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  1. #1
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    Replacing crankcase breather on 2.5 V6 TDI - photos and description

    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.

    Hope those photos are useful for anybody else contemplating the job. I'm glad I did it, but it was fiddly.
    2010 A6 Avant TDI S-Line LeMans
    1999 A6 Avant 2.5 TDI Quattro - gone, not forgotten.

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  3. #2
    Turkster's Avatar
    Bro.Paul 2.5TDI Quattro Sport

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    a great write up, it is a job i have done, and wont be too pleased to do again, i did not have the flexible extension bit of kit that you had for the EGR valve removal, i will be investing in one, where did you get it from ?

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    I've had that flexible extension for years so I can't remember where I got it. It's part of a cheap-and-cheerful ratchet screwdriver kit that sometimes comes in handy. I can't apply much torque with it but it's useful when I need to do lots of turns to undo a long thread.

    Thanks for the comment. Maybe the write-up will be useful for someone one day.
    2010 A6 Avant TDI S-Line LeMans
    1999 A6 Avant 2.5 TDI Quattro - gone, not forgotten.

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    wow, i think the soot build up is far more significant than i had ever imagined.
    Does then make you wonder what sort of state the turbo is in, for that mnatter the exhaust...

    .. no idea but is it possible to low out the soot on the engine cycle? ie with addatives or such or do these have minimal effects.

    However all that cleaning has to make the car run better without a shadow of a doubt. And nice write up and well documented, even the haynes manual hand in the way, wonderful...

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    Thanks istoo.

    I didn't find a chemical that dissolved the build-up of oily soot easily. Brake cleaner did a bit and so did Jizer degreaser, but neither was perfect.

    The aluminium duct across the front of the engine is fed from a rubber tube a couple of inches in diameter, and I peered down into this to see whether the build-up went all the way through the intake. From what I could see it was mainly just the aluminium sections right before the heads that were clogged. The rubber tube was fairly clear. I don't know whether there's an intercooler (I imagine there must be) but one day perhaps I'll investigate further.

    Maybe the car's running better now; it's hard to tell. If I had to guess I'd say it is. But then I always think the car is faster/quieter/smoother after I wax it, so I'm not the best judge of performance
    2010 A6 Avant TDI S-Line LeMans
    1999 A6 Avant 2.5 TDI Quattro - gone, not forgotten.

  7. #6
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    Quote Originally Posted by SiliconS View Post
    But then I always think the car is faster/quieter/smoother after I wax it...
    i am with you there, brilliant!

  8. #7
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    Thanks for that brilliant write up, I was building up courage to do mine, and this was just in time
    If you can't beat them, arrange to have them beaten

    2000 B5 2.5tdi V6 (if only it were a quattro)

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    Q:
    I took the intake manifold piece of at the front after seeing how clogged yours was. It was quite clean. Got some photos from the digicam to download for some comparison. However towards the passenger side og the manifold the inside was distinctly oily, is this right? Shouldn't it be sooty in that section? should it be dry?

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    The intake could be drawing in oil mist from the crankcase breather that accumulates in the manifold ducting. The aluminium castings were clogged with mainly dry carbon on my car, but the flexible rubber hose just before the aluminium tubes was oily.

    It doesn't sound as though yours is that different to mine, but I don't know whether it's "right" or not :D
    2010 A6 Avant TDI S-Line LeMans
    1999 A6 Avant 2.5 TDI Quattro - gone, not forgotten.

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    thanks for the great write up, it will be a big help when i fit the breather later on today

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    How did you get on with the job, white.akita?
    2010 A6 Avant TDI S-Line LeMans
    1999 A6 Avant 2.5 TDI Quattro - gone, not forgotten.

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    i managed to get it done yesterday, it took me over 3 hours in total.
    i had a right mess on with the egr pipe as it seemed to cover alot more of the opening on my car than the pics showed on your car.
    i massaged it into place with a hammer ! but then had trouble lining the two flanges back up with the tapped hole on the manifold !
    i should have tried to of taken the two egr pipes off completely, but its done now thank god.
    everything else went like clockwork and i wouldn't of even attempted it without your excellent write up so thanks again

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    2010 A6 Avant TDI S-Line LeMans
    1999 A6 Avant 2.5 TDI Quattro - gone, not forgotten.

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    mine is distinctly oily!

    breathers i didnt get to, was getting too nervous about dropping a bolt by that point...

