General turbo question: one for those who know about the oil system

Discussion in 'Turbocharged, Supercharged or Nitrous !' started by Jon Olds, Jul 20, 2021.

  1. Jon Olds Forum Junkie

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    Right, firstly I'm a bit stuck and need help from one or more of the experts on here.

    I have a road car (1900 TDI: D19AA engine) burning oil, badly.

    So far, this is what I've done and I've not found the source of the trouble.

    Removed the turbo and the exhaust flange outlet was very oily, the four inlet exhaust ports were ordinarily diesel sooty.

    So I presumed the turbo oil seals had leaked and took it for a new core at an established reconditioner. Also, I requested no chinese pattern parts to be used.

    Fitted it, thinking my problems would be solved. No, still a lot of blue smoke.

    No visible sign of oil entering the compressor side of things. No crankcase ventilation valve to fail, blocking the recirc line to the turbo compressor inlet made no change.

    Car drives perfectly, pulls like a train, ticks over, starts normally, just produces a huge amount of blue smoke at low stop, start speee.

    Cleaned out the exhaust system, cat, dpf, so it's not old oil being burnt.

    Checked the return path of lube to the sump, all clear, no blockages.

    Changed to thinner oil and another new oil filter, no change. Its now on 0/30W.

    Suspected excessive oil pressure, measured it and it was a bit high. Pulled sump, relief valve as new. Added a shim to lower it, a bit. (yes, I understand the risk in doing so)

    Oil supply pipe is OE and doesnt have any sort of flow restriction built in.

    Still smokes badly at idle, burns off after a few miles at speed. Appears to be 'over oiling'.

    Examined the old turbo (which had been renewed in the last year or three) only seal appears to be is a square section steel circlip type thing on the shaft. Rest is as new. No visible damage anywhere.

    Questions;
    What oil pressure at idle is 'normal' for a turbo?
    At what oil pressure at idle would cause leakage into the exhaust turbine?
    Is the steel square section 'seal' all there is?
    Does the sealing use exhaust pressure also, or what.
    How is it supposed to work, is it as simple as it appears?
    As the turbo has had a new cartridge only, is it possible to mess this up when installing?

    I have been trying to fix this now for 3-4 weeks, on and off.
    Next I'm going to buy a secondhand turbo, and try this
    Not sure what else to try ??
    HELP

    Thanks
    Jon
     
  2. Savagesam

    Savagesam Moderator Staff Member Moderator

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    It’s not a deeper issue is it? Piston rings or something is it?
     
  3. Tristan

    Tristan Paid Member Paid Member

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    As Sam said Jon, are you confident it's not rings, or valve seals?
    Generally the FIAT diesels are pretty good.
     
  4. Vinnie Paid Member Paid Member

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    Did you clean the boost side
    intercooler boost pipes. Had a turbo fail on a Audi and it took awhile to clean
     
  5. Jon Olds Forum Junkie

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    Thanks guys. All 4 exhaust ports are dry are ordinarily sooty. Turbo exhaust outlet is swimming in fresh unburnt oil. Hence the smoke when the cat gets hot enough to start burning it. Backpressure at rocker box minimal, vent pipe from rocker box minimal oil. Yes, i cleaned all ic pipework and ic itself but wasnt particularly oily or dirty. Ic did not have liquid oil in , worth mentioning. Think the turbo will have to come off again for inspection or replacement. This engine is fitted to suzuki vauxhall saab etc and doesnt seem to have a bad rep. This car of mine is lowish mileage and top book condition hence me spending the time to fix it. Have never done a compression test on a diesel perhaps thats a possibility? Or shove a boroscope down also? Nothing points to the oil getting burnt in the cylinders, so far……
     
    Vinnie likes this.
  6. Jon Olds Forum Junkie

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    The genuine manual quotes 15psi at idle and 60psi at 3000rpm. At normal operating temp. Oil pump lube spec. Seems very low to me. Four big heavy pistons overcome 20:1 compression. If the oil pump relief valve is not stuck shut, and the bottom end inside appears mint, engine is quiet, there is no reason i can see to replace the oil pump. Can a turbo keep its oil inside the plain bush thing if there is say 50psi at idle???
     
  7. Vinnie Paid Member Paid Member

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    Can you take the char out and run the engine see if the oil runs past just a thought
     
  8. Jon Olds Forum Junkie

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    I can run it as a non turbo, by leaving the pipework off the compressor and routing the AFM direct in line to the intake. I have done this
    and its still smokey. Which confirms to me that the oil is not entering the combustion chamber via the compressor. I would like to run without the exhaust turbine connected and with the oil supply blanked, but this is difficult to rig up, would need a non turbo exhaust manifold. I have run the engine without any cat and exhaust on so you can see the exhaust impeller on the turbo outlet spinning. It spins and after 5 minutes at tickover the impeller is sitting in its own little oil bath. Confirming no doubt (to me) that oil is getting past the seals from the lube supply to the exhaust. There can only be three reasons for this, that I can see;
    1. Oil pressure is too high, overcoming the seals
    2. Oil is not draining back to the sump, so the cavity is flooding (I have already done everything to confirm this is not the case)
    3. Turbo seals are faulty or not compatible to this vehicle

    Either 1 or 3 is correct, I think. If I'm a betting man, more likely 3.
    Jon
     
  9. Jon Olds Forum Junkie

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    More comments welcomed, this is one of the best technical 'sounding board' sites out there....
    Thanks
    Jon
     
  10. Tristan

    Tristan Paid Member Paid Member

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    Spun like no3 all right, Jon, i know you are no fool.

