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servicing my 550 section 2

Discussion in '456/550/575' started by dersark_painclinic, May 10, 2020.

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  1. dersark_painclinic

    dersark_painclinic Formula Junior

    Mar 8, 2005
    981
    Glendale, CA
    Full Name:
    Lazik Der Sarkissian
    #1 dersark_painclinic, May 10, 2020
    The rear engine timing marks are picture #1,#2#3#4 , as you see the right exhaust cam rear section does not have marks since the timing sensor is there.
    After I found the TDC at firing and recorded the timing marks I was interested to find out the belt tension I set 5 years ago. Interestingly the belt tension readings varies at different positions engine stops.
    These are the initial readings at true TDC firing. I used to different system to check the tension. The Motoreva MT-112 for $ 250 and Gates tensioner apps for $ 1 on I phone. these are the findings. Gates recommend using microphone but I use without.

    Motoreva readings, Gates tension meter
    Right bank long side of belt 94 HZ 94.7 HZ
    Right bank short side of belt 118 HZ 118 HZ
    Left bank long side of belt 99 HZ 100.3 HZ
    Left bank short side of belt 89 HZ 90 HZ


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  2. flash32

    flash32 F1 Veteran

    Aug 22, 2008
    6,945
    Central NJ
    Full Name:
    Dominick
    #2 flash32, May 11, 2020
    Swag here .. if the belt is old maybe the difference in the location shows where the engine normal is at rest and the belt is "more" stretched at that position .. maybe at rest that part of the belt is around a pulley or pushed by tensioner ..just a SWAG

    Sent from my moto g(7) using Tapatalk
     
  3. AVIMAX

    AVIMAX Formula Junior

    Aug 5, 2014
    710
    Toronto
    Full Name:
    Ryan
    #3 AVIMAX, May 11, 2020
    WSM advises to check belt tension for bank 1-9 with cylinder 1 at TDC and cylinder 7 at TDC when checking bank 7-12.
     
  4. AVIMAX

    AVIMAX Formula Junior

    Aug 5, 2014
    710
    Toronto
    Full Name:
    Ryan
    #4 AVIMAX, May 11, 2020
    That should be TDC of the compression stroke.
     
  5. fatbillybob

    fatbillybob Two Time F1 World Champ
    Consultant Owner

    Aug 10, 2002
    29,026
    socal
    #5 fatbillybob, May 11, 2020
    Wow those are close! Nice to know the ap is so good. When you set the tension what freq will you use?
     
  6. dersark_painclinic

    dersark_painclinic Formula Junior

    Mar 8, 2005
    981
    Glendale, CA
    Full Name:
    Lazik Der Sarkissian
    #6 dersark_painclinic, May 11, 2020
    I speak only for my car, having her for 15 years, timing belt tension on the long side on a good days between 80-100 HZ and on bad days non recorded. Again in my experience I seen wide range of recordings which doesn't make sense and the engine still surviving. most probably when you rev the engine to higher RPM then tooth jumping is more prominent issue. I am going to set 80-100 on the log side for normal driving which I do. Again warn me if I am off.
     
  7. dersark_painclinic

    dersark_painclinic Formula Junior

    Mar 8, 2005
    981
    Glendale, CA
    Full Name:
    Lazik Der Sarkissian
    #7 dersark_painclinic, May 11, 2020
    Ryan, I checked the belt tension for BOTH banks when the cylinder #1 was at TDC, I don't see any differences on my recording my be old belt. but you are right WSM recommend doing at #1 and #7 cylinder. I will do that when it comes to replace it.
     
  8. AVIMAX

    AVIMAX Formula Junior

    Aug 5, 2014
    710
    Toronto
    Full Name:
    Ryan
    #8 AVIMAX, May 12, 2020
    The only difference I can see is that when the cylinder closest to the belt is at TDC on compression, all valves are closed meaning the lobes of both the intake and exhaust camshafts are riding on their base circles, not on the raised part of the lobes, so it would be the case of minimum pressure exerted from the valve springs on the camshaft away and therefore I suppose the belt tension would be at its minimum. That said, I suspect the difference if not at TDC would be minimal, but I haven't tried checking it at other positions to confirm.
     

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