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    Quote Originally Posted by istoo View Post
    mine is distinctly oily!

    Oil is OK, I think. It helps the engine breathe better by lubricating the pipes to let the air through.
    2010 A6 Avant TDI S-Line LeMans
    1999 A6 Avant 2.5 TDI Quattro - gone, not forgotten.

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    i will go with that theory makes sense to me.
    still, worth having a probe, thanks for the informative post

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    silicons excellent write up!, just bought new breather to fit this weekend but already got nasty oil leak (i think my engine breathes through several blown seals) did fitting help with your leak, or was it too late

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    Thanks olds_kool

    Changing the breather has *helped* with the leaks but they haven't gone altogether. There's still a 10p-sized spot of oil on the ground after the car stands for an hour when hot.
    2010 A6 Avant TDI S-Line LeMans
    1999 A6 Avant 2.5 TDI Quattro - gone, not forgotten.

  20. #19
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    Crankcase breather

    A very big thanks for posting this article. Changed the breather myself last week-a job i would not have considered until i saw your post. Probably saved me a good few quid in the process. Now all i have to do is find a bloody annoying oil leak!! Thanks again

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    Quote Originally Posted by Whymelord? View Post
    A very big thanks for posting this article. Changed the breather myself last week-a job i would not have considered until i saw your post. Probably saved me a good few quid in the process. Now all i have to do is find a bloody annoying oil leak!! Thanks again
    Glad it helped someone else - that's why I posted it.

    The oil leak on my engine died away after I replaced the breather. Give yours a few weeks and it might do the same. A blocked breather causes crankcase pressure build-up and that pushes oil out of the weakest seal.
    2010 A6 Avant TDI S-Line LeMans
    1999 A6 Avant 2.5 TDI Quattro - gone, not forgotten.

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    Thanks SiliconS

    Just the 'Dogs bolloc*s! -Good work.
    Got me the same problem on 2.5tdi
    Changed the breather 'filter - no joy
    still leaked- Thinking of having a go
    at cranckcase pressure regulating
    valve ( part of the oil filter housing
    behind the breather filter housing)
    Cannot get any information on how
    this gizzmo works but guess its
    like a PVC valve stopping inlet
    manifold vacume sucking the
    crank case dry .
    Having peered into the 'guts' it
    would seem the injection pump
    has to come out! (deep breath)
    Guess its just yet another example
    of vv.poor design by Audi.

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    When i did the breather filter change i removed the section between the turbo and the exhaust. This helped create space to undo the pipe from near the turbo to the egr valve. It was fairly easy from there on. Bl**dy Audi sold me a new part but its exactly the same as the OE not the new part that SiliconS fitted.

    Where did you get that from SiliconS and how much? cheers.

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    I just had a go at this, refitted everything and then realised I forgot to put the crankcase breather cover in. I am so frustrated, all those injector pipes have to come out again, argh!

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    Quote Originally Posted by Joni_s View Post
    Bl**dy Audi sold me a new part but its exactly the same as the OE not the new part that SiliconS fitted.

    Where did you get that from SiliconS and how much? cheers.
    Quote Originally Posted by SiliconS
    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".
    I got it from an Audi dealer but I had to order it. I can't remember how much it cost. I think about 30 or so.
    2010 A6 Avant TDI S-Line LeMans
    1999 A6 Avant 2.5 TDI Quattro - gone, not forgotten.

  26. #25
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    SiliconS - Aha! oops missed the bit about the part number. Many thanks for this.

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    No worries.
    2010 A6 Avant TDI S-Line LeMans
    1999 A6 Avant 2.5 TDI Quattro - gone, not forgotten.

  28. #27
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    I did mine today myself and had a bit of a shock when I uncovered the breather!

    Worked out near enough the same as posted above but I had to remove the EGR completely to get the breather cover off. It was awkward but I managed to get the flange off where it joins underneath the turbo (two 12mm nuts).

    Anyway, got it all stripped and it had already been replaced with the new type breather! I changed it anyway for the one I bought but it was a whole load of work for nothing. Ah well.

    Intake manifolds were in bad shape also, probably a bit worse that the pictures above but I soaked them in WD40 first which didn't do much good, so I ended up soaking them in petrol which did the trick and then dried them out with an airline.

