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Diesel leak 2.5tdi and bleeding

mixmaster Oct 3, 2011

  1. mixmaster

    mixmaster Member

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    Looks like I have to replace the 2 metal feed/return pipes running under the drivers side sill.

    They run between 2 splitters so as far as I can see replacing them is pretty straightforward.

    However, I am a little worried about the possibility of having to bleed the system after as I assume I will have to drain off any diesel left each end when I undo the pipes...

    Has anyone had experience with this?

    Thank you.

    (Oh, and Audi wanted just shy of £200 for a fuel line 'kit' so any pointers in the right direction for lines would be much appreciated!)
     
  2. adamss24

    adamss24 Well-Known Member

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    Do you have visible leaks ?
     
  3. mixmaster

    mixmaster Member

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    Yeah I noticed marks on the drive. Cleaning the area and removing the clamp showed corroded lines which obviously leak when running the engine.

    Picture Here
     
  4. aragorn

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    Pic doesnt work!
     
  5. PAULF

    PAULF Active Member VCDS Map User

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    I had similar happen to me - I caught it on rocks in my drive.
    I cut out the bad bit and fitted a rubber diesel pipe into that section. I didn't drain anything, just did it fast! You can only do this with short sections near the back though, as the return pipes work as coolers for the fuel. Audi suggest that the temps can get to very hot degrees!
    As for bleeding it, if it is just the twin returns, you won't have to. If it's the feed, fill it with fuel from the front by the filter before you try and start the car and you should be fine.

    (BTW I couldn't access your pic)
     
  6. mixmaster

    mixmaster Member

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    Really? I'm using Picasa (just made the album Public).

    Off topic I know but not sure how it works. Picasa gives me a picture link as follows:

    https://picasaweb.google.com/lh/photo/bN5MJVB1CgTgKTmhWCtFZX4Lmzx3RBmK5STeUCcQXvs?feat=directlink

    and a 'Embed Image' code:

    <table style="width:auto;"><tr><td><a href="https://picasaweb.google.com/lh/photo/bN5MJVB1CgTgKTmhWCtFZX4Lmzx3RBmK5STeUCcQXvs?feat=embedwebsite"><img src="https://lh5.googleusercontent.com/-R747oY5zYL0/TorEGLc23MI/AAAAAAAABCQ/SU2789qM2Dc/s144/P9290668.JPG" height="108" width="144" /></a></td></tr><tr><td style="font-family:arial,sans-serif; font-size:11px; text-align:right">From <a href="https://picasaweb.google.com/fluidlines/Audi?authuser=0&authkey=Gv1sRgCMaJtZXI5aj7Ew&feat=embedwebsite">Audi</a></td></tr></table>

    Any suggestions and I will get the pictures up! Thanks.
     
  7. mixmaster

    mixmaster Member

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    Thanks PAULF. I assume the 'twin returns' are the steel pipes - any reason why they go from single to twin and back?

    The salt must have got to them. The rubber feed seems fine.

    Would you know if the tank is likely to drain when opening the return pipes? I guess I will have time to take them off have a set made up and refit them.
     
  8. PAULF

    PAULF Active Member VCDS Map User

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    I'm fairly sure it's for increased cooling capabilities - which is why you need to be careful if replacing parts with rubber. Remember the pressures the pump works under, so any fuel can get very hot in the wrong circumstances.

    As for draining the tank, I blocked mine off whilst changing them, so I don't really know, but you could always put rubber pipes on with the ends blocked with a bolt whilst you make up some more
     
  9. aragorn

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    in my experience the return lines go in the top of the tank, and deposit fuel inside the swirl pot. I wouldnt think you'll empty the tank from disconnecting it, just the line.
     
  10. mixmaster

    mixmaster Member

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    Just about to strip them so will let you know how I get on.

    What do you think of replacing them with copper as a cheaper alternative to having steel fabricated?
     
  11. PAULF

    PAULF Active Member VCDS Map User

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    Probably do the job well -

    except for dealing with the dissimilar metal corrosion that you'll get on the steel parts at each end....
     
