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Discussion Starter #1
Doing 156 1.8 TS cambelt struggling to centralise cambelt tried everything I think slackening tensioner pushing belt over to near side before re tensioning centralising before tensioning but it’s working it’s way towards the offside and I don’t know why??

Worried that when engine is running belt is going to work it’s way off....

Idler bolt was stripped so that was retapped and vcoil threaded square to crankcase to make sure of that I dismantled an old one and screwed just the bolt and backplate in to make sure it was flush so I don’t think it’s because the idler is incorrectly guiding the belt anyway belt looks in good central position on idler.

Totally lost on this one be grateful for any advice please
Also tensioning belt using T tool is proving hard if it’s set so the pointer is at the hole before the engine is rotated then pointer drops to below hole after turning engine or if it’s set so pointer is above hole won’t seem to align with hole after engine is turned??

Cheers
 

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First off turn engine manually many times to see where the belt will naturally sit on all the pulleys. It should do so after just a few turns. It is completely normal for the belt to move relative to how it was fitted. As long as the belt doesn't overhang any of the pulleys, it is fine. If in doubt, fit the covers securely before running the engine. That will be enough to hold the belt on without coming off. The rubbing sound will alert you to the fact the belt is trying to move forward on the pulleys.

I've see a few engines with partly displaced belts due to pulley misalignment. Just because it is a bit forward, doesn't mean it is in danger of coming right off. That would entail serious pulley misalignment.

From what the pictures show, that is nothing to be concerned about as long as it is no worse on the coolant pump, tensioner or idler. As you have obviously tightened up the idler bolt, I think the threads are good and the alignment is also ok.

If the belt is further off any of the other pulleys, post these pictures but if that is the worst bit of the belt's natural running position, it will be okay.

With regard to the tensioner pointer, remember this is a dynamic tensioner which moves around loads (vibrates) when the engine is running. As long as the pointer is at the hole when the cylinders 1&4 are at top dead centre, the belt tension is correctly set.
 

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Discussion Starter #3
First off turn engine manually many times to see where the belt will naturally sit on all the pulleys. It should do so after just a few turns. It is completely normal for the belt to move relative to how it was fitted. As long as the belt doesn't overhang any of the pulleys, it is fine. If in doubt, fit the covers securely before running the engine. That will be enough to hold the belt on without coming off. The rubbing sound will alert you to the fact the belt is trying to move forward on the pulleys.

I've see a few engines with partly displaced belts due to pulley misalignment. Just because it is a bit forward, doesn't mean it is in danger of coming right off. That would entail serious pulley misalignment.

From what the pictures show, that is nothing to be concerned about as long as it is no worse on the coolant pump, tensioner or idler. As you have obviously tightened up the idler bolt, I think the threads are good and the alignment is also ok.

If the belt is further off any of the other pulleys, post these pictures but if that is the worst bit of the belt's natural running position, it will be okay.

With regard to the tensioner pointer, remember this is a dynamic tensioner which moves around loads (vibrates) when the engine is running. As long as the pointer is at the hole when the cylinders 1&4 are at top dead centre, the belt tension is correctly set.
Thanks that’s helpful I’ll take a closer look in the morning at the other pulleys I’ve made several attempts to push the belt in towards the engine more with the belt untensioned but it’s hard to shift it much. As regards the tensioner I’ve got the locks fitting perfectly with TDC on number 1 using the DTI, but the pointer just doesn’t seem to want to stay over the hole I aimed to get it pointing centrally at it as if across the diameter, however it falls below that on turning the engine over, or is elevated above it. I’ve made innumerable attempts to get it right I’m beginning to wonder if the tensioner is faulty....but it’s probably my fault!
 

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Did you tweak crank slightly clockwise when fitting the locks as that would put the slack to back of belt causing tensioner to drop below the mark?

I wouldn’t worry about that Belt being over slightly it will find its position ok once running. Seem to recall when I had a 1.8 twinny many moons ago I ran it with cover off for a bit to check it centralised and tensioner pointer was correct before putting it back together fully
 

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Discussion Starter #5
Did you tweak crank slightly clockwise when fitting the locks as that would put the slack to back of belt causing tensioner to drop below the mark?

I wouldn’t worry about that Belt being over slightly it will find its position ok once running. Seem to recall when I had a 1.8 twinny many moons ago I ran it with cover off for a bit to check it centralised and tensioner pointer was correct before putting it back together fully
Thanks I tried to stop the crank moving by putting a socket on it attached to a breaker bar then clamping that to the brake caliper. I did notice that while trying to tension the belt as soon as tension was taken off the needle on the gauge was dropping which I assumed was due to small reversible movement at the crank. I’m using the peg tool to tension the belt, but if I turn it so pointer is on the reference hole as soon as I tighten the nut the pointer rises above the hole. I’ve tried setting it below the hole to allow for the apparent extra tension that’s going on when the nut is done up, but it’s totally random and I think there’s something wrong with what Im doing. Surely it shouldn’t be as hard as this?
 

