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  • #16
    Originally posted by Aaron on December 10, 2013 7:18 AM
    Wil
    I agree - that whirring sound described, "sounds" like the sound when the tensioner is too tight, and is where I back the tensioner out to make go away.
    When the chain is too loose, I would describe it as more of a clacking and it definitely changes as the engine is reved and dropped back to idle (idle to 2000) rpm.
    I will re-iterate, I believe the chain play is a hard adjustment of the location of the tensioner shoe and the spring is just there to take that small amount of
    excess. So I think you have done it correctly if you back out your quarter turn from where the whirring goes away.

    When I had the covers off, pushing with a gloved thumb on the chain between the left cams, I could feel the chain tighten as I turned in the tension adjustment.
    I could press on the chain, compress the spring in the chain tensioner and tighten it up against the chain "hard stop" location. When the chain is flying around
    at 6000 RPM, I'm sure the forces are much greater than my thumb, which is how I justify my belief that the tension is not a function of the spring, but a function of
    the location of the where the tension shoe can not move anymore.

    I'm at loss as to why you do not have an intermediate "quiet adjustment" . Could there be something else contributing to the BB on the wash board noise,



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    • #17
      Originally posted by 365Lusso on December 10, 2013 3:31 PM
      Aaron,
      Your second time around describing the chain issue made it click. I wasn't letting go of the idea that chain tension is correctly set by spring tension alone: it is actually set by the fully bound/compressed spring stack (minus 1/4 turn for play). That would explain the very brief turning range (one turn in this case) from humming tight to clacking loose. That was really bugging me. The spring by itself is not strong enough to hold proper chain tension, so the chain will clack--or worse--throughout most of its adjustment range. The chain will clack until the spring is all the way compressed.
      My engine does the same thing when the chain is too loose--the clacking goes and comes back when revved and dropped back to idle.

      Thanks much--that was great to have the light bulb go off,
      Wil
      Originally posted by Aaron
      When the chain is too loose, I would describe it as more of a clacking and it definitely changes as the engine is reved and dropped back to idle (idle to 2000) rpm.
      ........my belief that the tension is not a function of the spring, but a function of the location of the where the tension shoe can not move anymore.

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      • #18
        Originally posted by Ian Levy on December 10, 2013 7:32 AM
        Aaron
        Interesting for me is the huge difference between early to late chain tensioners.
        It looks to me that the early version(pre 15181 & 15289) is of lighter construction as is the original oil/water pump chain tensiner.
        The late tensioner looks to be considerably bigger with a much,much heavier spring.
        How did the early arrangement manage to put sufficient pressure on the chain?
        Ian L

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        • #19
          Originally posted by Trachsel on December 10, 2013 5:55 PM
          Hi all, first of all check which tensioner your car has. If it is the tensioner of the second serie, compare TAV 6, Fig 8 with http://www.eurospares.co.uk/userImag...ge/064_006.gif . (Tensioner housing) You can see, that 365 gt 4 2+2, the succeder of our 365 gtc4,there is the difference, that you cannot fix the tensioner. My car, 16 273, has allready the modification for the 365 gt 4 2+2. So, when I changed the chain, I made the mistake, not to take out the cams first. When I opened the chain, the tensioner spring pushed the tensioner and the chain turned the cams - 4 valves destroied ! Please pay attension, late cars will have the modifications for gt 4 2+2. Regards, Jacques

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          • #20
            Originally posted by 365Lusso on December 11, 2013 7:02 PM
            Jacques, thank you for sharing with me your hard-earned experience. My chassis (16251) is very close to, and has the same later tensioner housing as yours. I don't have any plans to replace the chain, so it won't be a problem. Regards, Wil

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