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 Cam chain tensioner question

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Guzzi Cat
Grignapoco
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PostSubject: Cam chain tensioner question   Sat Feb 20, 2016 1:59 pm

I need a bit of advice from Pete and gang! I have both sides stripped for rollerisation and the sump removed and cleaned.

The problem I have is that I think I may not have put the pin (allen key) to release the tension on cam chain in correctly!
When I look down the chain tunnel I can see that the allen key doesn't seem to be doing anything and the chain tensioner is pushed past it. The camshaft gear is cabletied up and everything looks fine and I turned the engine to TDC on the right side without any problems.
When I was taking off the left side cambox and cam gear I didn't notice any problems but I am wondering if the tension release pin is not in the correct position, will I have a problem when I go to put the new cam on?

Should I now try and put the pin in the correct position (is this through a hole in the plastic chain guide)? Where I have it, is in front of the black plastic guide.
I would have to put a big screwdriver or something through the cam gear and try and leaver the plastic guide back from the chain, but am very nervous of breaking one of the guides. Or should I try and put it back as is?
Any ideas greatly appreciated from people that have done it before.
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pauldaytona
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PostSubject: Re: Cam chain tensioner question   Sat Feb 20, 2016 3:29 pm

To make it clear, you took both sides of at the same time? Man you are making it difficult for yourself, one side at a time, easier to not make mistakes.

You should not move the crank as long as the chain is off.

Left is the difficult side, right is easy.
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Guzzi Cat
Grignapoco
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PostSubject: Re: Cam chain tensioner question   Sat Feb 20, 2016 3:48 pm

pauldaytona wrote:
To make it clear, you took both sides of at the same time? Man you are making it difficult for yourself, one side at a time, easier to not make mistakes.

You should not move the crank as long as the chain is off.

Left is the difficult side, right is easy.
Paul, The chain is not off, it is held to the cam gear on both sides with a cabletie, so the timing should be fine.

I had to send both the old cams, tappets and carriers back to the dealer where I bought the bike because they got me a replacement roller kit from Moto Guzzi.but need the old ones returned first.
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pauldaytona
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PostSubject: Re: Cam chain tensioner question   Sat Feb 20, 2016 4:14 pm

pictures will do normally, thats what they want in Italy. After the swap they want the parts in return.
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Pete Roper
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PostSubject: Re: Cam chain tensioner question   Sat Feb 20, 2016 4:20 pm

What a fucking pain. Over here I just submit photos of damage which are sent to Italy along with a pic of the head to show if it has a 'Dot' in the paint and one of the inside of the rocker cover to show if it's a 'Floating' or 'Non Floating' type. That with pics of the service records is good enough. No need to send parts anywhere apart from to the scrap metal skip out the back of the workshop!

The problem you may have is that if the pin isn't holding the blade back then the tensioner plunger will of expanded and will be almost impossible to compress again because it will be full of oil and you'll have nothing to lever against.

Have you got the heads off? If so yo may be able to remove the guide, push the tensioner blade over to the right and pluck out the tensioner. Once it's out you can bleed it down very easily by simply pushing the ball valve off its seat with a prong and squeezing the oil out. It can then be re-inserted in its well in the barrel wall and the tensioner blade will pull back easily allowing insertion of the pin in its proper location. Having said that I've never had to do that so I've not tried.

If the tensioner plunger can't be removed then you'll need to work out a way to compress the plunger in-situ. This shouldn't be too hard but care has to be taken not to damage the plastic tensioner blade or guide. Replacing the tensioner blade is an engine out job. I found that out the hard way.......

Pete
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Guzzi Cat
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PostSubject: Re: Cam chain tensioner question   Sat Feb 20, 2016 4:44 pm

Thanks Pete, No the heads arent off so I want to try and do it in situ. Will the plunger push back if I take it easy, I could put a piece of timper down the tunnel and try and leaver a big screwdriver to get it back but am also nervous of the guide on the other side of the chain. I presume that if I dont release the tension it would be hard to fit the cam and gear.
I need to get the allenkey in a hole on the black plastic guide, right?


