Updated Cambelt info.
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  1. #1
    Moderator Alan S's Avatar
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    Icon4 Updated Cambelt info.

    I've just posted this write up in the archives that may be of interest to anyone with an engine that runs a cambelt.


    http://www.aussiefrogs.com/forum/sho...836#post273836

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    Alan S
    If it ain't broke, use a 12" shifter.....that usually does the trick!!

  2. #2
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    Alan,

    I recently had a new cam belt and tensioner, crank/cam seals replaced (whilst replacing leaking water pump) on my VW Caravelle 2.5.

    Now there is a this noticble belt whine noise most prominant at 2000 RPM.

    The garage fine tuned twice with no success. They used two methods...the old 90 degree belt twist method, and the official method of alining two lugs on the belt tensioner. The latter made it worse!

    Further loosening would have posed further risks of jumping a cog particuarly on de-acceleration.

    Not sure what the next steps should be, or just turn put up with the noise.

    I was also told at the time,that new generation belts will not stretch, only snap!!

    Regards,

    Scott

  3. #3
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    Thanks Alan - really appreciated.


    2003 PEUGEOT 206 GTi

  4. #4
    Moderator Alan S's Avatar
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    Scott,

    I did the belt on a BX 8 valve engine yesterday/today as there were a couple of things I wasn't 100% happy with, but at the end of it all when I was, I started it up minus hydraulic pump just as a test and no whirring.
    The most common cause is incorrect tensioning, however it is almost scarey the lack of knowledge of the intricacies of these belts amongst the parts and repairers and for one thing, they are directional. They also have a myriad of profiles and an incorrect profile will also make it noisy.
    We recently did a 24 valve conversion on a Holden Commodore which necessitated us having to find a belt with the correct specs to to suit the job; what a bloody nightmare that was. The correct profile will sit and seat neatly into the sprockets on the cogs. It won't ride high nor bottom with daylight above and it won't show a gap between the sprocket and the belt teeth that the belt was doing on the car I just changed it on.
    In the case of Mi16/BX16V engines, rotating the tensioners the wrong way will also cause a whirring due to the belt feeling as though it's tensioned correctly when tested as per specs but due to the location of the tensioners, it causes excess tension between two other points on the run.
    I agree, that non stretch belts may tend to snap due to overtensioning, however, in my opinion, any belt that whirrs has a problem and in the interests of engine life it should be found and rectified.


    Alan S
    If it ain't broke, use a 12" shifter.....that usually does the trick!!

  5. #5
    Fellow Frogger!
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    Great information. Thank you.
    Puggy.

  6. #6
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    Quote Originally Posted by Alan S
    Scott,

    I did the belt on a BX 8 valve engine yesterday/today as there were a couple of things I wasn't 100% happy with, but at the end of it all when I was, I started it up minus hydraulic pump just as a test and no whirring.
    The most common cause is incorrect tensioning, however it is almost scarey the lack of knowledge of the intricacies of these belts amongst the parts and repairers and for one thing, they are directional. They also have a myriad of profiles and an incorrect profile will also make it noisy.
    We recently did a 24 valve conversion on a Holden Commodore which necessitated us having to find a belt with the correct specs to to suit the job; what a bloody nightmare that was. The correct profile will sit and seat neatly into the sprockets on the cogs. It won't ride high nor bottom with daylight above and it won't show a gap between the sprocket and the belt teeth that the belt was doing on the car I just changed it on.
    In the case of Mi16/BX16V engines, rotating the tensioners the wrong way will also cause a whirring due to the belt feeling as though it's tensioned correctly when tested as per specs but due to the location of the tensioners, it causes excess tension between two other points on the run.
    I agree, that non stretch belts may tend to snap due to overtensioning, however, in my opinion, any belt that whirrs has a problem and in the interests of engine life it should be found and rectified.


    Alan S
    Alan,

    Thanks for the info...much appreciated. I need to delve further and get to the bottom of what is going on. Interesting point re the profiles...makes me also wonder whether an aftermarket belt was fitted, or put on in the wrong direction. Alternatively, whether the water pump cog has a different profile.

    Cheers,

    Scott

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