    Anyway, one piece of advice. Already advised by SiliconS, I will second the motion to get the magnetic pick-up tool. I bought one specifically for this job and I wouldn't have had a hope of doing it without it.

    Definitely running better now. Thanks a million for that original post.

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    Its definitely not as easy as it looks, i too had to remove the EGR completely to gain access on the breather. Got myself an aftermarket and so far its doing good.

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    Quote Originally Posted by archebald23 View Post
    Its definitely not as easy as it looks, i too had to remove the EGR completely to gain access on the breather. Got myself an aftermarket and so far its doing good.
    has anyone tried mr gasket crankcase vent valve? this is much cheaper than the one i bought but ive heard good reviews about it.

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    I did mine yesterday. What a nightmare job, wouldn't have been able to do it without all the tips and advise here. I'd gently massaged the egr pipe from the turbo over just enough to pull the filter out. Cleaned and changed everything. My OCD monkey was going bananas, cut off the fingers off rubber gloves and covered all injector lines, injectors, etc.

    As recommended I'd cleaned all the ally pipes and the manifolds. Yuck, what a filthy job. I'm dying to take it out for a drive.

    Mine's an AKE. One thing I'd like to add, watch out for the 2No copper seals when taking off the turbo oil feed banjo bolt. The thread on the bolt should hold 1 of them, the other sits below the oil feed pipe.

    Now we'll have to see if the oil leaks dry up. I'm hopeful, but nothing is guranteed. Thanks everyone.

  32. #31
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    No need to do that on the late post 2000 engines as they've fitted the new, redesigned part !
    FOR SALE:
    -Golf mk 5/audi a3 1.6 FSI fuel pump, brand new genuine part boxed + seals
    -audi a3 (1998 to 2003) genuine clutch slave cylinder to fit 1.6 engines BRAND NEW
    -Rear bush press tool to fit new rear axle bushes on Golf Mk3/4, Audi a3/S3, Seat Leon/Toledo, Skoda Octavia mk 1/2 used once

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    Hello Chris! Oops. I'd forgotten to mention that the redesigned part had already been fitted. The guys at Audi said it was the crankcase vent filter when they took my oil filter cap off with the engine running. There was lots of thick oily smoke. I'm fedup with leaving engine oil wherever i park my car. Hope to fix it soon.

  34. #33
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    That's normal blowby and its an indication of the engine health- it might need a rebuild in the future... Unless there is hissing sound from crankase when removing the oil cap then it's no need to replace the engine breather...
    FOR SALE:
    -Golf mk 5/audi a3 1.6 FSI fuel pump, brand new genuine part boxed + seals
    -audi a3 (1998 to 2003) genuine clutch slave cylinder to fit 1.6 engines BRAND NEW
    -Rear bush press tool to fit new rear axle bushes on Golf Mk3/4, Audi a3/S3, Seat Leon/Toledo, Skoda Octavia mk 1/2 used once

  35. #34
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    excellent "how to" SiliconS.......if i ever have to replace mine.....this thread is in my bookmarks......muchas gracias.

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    Thanks for taking the time to reply, scrag. I hope my description will be useful for you.
    2010 A6 Avant TDI S-Line LeMans
    1999 A6 Avant 2.5 TDI Quattro - gone, not forgotten.

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    Great post mate, looking at doing this myself, but having trouble finding the gasket kit for the air intake that was coated, so will be worth taking it off for a look, mine is the 2.5 V6 BDG engine code, but any idea on where to get the gaskets from?

  38. #37
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    Quote Originally Posted by outspokenjimbo View Post
    any idea on where to get the gaskets from?
    I'm afraid I didn't replace the gaskets so I didn't try to source new ones. Good luck with your search though.
    2010 A6 Avant TDI S-Line LeMans
    1999 A6 Avant 2.5 TDI Quattro - gone, not forgotten.

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    Hi, I had a go at this and the filter would not come out. The pipe exhaust from the turbo was really covering the filter top on my car engine is ABF. I tried very hard and think I have bent the pipe under the turbo a bit with a screw driver hopefully it will still run OK.

    Ended up trying to wipe of some of the stuff off the filter with my fingers in the filter housing.

    I also can not locate the ERG valve back in where it bolts.

    Probably going to have to try again, Sam1909 said to take off the turbo pipe.

    Will try this when I get another chance.

    Just got to go back out an blead the fuel lines lets hope it starts.... What fun...

 

 

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