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Pete Roper
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PostSubject: Re: Cam chain tensioner question   Sat Feb 20, 2016 4:54 pm

Why not just whip the head off and be done with it? That way you can pluck the guide plate out. Tell me what thickness head gasket you need and I'll send you one, I've got heaps left over from C and D kits.

Pete
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Guzzi Cat
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PostSubject: Re: Cam chain tensioner question   Sun Feb 21, 2016 1:47 am

Pete Roper wrote:
Why not just whip the head off and be done with it? That way you can pluck the guide plate out. Tell me what thickness head gasket you need and I'll send you one, I've got heaps left over from C and D kits.

Pete
Ye Pete thats what I'll do. I will wait until the roller kit arrives and do the right side first, as that side is already at TDC before I turn her to TDC on the left side. What a fuck that pin insertion turned into (wont make that mistake again)

Hopefully with the head off I will be able to remove the tensioner like you said, I dont want to be hasty and end up having to drop the engine. Thanks for your kind offer on the gasket but I will probaly need an air inlet manifold gasket and maybe an exhaust ring too!
I will see when I take the head off.
Am I correct in thinking, even if I was able to compress the tensioner in situ that there would then be too much tension on the chain?

I am never finished learning! study
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Pete Roper
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PostSubject: Re: Cam chain tensioner question   Sun Feb 21, 2016 2:18 am

The whole point of compressing the tensioner is to give enough slack in the chain so the sprocket can be easily slipped back on to the end of the camshaft. If the pin isn't inserted properly the problem is the tensioner blade, and therefore the tensioner, will extend. This allows oil to be drawn into the tensioner assembly which then hydraulic locks due to the ball valve when the tensioner plunger is attempted to be 'Crushed' again by whatever means. That means there isn't enough slack in the chain to allow the sprocket enough *Height* to slip on to the end of the camshaft.

Once the tensioner is bled down there isn't enough oil in the *Reservoir* it sits in for it to pump up again meaning the only thing that is offering a *Tensioning* function is the weak Spring within the tensioner body which is easily overcome by simply hoicking on the sprocket and slipping it onto the camshaft.

None of this is *Hard*. Yes, I understand it can be daunting as getting the timing wrong can have nasty consequences but it's really as easy as 1-2-3.

Pete
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Guzzi Cat
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PostSubject: Re: Cam chain tensioner question   Sun Feb 21, 2016 3:20 am


Pete[/quote]

[quote "Pete Roper"]This allows oil to be drawn into the tensioner assembly which then hydraulic locks due to the ball valve when the tensioner plunger is attempted to be 'Crushed' again by whatever means.
Pete[/quote]
Cheers for that Pete, I was trying to calculate (badly) that because the tensioner had fully extended and more oil would have entered by the ball valve that trying to compress it with the extra oil that wouldn't be able to escape would put extra tension on the chain and I would be pissing against the wind! Question
Hopefully there is room to get tensioner out to bleed it when head is off.
Thanks for the dig out, greatly appreciated.
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Steve Waller
Carlotto
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PostSubject: Re: Cam chain tensioner question   Sun Feb 21, 2016 4:08 am

Guzzi Cat wrote:
pauldaytona wrote:
To make it clear, you took both sides of at the same time? Man you are making it difficult for yourself, one side at a time, easier to not make mistakes.

You should not move the crank as long as the chain is off.

Left is the difficult side, right is easy.
Paul, The chain is not off, it is held to the cam gear on both sides with a cabletie, so the timing should be fine.

I had to send both the old cams, tappets and carriers back to the dealer where I bought the bike because they got me a replacement roller kit from Moto Guzzi.but need the old ones returned first.

