Why is my chair tensioner not tensioning ?

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?

 

Is the tensioner like this?

https://xjbikes.com/forums/threads/tensioning-cam-chain.101835/

 

This is the 650. Can you see it moving the guide with the cam cover off?

https://xjbikes.com/forums/threads/cam-chain-tensioner.113558/

 

guide could be to worn to tighten chain
plunger may not be pushing out due to a burr on the rod

 

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.

 

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.

 

Nope don't see it moving the guide

 

I'm considering getting an automatic one https://www.ebay.de/itm/394081137858?hash=item5bc110f4c2:g:1JEAAOSwH3piheky

 

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.

 

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.



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?

 

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

 

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.

 

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

 

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?

 

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.

 

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.

 

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

 

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.

 

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

 

Yes just follow your manual.

 

Yes, that's what I'm doing but somehow it doesn't always make sense to me Thanks for the help !!

 

Let us know how it goes so we can advise you more.

 

Ok updates !

I removed the chain tensioner and repeated the whole operation like the manual. Rotated to C mark and released the plunger of the belt tensioner. Hears it go in position but here is the issue.
When I rotate the engine everything is perfect until right before the T mark and the chain tension loses and it becomes loose on top. I included pictures. '
So I removed the tensioner once more, rotated the engine to C mark and checked through the hole the chain guide. I can push it with my finger and it moves a little bit but it's very small. I'd say the chain tensioner is barely pushing. So my question is... Could there be something preventing the chain guide to move freely and put tension on the chain? Otherwise all the marks are aligned and it's all good...

Pictures are first when the chain is under tension, then when the chain loses tension and then a picture of the exact position on the timing and then a picture of the chain guide

 

Looking at the guide through the opening it is not centred. The bolt and locknut that secures the guide you should reset that. I know you did not disturb it but try it to see if that corrects the problem. Turning the engine anticlockwise you should not be getting any slack in the chain. The inlet cam guide is not moving freely and the slack is happening because the camshaft is getting rotated by valve spring pressure.

 

good point and good eye ! I have to now find that bolt when I head back to the garage. maybe can also try to move in centred with fingers. I didn't disturb it but its true the guide isn't moving freely

Thanks

 

It's not your tensioner it's the guide l am sure of that. Good you put that photograph on that is the problem. Also the face of the guide that the chain runs on has a slightly raised section in the middle that sits between the links along the length of the chain. Make sure it is centred at the top under the cam cover.

 

Reset this and you should be able to centre the guide.

 

Ok I don't find that info in the Haynes. Do you a wider picture on the procedure? Am I supposed to loosen it wiggle the guide and tighten it again?
Manu

 

Slacken the locknut A. Then slacken the bolt B half a turn and then tighten it just till you get resistance because it has then hit the cam chain guide. Then slacken B a quarter of a turn. Keep it there and tighten locknut A. Yes try and square the guide during the process.

 

A a burr is a sliver of metal that could have been taken off the tensioner rod by the bolt. You would be able to feel it with your finger. Or with the cam chain tensioner out the rod won't pull out of the housing after you release the bolt.

 

The tensioner rod goes out when I release the bolt. So it seems it has to do with the guide

 

Yes the guide is not sitting square. Can you take a picture from the top of the engine where the guide is in relation to the chain, if you have enough clearance?

 

I will try, it's tight but will do. I'm gonna do the manipulation you suggested.

 

Yes I hope that fixes the problem.

 

Ok I seem to have fixed it but couldn't do the technique you mentioned. I inserted the tensioner loose so with the spring fully extended and I suspect the rubber part of the tensioner positioned itself better and now I don't have chain slack when turning the engine.

So I guess it's fixed. Thanks for the help

 

To further describe the issue I think the tensioner rubber had pressed so long against the guide that it had created a "groove" so when I reinserted it loose it was able to centre itself back on the guide it seems.

 

The guide will be centred now. Have you started the engine?

 

Im far from starting the engine unfortunately… still waiting on one throttle shaft seal and i need to change valve shims as i redid the valve surface a little

 

Oh that's right I remember now. Should run well with all the work you have done.

 

I hope thanks, i realised just now though that i might not have placed the valve springs in the right orientation…
Im wondering if i should reopen it all,…

 

So did you have the valves out to lap them or do you mean you put the buckets the shims sit in in the wrong places.

 

I replaced everything in its right place but I replaced the valves seals and i didn't specifically paid attention to the orientation of the valves springs when reinstalling the valves in place. I read later in manual they have an orientation... I suspect this is primarily for oscillation issues in the long run

 

Yes better to check them if the manual states that.

 

If I reopen, can I reuse that head gasket? I already closed the head and tightened the bolts to the right torque

 

My understanding is that it can be used because the engine has not been started but l have not tried it so l cannot be sure.

 

Has anyone reused a head gasket when the head was torqued down but the engine was not started?

 

I believe it seals when crushed so I don't think it can be reused.

I'll leave and see what happens.

 

Ok so one of the camshaft bolt is stripped... Maybe precious owner but it doesn't hold torque and spins...
I'm hopeless. Willing to let the bike go to anybody for any price at this point. It's in Helsinki

 

This is for a stripped cam cover thread and l am not an engineer but your camshaft bolt thread in the head can be repaired.

https://xjbikes.com/forums/threads/valve-cover-bolt-hole-stripped.32070/

Here is the thread for the cam cover thread. Yours should be repairable with a hellicoil insert which a machine shop can do. Some of the people who have done this might chime in.

 

Yes I understand the procedure... Unfortunately I don't know if the bike is worth the trouble. I've never done it and can't afford 300-400eu for the job to be done somewhere...
That's areal bummer. Wonder if red loctite would be enough. The bolt grabs on threads but doesn't torque. It spins at the bottom.

Looks like I'm gonna have to pass this project to someone else. So much work put in thanks to all your help but this will get off budget for me...