    A slightly (!) dodgy way to check the return is to overfill the engine as much as possible, let the return flow into ideally a jug so you'd know when say a litre had returned. Obviously this has an element of risk!
     
  11. HPR

    HPR Administrator Admin

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    I tend to think its the turbo, there might be a crack somewhere and even after rebuild of the turbo the crack is still there ...
    oilpump / oil pressure seems me a bit far sought... altough ?
     
  12. Jon Olds Forum Junkie

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    Pictures sometimes help illustrate;
    sx4 coating of oil inside the cat.jpg
    Above shows fresh oil on the metal sides of the cat outlet, just below the turbo outlet. This was as clean as a whistle after removal and thorugh cleaning 10 miles ago. Also,
    sx4 oily finger rubbed inside the cat outlet.jpg
    Rubbing a finger inside the cat (ooh ahh missus) shows fresh unburnt oil. Also
    sx4 evidence of oil leaking past exhaust flange to cat outlet.jpg
    Above shows oil migrating outside the exhaust flange (being blown out) And no, to answer the question that's not asked yet, the (downstream) DPF isn't blocked, quite the contrary..
     
  13. Jon Olds Forum Junkie

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    Plumbed in my external pressure gauge into the main oil gallery and plotted pressure against time as the engine warmed up.
    Initially 75psi (averaged)
    Dropped to 30psi (averaged) after 25 minutes, when car gauge was mid way
    Linear drop, as expected
    Nothing wrong here, as far as I can see.
    As long as the turbo seals can cope with the above pressures...................
    Must be a faulty turbo?
    Anybody else?
    Regards
    Jon
     
  14. Vinnie Paid Member Paid Member

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    Sounds like Jon
     
  15. Jon Olds Forum Junkie

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    Brick wall, attempting to get over it, through it, whatever. So, turbo off again, as pics below (help still sought);
    sx4 turbo removed again overall shot 2.jpg
    above, turbo, overall;
    sx4 exhaust port 1 looking into head.jpg

    sx4 exhaust port 3 looking into head.jpg sx4 exhaust port 3 looking into head.jpg
    port 3 looking into head, slightest sign of oil on valve stem, is this significant??
    sx4 turbo removed again shoiwng 3 appaently dry exh port inlets.jpg
    view into three of the four exhaust ports apparently showing them dry......apparently
    sx4 turbo removed again oily exhaust outlet and clean egr port view.jpg
    shows egr take off point dry and turbo outlet sopping well with oil............

    Question: If the exhaust guides are shot, would the oil be carried in the exhaust gas into the turbo and not coat the exhaust ports walls of the head, then turn back into oil after the spining of the exhaust turbine wheel. (ie dry upstream, wet dowstream??)
    About to buy a secondhand turbo and return this one to the reconditioner.....
    Anybody faced this, cos its all new to me
    And I am genuinely confused (dot com)
    thanks
    Jon
     
  16. Vinnie Paid Member Paid Member

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    Is that oil on the back side of the turbo
     
  17. Vinnie Paid Member Paid Member

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    Just looks like carbon build up before the turbo then on the hot side is oil. Can you take the char off and see the oil
     
  18. Jon Olds Forum Junkie

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    Not sure what you mean by char?
    Jon
     
  19. Vinnie Paid Member Paid Member

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    Its the Center part of the turbo if the turbo is leaking from the hot side you should see it when you split the turbo EAEAFA23-2CAD-4CDE-9DF1-41FB5E3084B3.png
     
  20. Jon Olds Forum Junkie

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    Thanks, new words to me. As wil be obvious to everybody by now, my experience of turbo tech is very very limited.

    My last question, to re-word it (if anybody is listening..)

    If oil is being sucked down the exh guides on the overrun
    and is in the exhaust gas 'body' of gas, will it be centrifuged by hitting the turbo exhaust impeller so throwing it out onto the walls of the turbo exhaust exit housing ??????????
    If so, that would exactly account for the symptoms I have, and initially I was suspecting a dodgy turbo or lube system, when it could be exhaust valve guide trouble I have.
    I'm sure I can't be the first with these symptoms, surely??
    Comment appreciated, as it will directly affect where I start to spend money next.
    (This is my road car, and its effectively been off the road 6 weeks now....)
    Thanks
    Jon
     

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