Technical Stilo Abarth Timing Belt Change

[johns]

I had a tensioner failure a few weeks ago on my Stilo Abarth after approx. 65,000 miles, so I thought I'd get all the belts changed. The tensioner got to the end of its tensioning and the belt came away from the crank pulley.

I use a company called Torque Italia in South East London to do all my tuning and maintenance work on my Fiat Coupe 20V Turbo (and it is the 2nd most powerful Fiat Coupe in the UK with 460BHP). The proprietor's name is Barbz (he's pretty much a one man band), and he is extremely well respected in the Fiat Coupe community and indeed the Lancia Delta Integrale community (used to work at Evocars/Barry Waterhouse Engineering)

Anyway, the coupe 20V/turbo engine and the Stilo abarth 20v engine are closely related, so I asked him to do my belt change. He changed all my belts, all my tensioners, fitted an uprated water pump and all the labour for £395, and he'll do anyone else for the same price. Considering what a Fiat main dealer charges I think that's a bargain!! Also considering Fiat don't always change all the ancillaries (esp. the water pump) for a lot more it makes sense to go to a renowned independent fiat specialist for the belt change even if you want to keep your routine servicing with Fiat.
I should point out that there are some subtle but important differences between the coupe and Stilo ancillaries and he was fully familiar with these as well.

So if you're due for a belt change (6 years or 72,000 miles) it's well worth giving him a shout. And if you get a lot of whining like I did before mine went maybe it's worth doing them sooner rather than later. My timing belt was extremely shiny and I think it wouldn't have lasted much longer either. It was a little suprising actually.

This is a shameless plug because he sorted me out of a tight spot by fitting me in instead of a potential 10 day wait at my local Fiat dealer!

 

[alexGS]

I've changed cambelts on many of my previous cars myself - several Unos, couple of Tipos, my Alfa 164... And to think I'm annoyed if I have to spend more than the equivalent of £30... deary-me, the Stilo is going to be horrendously expensive isn't it...

Also I usually look at the tensioner after 100,000+ miles and decide it's OK till the next change... obviously not the case any more!

Reading the eLearn CD, I see FIAT say to unbolt the cam pulleys during the belt change, and re-synchronise later. I'm wondering why this would be necessary... Surely if the belt was replaced with a new one, everything would be back to the same position as it was in the first place?

Anyway, if the job needs doing, it's gotta be done, I guess.
-Alex

 

[Deckchair5]

"Reading the eLearn CD, I see FIAT say to unbolt the cam pulleys during the belt change, and re-synchronise later. I'm wondering why this would be necessary... Surely if the belt was replaced with a new one, everything would be back to the same position as it was in the first place?"

Yes, I thought the same, when changing Bravo timing belts I read and reread the manual and thought "Why would you need or want to loosen and move the cam sprockets on the cams? If the engine was ok when you took the old belt off then, provided everything is in the same place as when you started, it'll be ok when you put the new belts on"

So, after making suitable timing marks on the cam sprockets and crankshaft pulley before taking the old belt off, then I've done Bravo timing belt and tensioner changes, which are identical to the Stilo, without ever needing the alignment tools.

Yes, you'll need the alignment tools if you've shed a belt or fitting a new cylinder head etc as you will be lost as to where everything should be but other than that you can do a straight swop of components.

Fiat use the logic of locking the two camshafts in the correct position, lock the crackshaft in the correct position and then move the cam sprockets to suit the belt, that's why they don't put timing marks on them. Finding crankshaft TDC though isn't the most accurate thing in the world and belts do most of their stretching within the first 1000 miles.

Most manufacturers can't be bothered with that and key the cam sprockets in place to the camshaft, never to be moved again. The Fiat way is very accurate and leaves no room for error but a belt will still stretch over time a really tiny amount,most of it in the first 1000 miles so it's out straight away from the very accurate setting up, but it never stretches enough to be a whole sprocket tooth out

 

[PNL]

Anyone tried this little dodge

Remove all the necessary guards ect as you would when doing the belt change and then while rotating the belt cut it through the centre with a very sharp craft knife as you rotate now you will be left with half a belt around the cam sprockets and tensioner and crank pulley then quietly thread on the new belt along side of the old half and quietly carry on rotating and pushing over the old half and new belt as you are rotating until you are in a position to cut off and remove the old belt and push the new belt completly over

 

[Deckchair5]

True but it's a fool who doesn't change the tensioner with the belt and that'll mean the belt has to come off one way or another

The cringe post is when someone says "I've taken the cam belt off no problem but I can't find any timing marks, can anyone tell me where they are?"

 

[johns]

Both the inlet and exhaust pulleys are vernier so you can adjust the advance or retard of the cams. They are not marked with degrees though.

The reason Fiat talk about resynchronisation is that you have to also bear in mind the variator, because the pulley is floating so to speak on the variator, and therefore if you move the pulley you might move the variator and/or the cam. Putting it back to a position you marked will not necessarily get you back to the right position, because you might just be taking degrees off the variator and the cam might be sitting still, whereas when you moved it the cam may have also moved.

