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cambelt jumped a tooth.

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Old Feb 21st, 2010, 00:56   #21
grass hopper
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Caution here mate, just because the cam pulley marks are out dose not mean the timing is incorrect. When we replace timing belts we use the rear cam locking tool to time the cams correctly and lock the crank with a dedicated pin.

The cam pully is attached to the cams by 3 bolts, the puley holes are elongated which alows the cam puleys to move. This is so during setting the tensioner the load is distributed on the full run of the belt.

To confirm cam and crank correct sequensing an oscilloscope is used to vew cam and crank corilation. Also your compressions do not indicate incorrect valve timing. A vaccume guage should show around 22 hg at idle confirming correct valve timing.
the volvo standard time is 1 hour to replace the cambelt as per manual, the 3 bolts on the cam pulleys are not loosened on belt replacement so the cam locking tools are not required,they are only required if the head/cams have been removed.
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Old Feb 21st, 2010, 18:19   #22
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So why the elongated bolt holes on cam pulleys?
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Old Feb 22nd, 2010, 18:44   #23
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If you feel confident enough, I would remove the belt (lock it up first) and see if you can get them marks spot on ie turn it back a tooth, once you have done this and retensioned belt, turn over by hand twice and see if all lines up again, sometimes an engine can look a tooth out but when you go to put it back a tooth its miles out meaning it was right in the first place, have you checked the tensioner for play or and idler pulleys if there is any?

As I say if after you have moved it back a tooth and it all lines up better than before after turning it over by hand cranking twice, then i think you would have solved it!
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Old Feb 22nd, 2010, 19:07   #24
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If you feel confident enough, I would remove the belt (lock it up first) and see if you can get them marks spot on ie turn it back a tooth, once you have done this and retensioned belt, turn over by hand twice and see if all lines up again, sometimes an engine can look a tooth out but when you go to put it back a tooth its miles out meaning it was right in the first place, have you checked the tensioner for play or and idler pulleys if there is any?

As I say if after you have moved it back a tooth and it all lines up better than before after turning it over by hand cranking twice, then i think you would have solved it!
what do you need to lock it off???
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Old Feb 22nd, 2010, 20:50   #25
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So why the elongated bolt holes on cam pulleys?
to allow the cams to move on the pulleys slightly if the belt is installed while installing the locking tool.

the locking tools at the crank and cams are required when reinstalling a head or if a front cam seal has been replaced,the cam pulleys are fitted finger tight so they can spin freely on the cams then the belt is tensioned then the 3 bolts are tightened,this only needs carrying out as mentioned or if the front pulley bolts have been loosened and you suspect a cam has moved.

changed about 100 cam-belts over the years on Volvo's and so long as you align the marks (that can be half a tooth out as per photo) and make your own tipex marks then you cant go wrong,the tools aren't required as its been set (valve timing) at the factory.
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Old Feb 22nd, 2010, 21:52   #26
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to allow the cams to move on the pulleys slightly if the belt is installed while installing the locking tool.

the locking tools at the crank and cams are required when reinstalling a head or if a front cam seal has been replaced,the cam pulleys are fitted finger tight so they can spin freely on the cams then the belt is tensioned then the 3 bolts are tightened,this only needs carrying out as mentioned or if the front pulley bolts have been loosened and you suspect a cam has moved.

changed about 100 cam-belts over the years on Volvo's and so long as you align the marks (that can be half a tooth out as per photo) and make your own tipex marks then you cant go wrong,the tools aren't required as its been set (valve timing) at the factory.
so are we saying i can just take the tention off etc and turn it back a notch, that picture ive posted is the crank spot on, the top two are as they are in the picture, rotor arm points to no1 as set in pic, and piston number 1 is at the tdc. anyadvice on best way to do would be great.
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Old Feb 22nd, 2010, 22:05   #27
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So why the elongated bolt holes on cam pulleys?
Right there is absolutely no need to slacken the cam bolts to tension the belt I have dont alot of these timing belts in my time,there are also no specialised tools required.
As for the elongated holes I have seen none on this engine,and when checking the bottom timing mark the crank shaft pulley has to be removed to see the mark behind it.
this information comes from the new autodata cd I have recently recieved so if its wrong then so is every other garage lol

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Old Feb 22nd, 2010, 22:13   #28
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Right there is absolutely no need to slacken the cam bolts to tension the belt I have dont alot of these timing belts in my time,there are also no specialised tools required.
As for the elongated holes I have seen none on this engine,and when checking the bottom timing mark the crank shaft pulley has to be removed to see the mark behind it.
this information comes from the new autodata cd I have recently recieved so if its wrong then so is every other garage lol

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im hoping ive done the crank postion right, in that picture that was posted with the pulley near off you can see the mark if you shine a tourch down from the top of the engine you can see the mark with the pulley still in place if you look at the pulley thing the belt goes round there is a odd one out well thats what it looks like to me im sure it has a small pin like hole on the spline, quote me if im wrong but im new to all of this, and would love the input info etc.(please note i have not touched anything just alined it all up as im trying to find out the cause of the engine what i call running on-and shutting of dead sometimes.) and looking at the top to pulleys the right hand side one inlet i think is out dosnt sit in alinement, (ps volvo mec has told me they should both sit spot on in the middle of the marks on the back case cover.)
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Last edited by lou; Feb 22nd, 2010 at 22:19.
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Old Feb 22nd, 2010, 23:02   #29
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what do you need to lock it off???
You dont need to literally lock this engine, just make some nice clear marks I use tippex it doesnt have to be on the timing marks themselves just mark your own points, as long as they are easy to see, just get your crankshaft at TDC as in your pics, then make the marks onto the pulleys and onto the cover, its just so basically if it moves when removing the belt you can at least put it back where it was, but try and get those original marks to line up better, it may be a long way out after you move it one tooth, that way you will know it was right at first, when I first started doing timing belts, sometimes after I fitted the new belt I would spend ages trying to get the marks spot on but a lot of times it would never be dead on the mark but if i tried a tooth either way it would be obviously out, so i would set it on the tooth i could get the closest to it, dont forget to rotate the crank twice to bring it back to TDC by hand and re-check all the marks, This is very important!
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Old Feb 22nd, 2010, 23:28   #30
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You dont need to literally lock this engine, just make some nice clear marks I use tippex it doesnt have to be on the timing marks themselves just mark your own points, as long as they are easy to see, just get your crankshaft at TDC as in your pics, then make the marks onto the pulleys and onto the cover, its just so basically if it moves when removing the belt you can at least put it back where it was, but try and get those original marks to line up better, it may be a long way out after you move it one tooth, that way you will know it was right at first, when I first started doing timing belts, sometimes after I fitted the new belt I would spend ages trying to get the marks spot on but a lot of times it would never be dead on the mark but if i tried a tooth either way it would be obviously out, so i would set it on the tooth i could get the closest to it, dont forget to rotate the crank twice to bring it back to TDC by hand and re-check all the marks, This is very important!
thankyou very much for your time, can you tell me does the (serpintine belt) need to be removed, b4 i do the other, or do you leave it in place???, if remove how do you do it, or is there a link on that topic.
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