Technical punto 12 16v cam belt

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Technical punto 12 16v cam belt

shotgun

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punto 12 16v 2000 y reg the cam belt has broken will it damage the engine and how do you set the timing up no marks on cam wheel ???
 
You timing the 16v with the pistons level at mid stroke and the cam locked with the locking tool or something the right size to fit in the slot of the cam, its kinda between 10 and 11mm.

Its pretty well covered in this guide. I do the tensioning bit a bit different but that way will work. I don't mark the top pulley, I lock the cams as described, then take the belt off, make sure the pistons are exactly level, they are often slightly out.. Then slacken off the bolt that holds the cam pulley on the cam, its a floating connection so that pulley will freely turn while the cam is locked in place. Then put the new belt on with the new tensioner, tension the tensioner so the 2 lines on it are inline and tighten it up. Because the cam pulley can spin at this point tightening up the belt is easy, once done you tighten the cam pulley back down. Take the cam locker out and turn engine over several complete cycles and then line up the pistons and check the cam locking slot is inline with the hole i.e. that its still timed up right. Done.

And unfortunately the valver is an interference engine so there is high possibility of other damage if the belt came off when running.
 
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Its pretty well covered in this guide. I do the tensioning bit a bit different but that way will work. I don't mark the top pulley, I lock the cams as described, then take the belt off, make sure the pistons are exactly level, they are often slightly out..

Blu, I can see from going back through a few years of posts that you really know what you are doing, I am wondering though what you mean by the pistons being slightly out with the cams locked. I found with the cam locking tool it was impossible to get a definate locking point that was unquestionably the position where the cam was correct. The locking tabs just did not have sufficiently exact tolerance and yet were really difficult to fit without a great deal of going back and forth with the crank. How can you know which is the exact place?

Mind you thinking about it later I only ever fitted the one locking tool.
 
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yep, i've only ever bothered using the front locking tab, using both seems overkill to me, the inlet cam is turned but some gears that mesh with the exhaust one, which the belt pulley is connected to, so the inlet cam cannot move if the exhaust cam is locked.

The locking tools are a super tight fit, first time i used mine i was convinced it didnt fit the slot in the cam but they do, you must be off ever so slightly for it to not go in. Clearly you dont want to use too much force but try really gently tapping it in with a very small hammer and gently giggle the cam pulley with a socket on if you are struggling. If it really wont go in then you could take a slither off the locker with a file or grinder but you shouldnt have to.... what you describe sounds pretty normal.

What i meant by them often being slightly off is that once you get the cam locked I have found that the pistons aren't bang on level, very close but not bang on. So once the cam is locked and you take the belt off that you may need to turn the crank a tiny amount to get the height indicator things from the kit exactly level. This is the part that the kit is really good for, its very hard to get it exactly level with just 2 long bits of something the same size - with the kit its pretty easy.

so lock the cam, remove belt, double check the pistons are exactly level and adjust as necessary, then fit belt, tension, re-tighten the cam pulley, turn engine over few times to check its all still timed, then put car back together.
 
yep, i've only ever bothered using the front locking tab, using both seems overkill to me, the inlet cam is turned but some gears that mesh with the exhaust one, which the belt pulley is connected to, so the inlet cam cannot move if the exhaust cam is locked.

The locking tools are a super tight fit, first time i used mine i was convinced it didnt fit the slot in the cam but they do, you must be off ever so slightly for it to not go in. Clearly you dont want to use too much force but try really gently tapping it in with a very small hammer and gently giggle the cam pulley with a socket on if you are struggling. If it really wont go in then you could take a slither off the locker with a file or grinder but you shouldnt have to.... what you describe sounds pretty normal.

What i meant by them often being slightly off is that once you get the cam locked I have found that the pistons aren't bang on level, very close but not bang on. So once the cam is locked and you take the belt off that you may need to turn the crank a tiny amount to get the height indicator things from the kit exactly level. This is the part that the kit is really good for, its very hard to get it exactly level with just 2 long bits of something the same size - with the kit its pretty easy.

so lock the cam, remove belt, double check the pistons are exactly level and adjust as necessary, then fit belt, tension, re-tighten the cam pulley, turn engine over few times to check its all still timed, then put car back together.

What i am saying is when the locking tools are fitted but not fully tightened - definately fully in though - after fiddling around to get them lined up via the crankshaft you can still move the cranshaft around a bit in either direction. So since you fiddled to get them lined up how do you know the perfect position?

By the way I found the only way to get these tool in was to put a 10mm allen key in the slot and get it lined up as best I could and then fit the locks without hammering while gently rocking the crank and if it would not work go back to the allen keys and perservere till they went in. no hammering. but the crank still moves slightly once they are in.

So given the available precision via the locking tool it seemed pointless to undo the cam bolt.
 
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its not necessary, its just the way i do it... it makes tightening the belt with nothing moving much easier. clearly the cam won't move cause its locked but if you had the full proper kit from fiat there is a lock for the crank as well, the cheap kits most of us have don't have that part. If you had the full kit you would lock both crank and cams and then put belt on and tension it and unlock the crank and cams and job would be done.

By locking the cam and undoing the cam pulley you can just whack the belt on and tighen the tensioner, the cam pulley will turn with the belt as you tension but the cams themselves don't move, this means you get nice even tension along the whole belt so when the engine spins it doesnt go out of time. I dunno if you have done an 8v fire belt but when you do one of them you have to get the right number of teeth between the cam, waterpump and crank, then the tensioner takes up all the slack on the back side of the belt. If you get that slightly wrong then as the belt turns and the tension equalises along its entire length the timing can do out - hence the turning the engine over several times and rechcking the timing. With the cam pulley spinning freely none of that happens, the belt just tightens all the way along straight away.

As i said, this is just how i do it personally, done alot of them and never had a problem with it not being right first time. And there must be a reason fiat decided to make that pulley floating and not have a woodruff key or something to stop the cam pulley spinning on the cam. And this is the reason in my opinion. But I have used this method on a mk1 punto 16v engine several times, my mums mk2 punto 1.2 sporting and my friends 1.4 16v mk2b sporting - it works perfectly on all of them using the same timing tools.

Lining up the pistons wise, i'm not sure I understand what you mean... that you can turn the crank slightly and it not move the pistons at all?? Thats technically impossible as the pistons are mid stroke - the only thing i can think of is that the height indicators your using are just a tiniest bit short so at the mid point they are just not touching the piston.. Its just a theory but using mine any slight knock on the crank pulley and one or the other pistons come up slightly. You could try take the little o-ring off the the height indicators, the rods should fall thought them then, so screw the tube part in first and then drop the rod down it, or put them in and then pull the o-rings off. Assuming i've undserstood what you are saying that is.
 
Assuming i've undserstood what you are saying.

Its the story of my life that nobody understands what I mean.

I am probably just making a mountain out of a mole hill anyway.

I am supposing however you could probably performance fine tune a 16V engine on a dyno machine for say 3000rpm using an idler wheel to change the belt length on the water pump side much more precisely than the official fiat tools can manage.
 
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i think i understood you.. like i say its not possible for the pistons to not move when they are mid stroke, i can only think that them rods are fully bottomed out and the tiniest gap between them and the piston fully extended. But you are gonna get it close enough if this wiggle you can give is less that a tooth in rotation. ;)
 
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