What dealer are you using to sort out the replacement kit? Presumably not one in Ireland since there aren't any?
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Guzzi Cat
Grignapoco
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PostSubject: Re: Cam chain tensioner question   Sun Feb 21, 2016 10:11 am

Steve Waller wrote:


What dealer are you using to sort out the replacement kit?  Presumably not one in Ireland since there aren't any?
The dealer that I bought the bike from in the UK have been great (Forza Italia) and sourced the replacement kits for me. But I had to supply proof that servicing had been carried out and receipts for service items used which luckily I had? I'm glad that I bought the bike from a good dealer who try to help their customers.
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Pete Roper
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PostSubject: Re: Cam chain tensioner question   Sun Feb 21, 2016 12:43 pm

With regards to the pin insertion? Yes, there is a hole in the tensioner blade the pin has to go through and it then goes into a drilling in the other side of the camchain tunnel to hold the blade back.

When I damaged the blade in Mark S's bike the problem was I was using a very large and rigid screwdriver as the pry bar. This caught on the top of the tensioner blade and as I pushed it shattered the blade. Ugh!

Since then I have perfected the method and the two vital things are a long, thin, flexible screwdriver and patience! The blade and chain are clearly visible, (Although hard to photograph.) down the tunnel. The trick is to slip the screwdriver blade between the two and then over a period of some seconds move it downwards in a series of short *Steps*. It is important not to start levering until the screwdriver blade is at the same depth as the plunger otherwise you will be exerting an unusual stress on the frangible tensioner blade. There is also no need to lever with incredible force! The Spring inside the tensioner plunger is very weak, it's there to keep the ball seated and to expand the tensioner barrels but it's the oil inside the barrels that locks and maintains the extension of the tensioner and therefore the tension of the chain. What is needed is consistent application of pressure so the oil in the tensioner plunger can bleed out past the ball and between the close fitting barrels of the tensioner halves.

So, get your long, thin screwdriver between the chain and tensioner blade to the depth of the tensioner plunger and then lever and keep the pressure on. As soon as you relax the plunger will expand again and more oil will be drawn into it and you'll be back to square one. So keep the pressure on and eventually you'll feel the pin slip through the tensioner and into the drilling in the other side of the tunnel. At that point you can withdraw the screwdriver and will feel the pin is *Square* in the side of the barrel and will be held rigidly in place by spring pressure of the tensioner plunger.

Pete
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Guzzi Cat
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PostSubject: Re: Cam chain tensioner question   Sun Feb 21, 2016 1:16 pm


Thanks Pete that is exactly what I wanted to find out and describes it perfectly how the oil will bleed past the ball with pressure applied (I wasnt sure). Thanks for taking the time.
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Belfastguzzi
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PostSubject: Re: Cam chain tensioner question   Sun Feb 21, 2016 1:20 pm

Difficult to photo indeed. These are taken with a compact camera on auto.
> A few photos on Flickr
If I fixed a torch or other light and used manual focus, the photos would show more. I had slightly similar situation. I used a nail as the pin. It went through the hole in tensioner blade – I wasn't sure / couldn't remember from last time if there is a hole, but from what I could see today there is – but it didn't go into hole on other side of the chamber. Today I was able to get enough movement to insert the pointed tip of nail into the hole. I think chain is free enough to allow reassembly of camshaft. I was going to post to say that you might be able to work the tensioner blade back enough with big screwdriver, as I did. Meantime Pete has posted and if I understand, he's saying that you should be able to push the blade. It is tough though especially with lack of visibility and much fear of breakage!

There are a few more of these at the location above
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Pete Roper
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PostSubject: Re: Cam chain tensioner question   Mon Feb 22, 2016 2:22 am

Dave, a word of warning. Obviously when you pulled the cambox the tappets were well fucked but looking at your pic the crank is 360 degrees out for *Correct* stripping.

