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  • Burning oil

    Hello, I am loosing oil in my UR. Engine has been rebuild some time ago and it has done around 5k miles also I have new turbo 2k miles (one of Norway finest )
    Engine is smoking on start up, when driving there is no visible smoke but still oil level goes down. Before I remove engine I would like to send turbo to be checked, do we have any good turbo work shop in south east/London area anyone could recommend?
    Regards
    sigpic_________
    Rob

  • #2
    This topic recently been covered on this thread.

    https://www.s2forum.com/forum/techni...to#post2093449

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    • #3
      I’m no expert on this, but smoking on start up suggests oil is entering the chambers during the heat cool down. My personal experience of turbo oil seal failure is perfect (no smoke) cold start up and ‘smoke’ once the oil warms up to bypass the failing turbo oil seals. Fine when driving but smoking when left at idle.

      85 WR Urquattro, 85 20vT International liveried RallyRep
      93 MTMS2 Avant

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      • #4
        Originally posted by Ian Simmonds View Post
        I’m no expert on this, but smoking on start up suggests oil is entering the chambers during the heat cool down. My personal experience of turbo oil seal failure is perfect (no smoke) cold start up and ‘smoke’ once the oil warms up to bypass the failing turbo oil seals. Fine when driving but smoking when left at idle.
        Thanks Ian. I am thinking the same and our diagnosis was oil is getting into engine by valve seals or pistons rings but I want to start with the easiest accessible part which is turbo. I will use my local turbo workshop to see what is going on. If there is no fault found in turbo the head is next.
        sigpic_________
        Rob

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        • #5
          Originally posted by robo View Post

          Thanks Ian. I am thinking the same and our diagnosis was oil is getting into engine by valve seals or pistons rings but I want to start with the easiest accessible part which is turbo. I will use my local turbo workshop to see what is going on. If there is no fault found in turbo the head is next.
          Check the boost pipes and/or intercooler for oil. If they’re wet with oil it is getting into the induction side long before the valve stems and seals which would suggest turbo.
          85 WR Urquattro, 85 20vT International liveried RallyRep
          93 MTMS2 Avant

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          • #6
            Originally posted by Ian Simmonds View Post

            Check the boost pipes and/or intercooler for oil. If they’re wet with oil it is getting into the induction side long before the valve stems and seals which would suggest turbo.
            It's all dry in the intercooler.
            sigpic_________
            Rob

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            • #7
              That helps.

              the only deliberate way the engine gets oil into the induction is via the Positive Crankcase Ventilation System.

              There is a diagram in this post here..

              https://www.s2forum.com/forum/techni...-testing-draft

              if it’s blocked it can cause hot idle smoke. Again, not your symptoms.

              ***edit*** my mistake.... You’re talking Ur aren’t you... Apologies.
              Last edited by Ian Simmonds; 10 October 2020, 09:32.
              85 WR Urquattro, 85 20vT International liveried RallyRep
              93 MTMS2 Avant

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              • #8
                Sounds like turbo hotside or valve stem oil seals. You wouldn't expect the valve seals to be leaking if they have recently been replaced, however, if one isn't seated properly they will leak a fair amount of oil. Does the turbo require an oil restrictor to reduce pressure/flow?
                91 Modded 3B
                14 A6 Avant Black Edition

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                • #9
                  Valve stem seals test. Look for smoke when you come off the throttle going down a hill.
                  If the seals were installed without using the correct tool they may have been torn


                  ​​
                  Nothelle S2 Avant in restoration
                  Wr Ur Quattro (also in restoration)

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                  • #10
                    Sorry guys I should have put more information in the first post. The UR has 20V fully modified engine with JE's, strong con rods and mechanical follower,
                    Engine has been build about ten years ago but has not done many miles due long term build project.
                    Turbo is hybrid rs2 and breather system deleted with not much oil in the catch can. No oil leaks and on average I loose 1liter per 500 miles.
                    sigpic_________
                    Rob

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                    • #11
                      Hi Rob
                      That's a lot of oil to be losing through the valve stem seals. Have you tried a leak down test? That will give you an idea of what's going on with the rings.
                      Nothelle S2 Avant in restoration
                      Wr Ur Quattro (also in restoration)

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                      • #12
                        JE pistons = big clearance & low tension scraper rings = oil burner. You just live with it.
                        Panthero Coupé quattro 20vt
                        Indigo ABY coupé
                        Imola B6 S4 Avant

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                        • #13
                          Just done the leak down test and readings on all cylinders are 13 bars, when adding 10ml of oil, cylinder 2 and 4 showing 15 bars so decision is engine out.
                          I have used JE's and total seal rings and I wonder what has gone wrong.
                          Last edited by robo; 10 October 2020, 20:19.
                          sigpic_________
                          Rob

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                          • #14
                            Compression doesn’t sound like an issue to me.
                            Low tension oil control rings are designed to be used with dry sump systems where there is a vacuum in the crank case, they are not very useful on a wet sump engine. Add the loose clearances that JE specify and you have a recipe for oil consumption - no problem on a race engine, not so good on a road car
                            Panthero Coupé quattro 20vt
                            Indigo ABY coupé
                            Imola B6 S4 Avant

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                            • #15
                              [QUOTE=Error404;n2094555]Compression doesn’t sound like an issue to me.
                              Compression test shows 13 bars on all cylinders and then after adding 10ml of oil to cylinder bores pressure on cylinder 2 and 4 increases to 15 bar but cylinder 1,3 and 5 stays at around 13 bars. Alex do you recon this is acceptable?

                              sigpic_________
                              Rob

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