What the F£CK!!!!

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  • Mark Halligan
    S2Forum Fiend
    • Jul 2003
    • 2001
    • Country: England

    #1

    What the F£CK!!!!

    Have a look at this, and welcome to Marky boys bad dream,

    The new motor was running fine during for the first 2K miles following the re-build, both during the run in period and after.
    I ran it in on mineral based 10/40 oil to bed in the rings and then onto RS10w/60 following that. A total of five oil changes during the first 2k miles.
    The car went well when nailed, as it did before the re-build, but with almost no lag, gobs of torque and no knock or hesitation.
    We did the re-map a few weeks ago and it was fitted with the mahoosive 57lb/hr 599cc Siemens injectors.
    The session went well with the exception of one incident when a hose coming loose from the turbo to the WGFV caused the motor to overboost and produce enough torque to slip the clutch at 80 mph; this was my fault entirely as I can’t have tightened it up properly. But that was sorted quickly and the hose was tightened.

    The car really performed and went like a scalded cat, even with three up (Mihnea, Greg S and me), and a full tank of gas, following that session I was well happy with it, and went home grinning like a nutter.

    The next morning I started the car and I noticed a knocking sound which was worse when cold, being a bit paranoid about my lovely new engine I didn’t drive it too far, just far enough to make sure I wasn’t hearing things. I then dropped the sump and checked the bearings (even changed the big-ends) but it still did it.
    I left it a couple of weeks as I had no time to do anything until last Wednesday when I took the head off of it, I was wondering if I was getting piston slap and wanted to check the bores and today I dropped the sump again and popped out the pistons.

    I still have no idea what the noise I was hearing was, but I am glad I heard it in a way, as I would never have taken the motor apart, and what I found on two of the pistons has sort of stopped me dead in my tracks.

    My ‘lovely’ JE pistons, numbers one and five, have both partially melted around the valve pockets! The other three are fine. The bores are thankfully OK (amazing really the way my luck seems to be going) with no damage.
    One thing I have noticed about the JE’s is that the area that has melted is very thin and when compared to a standard piston, and it is plain to see that this thin area in the standard piston is machined away and the sharp edge is flattened out nicely. The JE’s are not like this, indeed the pistons look like they have just had the valve pockets machined into them and then they are taken off of the CNC and left as is.

    Why has this happened?
    Has this happened because of the design of the piston?
    Why has it only happened on two?
    Has it happened because of something I have done wrong?

    Any comments, ideas and p!ss taking (Tom) welcome, as I am not to sure where to go from here, other than turning the whole lot into an expensive bonfire!

    Funny I am quite calm about the whole thing, although I’m not sure how long that will last.

    Now where did I put that beer?
    Attached Files
    Mark - Modded
  • Mark Halligan
    S2Forum Fiend
    • Jul 2003
    • 2001
    • Country: England

    #2
    Another
    Attached Files
    Mark - Modded

    Comment

    • Mark Halligan
      S2Forum Fiend
      • Jul 2003
      • 2001
      • Country: England

      #3
      Here is one of the ‘good’ JE’s showing the sharp area that burnt out on the other two.
      Attached Files
      Mark - Modded

      Comment

      • Mark Halligan
        S2Forum Fiend
        • Jul 2003
        • 2001
        • Country: England

        #4
        Here is a standard piston, this clearly shows how this problem was anticipated and the area machined away to prevent over heating and burning out.
        Attached Files
        Mark - Modded

        Comment

        • Doug_RS2
          S2Forum Possessed
          • Jul 2003
          • 3847
          • Home: Scotland Current: England

          #5
          Are the centre pistons that brown down the side of them?
          S2,RS2,S4 WB,RS4,S4 B8,RS6 C5,RS6 C6,R8

          Comment

          • Mark Halligan
            S2Forum Fiend
            • Jul 2003
            • 2001
            • Country: England

            #6
            Originally posted by Doug_RS2
            Are the centre pistons that brown down the side of them?
            Yes they are, but I would expect that, as the combustion gases travel down the side of the pistons and get stopped by the rings and I would be suprised if the gasses didn't turn the Aluminium a little brown. I would be worried if this 'browning' was down below the second ring though as this would show a lot of blowby.
            I had no problems with blowby coming out of my catch tank at all and used no oil either.
            Mark - Modded

            Comment

            • audiman
              S2Forum Freak
              • Jul 2003
              • 4827
              • Country: United Kingdom

              #7
              When you phoned me and described the state of the pistons i was shocked. I thought first of all that it was a typical Mark H exageration!! LOL

              But bloody hell, they are fooked!! IMHO, the design is a bit poor, that thin edge is very very close to the edge of the crown. I wouldnt like to say what has happened there, but in my view it looks like the end cyls have been eaten away and not melted.

              This normally happens when the engine has been pinging. Dont quote me on that as i havent seen that many pistons taken from cars that have been pinging.