The cam locating peg should be at 6 O'clock, not 12 O'Clock, for the valve lash to be set correctly. Rollerise it like that and the results could be, errr? *Interesting*

Pete
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Guzzi Cat
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PostSubject: SUCCESS !!!!!   Mon Feb 22, 2016 12:01 pm

I thought about my predicament about trying to compress the tensioner back from fully extended and was prepared to take the head off to remove it. But once Pete explained that it could be compressed and that it would bleed the oil past the ball valve (I was afraid that it might be a one way valve that would not let the oil escape) I decided to have a go before removing the head.

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In case some other poor unfortunate makes the same cock up as me, this is how I fixed it. First I measured the depth that the tensioner is down the tunnel by marking my nice and flexible screwdriver with the green tape that you can see in the photo. The reason for this as Pete explained from his past experience is so that I would not leaver on the plastic guide until it was in close proximity to the tensioner (scared shitless of breaking it).

Because I no longer had the cam shaft for support I put a strong screwdriver through the gear and shimmed it into the correct position by putting some cuts of wood at the back of it. I then pushed my long flexible screwdriver with the tape mark GENTLY between the chain and guide until it was roughly down to the same depth as the tensioner. I then levered the guide away from the chain and in doing so compressed the tensioner very slowly (no hurry, it takes a long time to remove and refit the engine).I poked through the pin hole with a small allen key until EUREKA in she went, happy, happy, joy,joy cheers cheers cheers

The main lesson I learned is don't panic and get ham fisted with the screwdriver, stop study the situation and get all the advice that you can from people with experience. A big tanks to Pete especially for describing the correct procedure to me and to Paul and Belfastguzzi.
So if this happens to someone else don't panic it can be resolved.Thumbs Up
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Belfastguzzi
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PostSubject: Re: Cam chain tensioner question   Tue Feb 23, 2016 8:26 am

Well done: that's good to read, Guzzi Cat. I shall have another go myself, to get the pin (nail) fully in. Maybe I'l make a better pin or use an Allen key. At the time I was doing it, it looked like there wasn't enough room to manipulate an Allen key in there. Hmmm: I should have looked for a shorter key! Now I have the tank off and there's a bit more room/visibility.

Pete Roper wrote:
Dave, a word of warning. Obviously when you pulled the cambox the tappets were well fucked but looking at your pic the crank is 360 degrees out for *Correct* stripping. The cam locating peg should be at 6 O'clock, not 12 O'Clock, for the valve lash to be set correctly. Rollerise it like that and the results could be, errr? *Interesting* Pete

Thanks Pete! I don't know what happened there! I thought I was at the correct TDC position when checking the tappet gaps before disassembly. (Must have been.) But as I was looking at both sides, maybe I turned the crank to check the right side after the left. I have since noticed that Paul warns against doing this (in this topic or somewhere else). I have not disturbed/taken the cambox out of the right side yet though.

But whatever, I have moved the crank somehow. It's just moved a bit (??) as it is the L that should be at 6 o'clock. Is the simple thing now, to get the left side back to correct position, just to keep tension on the chain/gear so that the chain/teeth position remains the same, while turning the crank to bring the L round by 45º to be at the bottom? I will need to be sure that the left side is at TDC in the combustion phase.

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Belfastguzzi
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PostSubject: Re: Cam chain tensioner question   Wed Feb 24, 2016 2:05 am

Actually I think I know now why it is out of position. It moved when I was removing the camshaft/gear bolt, when the crank has to be held to lock the cam. I then forgot about it.
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Belfastguzzi
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PostSubject: Re: Cam chain tensioner question   Sun Mar 06, 2016 4:46 am

Pete Roper wrote:
Dave, a word of warning. Obviously when you pulled the cambox the tappets were well fucked but looking at your pic the crank is out for *Correct* stripping.

The cam locating peg should be at 6 O'clock, not 12 O'Clock, for the valve lash to be set correctly.

Pete

Hi Pete , just btw:
as in above post, crank had turned a bit when I was positioning socket on crank to hold and undo the cam end-bolt. Just one of the by-products of working in a cramped narrow shed workspace where I can't easily get at things. I turned it back to TDC and all is well. Again, thanks for 'eagle'-eyes! Smile
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