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Why is my chair tensioner not tensioning ?

Discussion in 'XJ Technical Chat' started by swingmanu, Jun 19, 2022.

  1. swingmanu

    swingmanu Member

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    Hi,

    Rebuilding the engine is going well. I am now reinstalling the chain tensioner following the manual. I installed it and released the bolt (waiting to hear the chain. Tensioner tension the chain) but nothing is tightening.

    Chain doesnt seem to be tightened. Could it be tired spring?

    Any idea?
     
    Last edited: Jun 19, 2022
  2. Franz

    Franz Well-Known Member

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  3. Franz

    Franz Well-Known Member

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    Last edited: Jun 19, 2022
  4. XJ550H

    XJ550H Well-Known Member Premium Member

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    guide could be to worn to tighten chain
    plunger may not be pushing out due to a burr on the rod
     
    k-moe and Franz like this.
  5. k-moe

    k-moe Pie, Bacon, Bourbon. Moderator Premium Member

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    It would be very helpful to know the model and year of your XJ. There are two types of cam chain tensioners, and both work somewhat differently.
     
  6. swingmanu

    swingmanu Member

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    Hi, yes @Franz that's the one.
    I have an xj650 4k0 Europe. The tensioner is the manual one with locking bolt.

    Prior to dismantling the bike, the chain was tensioned properly.
     
  7. swingmanu

    swingmanu Member

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  8. swingmanu

    swingmanu Member

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  9. Franz

    Franz Well-Known Member

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    Well if the plunger is faulty on your tensioner as @XJ550H suggested you are better getting an automatic one. Did you check the tensioner? Guide should be fine if the chain was tensioned property before.
     
    Last edited: Jun 20, 2022
  10. Franz

    Franz Well-Known Member

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    KO setup. Just wondering if there is a burr on your tensioner?

    https://images.cmsnl.com/img/partsl...300e1-camshaft-chain_big3IMG00996390_7fce.gif

    I posted a picture of the exhaust side chain guide for you where the guide goes into the pocket on the crankcase. The chain side guide if the bolt is too tight prevents the guide moving forward properly, well that's what l found. On my 900f engine l tightened the bolt B until it seated against the bottom of the chain guide. Then I backed the bolt off a quarter of a turn and tightened the locknut A.

    16557173726876722199101697879497.jpg

    I cannot be sure this would stop it tensioning the chain but worth checking anyway, especially as it was all working before you rebuilt the engine. Just checking if you followed the procedure outlined above?
     
    Last edited: Jun 20, 2022
  11. swingmanu

    swingmanu Member

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    Ok this is interesting I didn't think I'd have to mess with that bolt. I only replace the head gasket that was broken so I didn't go further now dismantling and when rebuilding I just reinserted the chain tensioner as described in manual but now I see there is maybe more.

    What is a burr on the tensioner? I'm confused with the term
     
  12. Franz

    Franz Well-Known Member

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    A projection or indentation caused by manufacturing or wear. Someone else can perhaps explain better. I am no engineer but basically it is wear damage to the tensioner rod preventing the spring extending the plunger far enough to tension the cam chain I think.

    You did not disturb the tensioner blade bolt so it cannot be that as it was working fine before.
     
    Last edited: Jun 20, 2022
  13. swingmanu

    swingmanu Member

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    Right, could be. I just didn't hear a click or anything like stated in manual that would indicate that the tensioner went in proper position and I still have some slack on the chain on top. I assume, the chain should be tight
     
  14. swingmanu

    swingmanu Member

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    Maybe it's doing its job and pushing it enough and I am just confused on what I was supposed to hear and feel when installing it. The rod moves freely so it should go again the chain guide. Maybe that's all and I am overthinking this. How else could I make sure it's tensioning the chain?
     
  15. Franz

    Franz Well-Known Member

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    The chain should be tensioned when you release the tensioner. There should be no slack in the chain. When you fitted the cams did you make sure the chain was tight from the crankshaft sprocket to the exhaust camshaft sprocket? All the slack must be between the crankshaft sprocket and the inlet camshaft sprocket. If you get the chain tight when you release the tensioner and the timing marks are spot on it should be fine. Try this fully extend the tensioner and lock it. Then try fitting it to the engine by pushing it don't fit the bolts. If the tensioner and the cylinder block do not come into contact the tensioner rod must be pushing the guide fully forward. The only way the body of the tensioner can hit the cylinder block with the tensioner fully extended and locked is if the cam chain is worn out.
     
  16. swingmanu

    swingmanu Member

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    Interesting, there lies maybe my problem. When I removed the engine, there was slack between the two camshaft. In the middle section... So I assume that was normal. Otherwise also I don't know how someone can replace the camshaft with the chain in place... so maybe that's the issue.
    I'll take pictures and investigate this further.
     
  17. swingmanu

    swingmanu Member

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    I don't have many pictures from before dismantling (stupid mistake). But here are two pics and one is one I took to remember the cam shaft holders and you can clearly see the slack between camshafts when that "middle plastic chain support" is taken off and the chain tensioner was removed...
    I have the same slack and the same amount of "pins" now when rebuilding.

    Manu

    1655731350685.jpg
    1655731478956.jpg
     
  18. Franz

    Franz Well-Known Member

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    Yes l think so. The chain must be tight from the crankshaft sprocket to the exhaust camshaft sprocket and to the inlet camshafts sprocket. The slack in your photograph between the camshaft sprockets should not be there (correction) it is there because the tensioner is removed.
     
    Last edited: Jun 20, 2022
  19. swingmanu

    swingmanu Member

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    ok, I'm gonna try again, moving the engine to "C" and reinsert the chain tensioner.
     
  20. Franz

    Franz Well-Known Member

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    Yes just follow your manual.
     

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