The botch with cutting the belt is pointless because you really want to change both your tensioners and waterpump during the belt job. I fitted an uprated waterpump because I am not a fan of the plastic impleller as I have previously had one fail on me. The uprated water pump has a brass impeller which is stronger.
BTW if you have Colombo & Bariani cams (sometimes referred to as 'Abarth cams' as they used to make cams for the real Abarths) they are timed up using a different mechanism to cam locks.

 

[PNL]

Have you got a link for the uprated water pump the information would be very usefull to us all

 

[johns]

It's just the same as the normal unit but with a brass impellor instead of a plastic impeller. There are situations where the impeller can break on the shaft with the plastic impellers, the brass ones are far stronger.

I got it from the same place that did my belt and it is pretty common to use them on Fiat Coupes, so if you want one call Torque Italia (www.torqueitalia.com) and he will sort one out. Fiat do not sell it, and you probably couldn't ask a Fiat dealer to use one. The uprated unit costs about £40 I think (plus postage I guess), the Fiat one is closer to £50 AFAIK!

Cheers
John

 

[jut1972]

So if you're due for a belt change (6 years or 72,000 miles) it's well worth giving him a shout.

I think its five years or 72,000 which ever is sooner. Though seems to be an endless debate

395 is a great price, I'll be booking that this time next year

 

[alexGS]

The reason Fiat talk about resynchronisation is that you have to also bear in mind the variator, because the pulley is floating so to speak on the variator, and therefore if you move the pulley you might move the variator and/or the cam. Putting it back to a position you marked will not necessarily get you back to the right position, because you might just be taking degrees off the variator and the cam might be sitting still, whereas when you moved it the cam may have also moved.

Interesting. But I take that as a further reason for why the cam pulley should not be taken off; surely if the pulley stays in one place from when the old belt comes off to when the new belt goes on, that is the safest way?

If you do 'take degrees off the variator' by turning the pulley, what actually operates the variator? Does it re-align itself when the engine is started up?

-Alex

 

[johns]

Yes - in an ideal world you would lock the cam to the pulley when you do the belt change so they cannot move relative to one another via the travel in the variator. But there is no tool to do that. There are just cam locks (and of course your gauge for measuring TDC).

The variator is actually at its most advanced position when the variator solenoid is inactive. When it is active (most of the time in normal driving) then the cam is retarded to give better torque. So in changing a belt the movement of the pulley in one direction will yield a movement of the cam alone, but in the other direction it will always yield a movement of the variator (i.e. the floating I mentioned), and whether the cam moves/how much it moves by is indeterminable unless it is locked with the locking caps.

If you are confident you can do the belt change with absolutely no movement on the inlet pulley then you don't even need any special tools (aside from a RIBE bit set to take the belt cover off and the aux pulley to get to the crank/main pulley), as you could mark the crank/main pulley and exhaust pulley. I have changed my fair share of belts in the past, including some twice as complicated (think a V6 with two balancer shafts) and I wouldn't be confident not the move the inlet pulley at all.

BTW The balancer shaft is driven by the oil pump via a chain inside the block (with the oil pump being driven by the crank directly) so it does actually make the belt change easier than a lot of engines

I would never touch the vernier adjustment unless I was tuning via the cams (which is possible even on a stock Stilo Abarth and you might get a couple of BHP added for a little loss in low-down torque).

 

[Athos]

I would never touch the vernier adjustment unless I was tuning via the cams (which is possible even on a stock Stilo Abarth and you might get a couple of BHP added for a little loss in low-down torque).

What hapens if you slightly advance the cams?

 

[johns]

well I'm not sure you'd want to advance both, you may want to retard the exhaust cam if you're playing with cam timings. In general if you advance the inlet cam it makes the car more peaky, you lose a little low down torque for a little top-end. Fiat will have chosen the happiest compromise in order to get a flat torque curve.
The 2.4 engine is 'undertuned' if you like, and you could easily make a lot more power out of it. It might have something to do with the history - the engine was first available not in the Stilo, but in the Lancia Kappa Coupe 2.4 in 1998. The Kappa's 2.4 has a different crank, and slightly different head, but aside from that Fiat made very few changes to the engine. The Kappa 2.4 had to fit into a range with a glut of other engines and so it had to make a specific target power which was well below the 2.0 20V Turbo Kappa Coupe engine. In reality I think you could easily get the Abarth 2.4 engine to make a lot more power if you know what you're doing (and I don't mean bolt on a ridiculous exhaust and airfilter that is not compatible with the VIS system)

 

[Athos]

well I'm not sure you'd want to advance both, you may want to retard the exhaust cam if you're playing with cam timings. In general if you advance the inlet cam it makes the car more peaky, you lose a little low down torque for a little top-end. Fiat will have chosen the happiest compromise in order to get a flat torque curve.
The 2.4 engine is 'undertuned' if you like, and you could easily make a lot more power out of it...

As the 2.4 has plenty of torque I assume it will not harm to lose some in order to gain more BHP, correct?

 

[Athos]

(and I don't mean bolt on a ridiculous exhaust and airfilter that is not compatible with the VIS system)

But a decat (2nd cat) straigh exhaust pipe will always help engine, true?

 

[johns]

well yes and no, it will not help the low down torque as the restriction is a good thing low down.