              Also it looks like that one piston (pic2) has 'scratched' the bore. Is the bore damaged??
              sigpic
              Tom C - www.rcmr.co.uk
              Audi UR Quattro
              Audi 100 C3 2.0 5 cyl 115ps
              Audi S2 - 07k engine project aiming for 800ps
              Audi B5 RS4 645ps 911nm

              Comment

              • audiman
                S2Forum Freak
                • Jul 2003
                • 4827
                • Country: United Kingdom

                #8
                Thats a definate hotspot on the pistons. That could cause pinging in itself. The rings look like they have bedded in nicely tho. Would be interesting to see what Dougs look like!!
                sigpic
                Tom C - www.rcmr.co.uk
                Audi UR Quattro
                Audi 100 C3 2.0 5 cyl 115ps
                Audi S2 - 07k engine project aiming for 800ps
                Audi B5 RS4 645ps 911nm

                Comment

                • Mark Halligan
                  S2Forum Fiend
                  • Jul 2003
                  • 2001
                  • Country: England

                  #9
                  Originally posted by audiman
                  Also it looks like that one piston (pic2) has 'scratched' the bore. Is the bore damaged??
                  Tom,

                  no the bores are not scored at all which suprises no one more than me, considering whats happened.
                  Mark - Modded

                  Comment

                  • Mark Halligan
                    S2Forum Fiend
                    • Jul 2003
                    • 2001
                    • Country: England

                    #10
                    Originally posted by audiman
                    Thats a definate hotspot on the pistons. That could cause pinging in itself. The rings look like they have bedded in nicely tho. Would be interesting to see what Dougs look like!!

                    A mate of mine was around earlier, he used to build a lot of engines (mainly minis) he reckons that the design is ***** too.
                    He also said and I think he is right, that they can still be used after they have been machined like the standard ones to take away the burnt areas on the fooked ones and the sharp areas on the others.

                    Funny enough I don't think I much problems with pinging at all
                    Mark - Modded

                    Comment

                    • audiman
                      S2Forum Freak
                      • Jul 2003
                      • 4827
                      • Country: United Kingdom

                      #11
                      Yeah i was thnking that too about reusing them once machined properly. But why have only the end two done it tho????

                      MY theory is that :-

                      1)the gasses are either not getting out of the manifold quick enough on those end cyls (which i find hard to believe with the SQ EM)

                      2)the inlet air is not being distributed equally due to the inlet manfiold design, causing poor mixture on the end cyls, and maybe running lean or pinging on just those cyls?

                      Just a thought, no point in repairing the pistons without finding out what caused the damage.
                      sigpic
                      Tom C - www.rcmr.co.uk
                      Audi UR Quattro
                      Audi 100 C3 2.0 5 cyl 115ps
                      Audi S2 - 07k engine project aiming for 800ps
                      Audi B5 RS4 645ps 911nm

                      Comment

                      • Doug_RS2
                        S2Forum Possessed
                        • Jul 2003
                        • 3847
                        • Home: Scotland Current: England

                        #12
                        My old pistons, that looked like they had been attacked with a centre punch, were marked a lot more in the valve recesses than anywhere else.
                        .
                        S2,RS2,S4 WB,RS4,S4 B8,RS6 C5,RS6 C6,R8

                        Comment

                        • Doug_RS2
                          S2Forum Possessed
                          • Jul 2003
                          • 3847
                          • Home: Scotland Current: England

                          #13
                          This old piston had no ping marks - apart from in the recess for the valves
                          Attached Files
                          S2,RS2,S4 WB,RS4,S4 B8,RS6 C5,RS6 C6,R8

                          Comment

                          • audiman
                            S2Forum Freak
                            • Jul 2003
                            • 4827
                            • Country: United Kingdom

                            #14
                            Well if thats what pinging looks like then Marks must have been running too hot
                            sigpic
                            Tom C - www.rcmr.co.uk
                            Audi UR Quattro
                            Audi 100 C3 2.0 5 cyl 115ps
                            Audi S2 - 07k engine project aiming for 800ps
                            Audi B5 RS4 645ps 911nm

                            Comment

                            • Mark Halligan
                              S2Forum Fiend
                              • Jul 2003
                              • 2001
                              • Country: England

                              #15
                              Originally posted by audiman
                              Well if thats what pinging looks like then Marks must have been running too hot

                              I don't think its that easy really to compare the two types of piston as they are made of different materials, and there are no sharp valvepocket edges on the standard design.

                              The damaged JE's have NO other markings on them other than the burnt out areas. Remember also that they have been ceramic coated, maybe that has something to do with it, perhaps the heat that would normally be soaked up by the crown went to the weakest area i.e. the poorly designed sharp edge on the valve cut outs?

                              Still doesn't explain why those two went and the others didn't though??
                              Mark - Modded

                              Comment

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