  12. mixmaster

    mixmaster Member

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    True.
     
  13. PAULF

    PAULF Active Member VCDS Map User

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    How did you get on with your fix?

    I've just taken my lines out again, this time with ice lumps on my road, so will be looking to do a more substantial repair myself.

    I was thinking of your copper pipe solution, and join them to the steel with a short length of rubber diesel pipe to negate the electrolysis.
     
  14. mixmaster

    mixmaster Member

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    It was pretty easy in the end. Only issue was working in a confined space and getting the old return pipes off.

    I soaked them in Plus Gas then used a 19mm to hold the splitter whilst I wound off the pipes with the 13mm. Difficult thing is to not upset anything you can't see tank side and engine side of the splitters.

    Then I had a fabricator make up two lengths of pipe with the old 13mm 'nuts'; I can't remember the name of the material but it had the strength of steel and the pliability of copper so I could bend it to shape with my hands as I went. Pure copper doesn't like diesel I think.

    Job done £30 later, but need to tweak the nuts as I have noticed a dampness...

    Let me know how you get on.

    BTW have you tried the 2-stroke idea? I have just started using it in mine.
     
  15. boya

    boya Member

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    How are you finding it mate??
     
  16. mixmaster

    mixmaster Member

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    Hard to tell straight away. I added 300ml to a full tank as advised.

    Possibly quieter quicker on cold start up (-10) but for me it's all about lubricating and preserving that increasingly delicate (195k) fuel pump.

    Will report back on how I get on.
     
  17. aragorn

    aragorn "Stick a V8 in it!" Staff Member Moderator VCDS Map User

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    I'd suggest using Kunifer rather than copper, and thats probably what your man used.

    Afaik the pump itself is robust, the bit that fails is the electronics? If its managed 195k on derv i wouldnt be adding anything else.
     
  18. mixmaster

    mixmaster Member

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    Thanks aragorn I think you are correct on both cases.

    However, the article is an interesting read for those interested...2-stroke oil and diesel


     
  19. TeKnodriver

    TeKnodriver Biodiesel Purrrr

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    Interesting...
    never heard of adding that before!
    was aware of the low-sulphur problems from TDi Club forums but I'd only ever heard of adding 10-20% biodiesel.

    I'm running 90% bio and 10% diesel for the winter,

    not sure the 2stroke will mix with this - anyone tried it?
     
  20. mixmaster

    mixmaster Member

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    Where are you buying your bio-diesel. I would like to run mine on it but it's getting hold of the stuff!

    If you read on in the article they argue that 2-stroke oil has better lubricating properties than 10% bio-diesel. I haven't read far enough to find out if they recommend adding 2-stroke oil to biodiesel.

    They don't recommend using it in older, high mileage PD engines but AFAIK the 2.5tdi AFB engine isn't.
     
  21. TeKnodriver

    TeKnodriver Biodiesel Purrrr

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    had a bettre read of related threads...
    the chart on the thread I was looking at suggested that 2% bio had the best lubrication of fuels tested:
    2Stroke oil/ diesel mixture anyone? - Page 2 - TDIClub Forums

    I get fuel from Purefuels in North London -
    run for 10K in AHU Golf and 5K in AFN A4 with no probs, though you will need to change the fuel filter soon after use maybe a couple of times.
    Not sure about it in PDs - that's why I didn't buy one!- but rotary pump should be fine -
    again, check the alternative fuel section of ClubTDi for more info
     
  22. mixmaster

    mixmaster Member

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    The 2.5tdi V6 - AFAIK its not PD but is it Common Rail or neither?
     
  23. adamss24

    adamss24 Well-Known Member

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    Old thread -i know- but just for reference, the v6 is a VE engine with pressures comparable with the PD injectors. Very, very high tech back in the day and still a dark art to tune today. Very capable and able to supply up to 1000 Bhp worth of Cummins 6L engines so there's massive potential, just the re-builders aren't too clued up on how to tweak it other than per stock Bosch settings ! By fitting larger nozzles the fueling maps get thrown out of specs so a quick fix is by raising pop pressures in order to eliminate idle shudder.
     

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