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360 Timing Belts

Discussion in 'Technical Q&A' started by alex360S, May 20, 2012.

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  1. alex360S

    alex360S Formula Junior

    Oct 30, 2006
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    Alex
    #1 alex360S, May 20, 2012
    Just finished timing belt job and after a 15 min idle check once I stopped it I noticed that the tensioner pulley holder has retreated and is now touching the bracket holder. Basically the small gap that exists once tensioned and adjusted does not exist anymore. Is this normal ? Just want to be sure before I put the timing cases back on. Any input would be greatly appreciated.
     
  2. alex360S

    alex360S Formula Junior

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    #2 alex360S, May 20, 2012
    Also wanted to know if it's normal that the belts get very hot ? I would assume so at those RPMs but just to be sure.
     
  3. alex360S

    alex360S Formula Junior

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    #3 alex360S, May 20, 2012
    Anyone?
     
  4. rustybits

    rustybits F1 Rookie
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    #4 rustybits, May 21, 2012
    Did you set the belt tension with a tension guage? That platform shouldn't bottom out, although the gap will vary according to whereabouts in the cycle the valves are when the engine is stationary. And yes, the belts will get hot.
     
  5. alex360S

    alex360S Formula Junior

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    #5 alex360S, May 21, 2012
    Thanks for your reply. Yes I did set the tension with a gauge with the lock pin in place during the setting. I had 202hz on the left bank and 205hz on the right. After the adjustment the lock pin remained free to move in and out of the hole so I figured all was right and exactly as the WSM. After having met those conditions the gap is quite small. Is it possible that the belts expand during operation and thus bottom out the tensioner?
     
  6. alex360S

    alex360S Formula Junior

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    #6 alex360S, May 21, 2012
    Just realized that it is not possible to tension the belts with lock pin in place and attain the 1.9-2.3mm gap between the tensioner arm and holder. Is the manual wrong? Can I re-tension with the same belts or do I have to scrap them?
     
  7. FerrariDublin

    FerrariDublin F1 Rookie

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    #7 FerrariDublin, May 21, 2012
    Is it possible that when tightening up the locking bolt on the tensioner pulley that the pulley slipped, thereby pushing against the belt to a greater extent and thereby pushing the hydraulic ram further back into the housing?

    Not absolutely sure I follow but assuming you are happy with your timing marks my inclination would be to re-do the tensioning part of the work.

    As I understand it there are "tighter" and "looser" periods for the belts depending on where you are in the cycle but my reading is that regardless of where you are in that cycle you should have that that minimum gap of 1.9mm remaining so that the hydraulic tensioner can "give" a little when it needs to.

    As regards continuing to use your belts I feel that if they had somehow been stretched that your problem would be at the other extreme - i.e. you would be outside the 2.3mm tolerance.

    Are you seeing this lack of clearance on both sides or only one?
     
  8. alex360S

    alex360S Formula Junior

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    #8 alex360S, May 21, 2012

    Thanks for your reply Greg. The lack of clearance was on both sides. The manual is definitely wrong. You cannot tension the belts with the lockpin in place and expect the 1.9-2.3mm clearance. I've redone the tension and attained the required clearance and also attained a around 205hz on both belts. At the required clearance the pin can go through the holder and piston but not through the back end. I believe that manual was badly translated. Please correct me if my theory is wrong.
     
  9. FerrariDublin

    FerrariDublin F1 Rookie

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    #9 FerrariDublin, May 21, 2012
    Sorry, it's all theory and reading for me to date. I've not taken on this job yet myself.

    Happy to give you a bump though while waiting for a pro to chime in!
     
  10. Mitch Alsup

    Mitch Alsup F1 Veteran

    Nov 4, 2003
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    #10 Mitch Alsup, May 21, 2012
    Due to the load carried in the belts, they will operate slightly above the temperature at the front of the engine. Thus, they will be hotter than the covers and the aluminum block.
     
  11. Skidkid

    Skidkid F1 Veteran
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    #11 Skidkid, May 21, 2012
    Hadn't considered it but I believe that they get hot. However, it probably isn't because of the load. The belts are constantly flexing around the pulleys. In essence, the inner surface is compressed and the outer is stretched (slightly but stretched none the less). The work dissipated in flexing is what is causing the heating.
     

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