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Discussion Starter #6
Thanks I tried to stop the crank moving by putting a socket on it attached to a breaker bar then clamping that to the brake caliper. I did notice that while trying to tension the belt as soon as tension was taken off the needle on the gauge was dropping which I assumed was due to small reversible movement at the crank. I’m using the peg tool to tension the belt, but if I turn it so pointer is on the reference hole as soon as I tighten the nut the pointer rises above the hole. I’ve tried setting it below the hole to allow for the apparent extra tension that’s going on when the nut is done up, but it’s totally random and I think there’s something wrong with what Im doing. Surely it shouldn’t be as hard as this?
Just a thought in the instructions it says to thread the belt over the water pump last. I couldn’t get it on that way so I ended up stretching round the exhaust sprocket which was really tight. Just wondering if the way of getting it on affects it’s podition tension etc? Though not sure why it would
 

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No matter how/where the belt is fitted, it always moves to its natural run position after a few (2 or 3) cycles (camshaft revolutions). Don't worry if you fit lt onto the coolant pump or exhaust camshaft pulley last. The tensioner pointer will only go to the prescribed position at TDC. If after a couple of turns, the tensioner pointer seems so incorrect that it must be adjusted, then adjust it. For the 2.0, I usually err on the tight side. The 1.6 has a different tensioner which has a stronger spring. If anything, I let that go slightly slacker.
 

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Discussion Starter #8
Just a thought in the instructions it says to thread the belt over the water pump last. I couldn’t get it on that way so I ended up stretching round the exhaust sprocket which was really tight. Just wondering if the way of getting it on affects it’s podition tension etc? Though not sure why it would
No matter how/where the belt is fitted, it always moves to its natural run position after a few (2 or 3) cycles (camshaft revolutions). Don't worry if you fit lt onto the coolant pump or exhaust camshaft pulley last. The tensioner pointer will only go to the prescribed position at TDC. If after a couple of turns, the tensioner pointer seems so incorrect that it must be adjusted, then adjust it. For the 2.0, I usually err on the tight side. The 1.6 has a different tensioner which has a stronger spring. If anything, I let that go slightly slacker.
Thanks for that I’ve readjusted the tensioner and now at TDC the pointer is just below the diameter of the hole when I’m rotating the engine the pointer is oscillating between positions of well below the hole and well above is that what it should do? This is the 1.8 do you reckon it would be best to set the pointer so the belts a bit tighter? Thanks again for your kind advice
 

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Discussion Starter #9
Thanks for that I’ve readjusted the tensioner and now at TDC the pointer is just below the diameter of the hole when I’m rotating the engine the pointer is oscillating between positions of well below the hole and well above is that what it should do? This is the 1.8 do you reckon it would be best to set the pointer so the belts a bit tighter? Thanks again for your kind advice
This is where the pointer is at TDC
 

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Discussion Starter #11
I’ve adjusted the tensioner but I’m worried about the decentralisation of the belt in particular at the crank the belt edge is right against the rim of the crank sprocket so even if it doesn’t come off it’s goong to wear the belt edge this can’t be right I guess the idler must be misaligned but the backplate of the old one screwed flush against the crankcase so it’s s puzzle I attach some pictures would be grateful for your further help chaps maybe it’s heafing for the scrapyard!
 

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Have you run the engine to see if it finds its position?
I did a golf 1.8 turbo belt today that stayed where it was spinning by hand but once running it found its position fine
 

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It will run over away from sprocket once engine is running at 800rpm. Just make sure it is all in time and get it in a position to run for a short time even if it’s with alternator belt off. It will find its position and you can see a true tension reading on the pointer
 

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Discussion Starter #16
Have you run the engine to see if it finds its position?
I did a golf 1.8 turbo belt today that stayed where it was spinning by hand but once running it found its position fine
No not yet just worried it’s going to come off really struggled to set the pointer got it so at tdc it’s slightly above the centre best I can do when I took old belt off that was definitely in the middle of the cam sprockets I’ve turned the engine over loads of times as Fruity recommended so I’ll have to put the rocket cover back on hope for the best and fire it up
 

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Discussion Starter #17
Ok thanks it’s certainly timed with the locks I’ve checked that many times and at tdc they’re going on perfectly that tensioner needle is buggar if you look at it after adjusting it under the wing it can appear too high ie above the hole but when I photoed it with the camera facing it seemed ok just a tad above the hole centre
 

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It won’t come off as the crank sprocket keeps it on. The pointer should be on the mark when idling it will tighten slightly as it warms up. When engine stops it can go either above or below mark depending where slack sits after stopping. So long as it’s on the mark when cold and idling I would box it up
 
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