael

[SiliconS]

Sorry Michael. The EGR was a pain in the *** and I didn't manage to get it out the way. So I can't help with that bolt, but if it's any help I managed to change the filter without removing the EGR.

[mhobson]

Hello, Yes I have changed the filter before without removing the EGR but I have seen so much written about EGR problems I thought I would remove it and give it a clean, but as it is so difficult to remove and looking into it with the feed pipe removed it seems reasonably clean and seems to be seating OK I think I will leave it again for another day, but looking at the state of your inlet manifolds, I would not be surprised if your EGR was in fact quite clogged. Regards, Michael

[ßÛŠΤΞЯ]

Great write up thanks

[A6Glider]

Just been told i need new filter

Problem is its at least the 3rd replacement in 30k miles

The first one lasted at least 70k until just after a belt change

Any idea of the reason why it needs changing again.

[mhobson]

Just been told i need new filter

Problem is its at least the 3rd replacement in 30k miles

The first one lasted at least 70k until just after a belt change

Any idea of the reason why it needs changing again.

Hello, Make sure they fit the new type filter as shown in the pictures of this excellent post. They will try to sell you the old one with the fabric filter because that is the one listed for your engine but insist, as I had to do, against the garage's advice, and get the new type filter without the fabric element. It is this fabric element which gets blocked. Regards, Michael

[A6Glider]

Thanks Michael

Any idea how many miles the new one will last


and what causes this to clog in the first instance. As I seem to have been through 3 outside warrently and severy inside warrenty and I am a low mileage user.

Begs the question why Audi have not officially issued a change notice

[mhobson]

Hello again,

Firstly I have had one of the original filters block at only 8000 miles.

It was explained to me by a very experienced diesel engineer that the problem is with the design of the original filter. The filter separates oil mist from the recycled crankcase gases and returns it to the sump before the gases are burned through the engine, which makes the engine run cleaner and at the same time reduce oil consumption. The filter is not there to remove sludge or suchlike and it is not blocked by such. What seems to happen is that the individual filaments of the fabric element absorb oil and as they do so they swell, reducing the space between each individual filament eventually blocking the flow. What is surprising to me is that even though VAG have obviously realised the problem and developed a new filter without this inherent problem (it maybe works on more of a centrifuge principal, but don't quote me, but the new filter does work very well) VAG parts lists still identify the old problematic filter as the correct filter for your and my cars and it still gets fitted I have no idea why it is still being made and sold, but I suppose the garages won't complain of the extra work. I nearly had a fit the first time I was embarrasingly engulfed in a cloud of smoke at a traffic lights and found out that it was coming from my well loved and cared for quality german car. So the advice is do not ever fit the original design filter but only fit the filter reccommended for the later V6 tdi engines. The new part is : V059 103 464 B, the old part was : V059 103 464, Regards, Michael