Timing chain / Tensioner

My T5’s (Square Barrel 850) engine is getting very rattly , just hit 44k miles

Im going to do the valve clearances over the next few weeks and see if it quietens things a little

What the general life span for a timing chain ( not sure if mine has a tensioner fitted…!)

They will all have a tensioner fitted but the org one is aone you have to adjust manually and is bacically a slide with a block of plastic on it. The aftermarket ones and later bikes have a spring loaded tensioner thet will cover well over 100k miles without adjustment.

You need to take the altenator and timing cover off either way to check which you have and if it needs adjustment.

Thanks GB

I’m assuming I need a special bolt to pull the alternator off instead of a puller?

Timing cover looks like it will come off with the engine in the bike

Timing cover does indeed come off easily.A length of allen key shaft plus a short 8mm bolt will pull the alternator rotor off.The aftermarket tensioners can break up and cause problems, don’t ask how I know. The later Guzzi one is better made, fitted from about 1990.

To get he cover off in the frame, you need to spread the downtubes a bit once you have got the engine bolt out.Standard set up with manual tensioner is good for around 30k miles.Not to bad to do, I have an old gambalunga article about changing it I can send you if you want it.

dont forget a new gasket

Hi Don, that would be a big help!, have you got an electronic copy or are you able to post a copy over?Iain

Thanks for that tip Brian, was looking at the rotor wandering how to get it of!mines a 84/5 so I feel a tensioner upgrade coming on, would a later tensioner bolt on to an older engine ?out of interest do the valves hit the pistions if you do snap a chain? or is there enough clearance

Yes it will.
the special tool to remove the alternator is available from Motomecca or instructions on how to make your own about a year ago in Gambo.
I DO NOT recomend the allan key shaft and short 8mm bolt but each to his own.

The special tool is the best, it’s just a 80x8mm high tensile bolt with the first 40mm of thread removed, bringing the shaft down to 6mm.Under no circumstances use a length of mild steel as a spacer, it will bend and you will never be able to remove the rotor again, nor bolt it up again.This is why I recommend a length (about 40mm) of 5mm allan key, as it is very hard, and won’t bend and jam in there.

It wasn’t the bending I had trouble with.
It stayed in place due to magnetism and the slip rings are quite fragile so I couldnt use too much force (shaking) to remove it.
Took me 30 minutes in the end with a set of fine dental tweasers from my time in the green.
Coughing up a Pavaroti was no problem after that.
And anybody is free to borrowmine. It was used at this years V Twin.

Have bolts and lathe here so can soon turn down the end of suitable bolt.I dont fancy having to pluck bits of mild steal our with tweasers

You may find you have many new friends.

You use a hardened steel “tool” as described, Undo the bolt in the centre of the rotor
take out the 4 stator bolts
Pop tool into the hole left by centre bolt (this is why it MUST be the correct length and be hardeded steel) then you pop in the rotor bolt and tighten it up as it tightens it pops the altenator out.

You do have to take out the front engine bolt and to undo the altenator you will need to lock off the engine I tend to pop it into 1st and chock the rear wheel.

If you replace the timing tensioner you will need a special tool to undo the timing chain nut. make sure you get the engine to TDC on the RH cyl and I use tippex to mark the timing chain and nuts.

That’s what I found, they tend to grip the bottom flange a bit tight.

I’m going to throw a cat in among the pigeons here

I have studied this gizmo for some time and come to the conclusion that the rubber block gadget is not a ‘tensioner’, it’s a ‘guide’.

Haynes manual says rotate the chain fully (at least 2 crankshaft revolutions) to find the tight spot in the vertical run (if there is one), and set the block to that. It indicates that it’s pushed across like finger tight only, then you nip up the bolts there.

Mustn’t be too tight else chain will just chew lumps out of the block (or if you didn’t set it on the tightest section of the chain).

MG workshop manual doesn’t mention a dicky-bird about it at all.

You are supposed to check the chain slack at periodic intervals, every 9,000m or somesuch? Every fifth engine oil filter change? Something like that. (I can imagine dealers and home mechanics of the past not wanting to do that, so it’s never done.)

If the block won’t go over any further to take the slack out, presumably this means a new chain is required. (?)

I received a 1990+ version ‘tensioner’ with the sprockets set I got from Reboot, I thought great, until I saw it, not overly impressed TBH, it’s a weedy little plastic slipper shoe with like a weedy little clock spring behind it. Can’t see that holding a chain in place in a month of Sundays.

Everybody wants a ‘fit-and-forget’ solution, but not sure there is one, really.

I’ll get me coat

Surely your description above is describing a tensioner.
The one I had fitted 3 years ago looks up to the job and was bought from Motomecca.
Unfortunatly the MK111 hasn’t turned a wheel since due to the lil’Breva being so much fun.

Well the spring tensioner on my V1000 covered over 100,000 miles without needing any adjustment at all, then I replaced the chain and tensioner as I really felt it had done a job BUT I was told it was all OK and would have lasted some time after. THE org Guzzi one had the timing 10 degree lash when it was swapped out by Paul (Now of Corsa) and the bike had done 55,000 miles

So hey it works well mind you the org is OK but as you say it is NOT checked every 9-10k miles I bet, the one that caused problems I reckon had never been looked at and I hadn’t done so in the 10k miles I had done on the bike to that point.

This is what happens if you try using a cut down 99p screwdriver to pop the rotor off.Took about 3 hours to get the bugger out.Standard manual tensioner:-and new auto tensioner:-When I changed mine, the bike had done 25K miles and it was already starting to eat into the crankcase so it is well worth doing.You will also need new tab washers etc (and castellated nut if you undo the old one with a hammer & screwdriver as I did).

That type of spring tensioner,made by Stucci or Valtech can give problems. The one fitted to my SPIII had a broken spring, bits of it lying in the bottom of the timing chest. Fortunately none got tangled up in the chain. I have heard of others doing this too.I refitted the original late Guzzi spring tensioner which is far better made. Why on earth the previous owner swapped it in the first place I will never know.

OK maybe it’s a matter of interpretation, to me, a tensioner is a spring loaded or hydraulically activated thing. To me, the rubber block thingy is merely intended to prevent the chain flapping about too much. It doesn’t actively move or anything. It ain’t a perfect design by any means, and I imagine dates well back into the 1960’s