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Oil Pump PROBLEMS! m20 2.7

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    #16
    Originally posted by h82crash View Post
    I don't think the engineer would design the torque to turn procedure that far into the plastic range of the bolt, but I'm not afraid to admit I could be wrong.
    Hello Tom,

    I see you did NOT take the time to read the article I left you a link to for your own research. But I understand research on a critical engine component you apparently know nothing about is too much to ask.

    So let me quote a small peice of the article you missed out on.

    Unlike a conventional bolt, TTY bolts are tightened beyond their elastic range past their yield point from which the bolt material can recover to its original length, and into the plastic phase of the bolt material. The bolt is permanently stretched and for this reason should not be reused. The reliability of these bolts once stretched is greatly reduced.

    Comment


      #17
      Robert, you and the Mad guy make a lot of assumptions. I think it's a communication thing. Leads to a lot of divorce in this country.

      I guess I wasn't clear. I do understand the concept. I am not advocating to anyone else who is assembling an engine to deviate from procedure. I was just looking for some opinions other than status quo-I read it somewhere on the internet. Anyone out there with pull test data, comparisons between used bolts or new ones?

      The article you quote doesn't mention that steel, once in the plastic range still has a ways to go before it reaches ultimate tensile strength.

      The article also does not address the fact that the specs take into account a sometimes huge safety margin based on product liabilty. Of course an engineer, with his reputation and career on the line is going to recommend replacing the bolts- wouldn't even be a cost factor for the MFR. It's a no brainer.

      Just looking for some informed data and discussion without insults...
      "Life is hard...it's a lot harder if you're stupid."

      Tom
      72 2002
      87 327i
      88 525i
      88 535i
      03 530i

      Comment


        #18
        Originally posted by el maestro View Post
        Im not trying to retorque them, i took the cap of the end of the rod too check the bearings and i dont see anything in the chiltons manual i have.
        And therefore you will have to retorque them!
        You will HAVE, not 'should', but HAVE TO replace the bolts now, they are one-time use.
        1989 cirrisblau-metallic 325i

        Comment


          #19
          oh wow I just read the rest of the thread now, owch

          just replace the damn things and stop measuring your e-cock
          1989 cirrisblau-metallic 325i

          Comment


            #20
            I just remembered, where can I get rod bolts for $8 a pair? Are the web sites in error when they list the price as each?

            Some figures...

            Retorqued rod bolt per procedure 4x. Each time @ 70* the torque was 42-47 ftlbs.
            bolt length was unchanged 61.96mm

            Same bolt overtorqued 2x to 150* Torque value was around 60.
            After overtorque the bolt length was 62.22

            I do not have camping figures or tensile tests but @ 60 the clamping force has to be much higher than @ 45. Also this bolt still had not reached ultimate tensile strength.

            Overtorqued a different bolt to 150* for the first "retorque". It reached about 52 ftlb.
            Bolt length was 62.05mm

            Torqued the first bolt for the seventh time to 70* and torque was 45 ftlbs.

            Sounds to me like a pretty good safety margin for bolt strength.
            "Life is hard...it's a lot harder if you're stupid."

            Tom
            72 2002
            87 327i
            88 525i
            88 535i
            03 530i

            Comment


              #21
              That was an interesting test, but I don't know that it means a lot for this application. You need to do the test with several new bolts, checking the length before torquing, while under load, and after the load is removed.
              The car makes it possible, but the driver makes it happen.
              Jim Levie, Huntsville, AL

              Comment


                #22
                Yes, it would be nice. For this application we need to know what the required clamping force is and the ultimate tensile strength of the bolts.

                In my former career, non-destructive and destructive mechanical testing and inspection, I would have access to a machine to conduct pull tests. It's been 13 years since I've worked in that field so it would cost me more than a new set of bolts.
                "Life is hard...it's a lot harder if you're stupid."

                Tom
                72 2002
                87 327i
                88 525i
                88 535i
                03 530i

                Comment


                  #23
                  Haha damn this is still alive....I ended up replacing them with new ones....one thing they were cheap and another was peace of mind. Thanks to those who helped out and to the first guy that told me about them i just wanted to make sure thats why i kept asking. But my shits running fine now HOORAY!

                  Comment


                    #24
                    Why not just get same bolts, but 12.9 grade capscrews ? these should be cheaper then BMW bolts... and you could probably safely torque it to 60ftlbs....

                    Comment


                      #25
                      I found some BMW bolts for $65/set. Cheapest I could find. A friend is a mgr at a parts supply and his cost was $102. I love BMW's but they are very proud of their parts.
                      I build VW's and I can get a new set of piston/cylinders/rings for $150. The gasket set for the entire motor-a whole $14. Big contrast.

                      So my gaskets and bolts for this 2.7 stroker I'm putting together cost the same as the full rebuild of a VW.
                      "Life is hard...it's a lot harder if you're stupid."

                      Tom
                      72 2002
                      87 327i
                      88 525i
                      88 535i
                      03 530i

                      Comment


                        #26
                        Originally posted by h82crash View Post
                        I found some BMW bolts for $65/set. Cheapest I could find. A friend is a mgr at a parts supply and his cost was $102. I love BMW's but they are very proud of their parts.
                        I build VW's and I can get a new set of piston/cylinders/rings for $150. The gasket set for the entire motor-a whole $14. Big contrast.

                        So my gaskets and bolts for this 2.7 stroker I'm putting together cost the same as the full rebuild of a VW.
                        labor in mexico is a lot cheaper than it is in europe. ;)
                        Build thread

                        Bimmerlabs

                        Comment


                          #27
                          Yup
                          "Life is hard...it's a lot harder if you're stupid."

                          Tom
                          72 2002
                          87 327i
                          88 525i
                          88 535i
                          03 530i

                          Comment

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