Technical Fiat 500 new cambelt and spark plugs

[vexorg]

Looks like a simple enough job, probably could do it without the locking kit for a single cam car.

 

[chris3234]

Looks like a simple enough job, probably could do it without the locking kit for a single cam car.

No doing without the locking kit often cause the phonic wheel/phantom misfire issues so it's really recommend you use one

 

[PZ500]

Spark plugs for £140, that sounds crazy. I just bought 4 plugs for aud $40 and swapped them myself in 45 minutes (did air filter at the same time).

 

[vexorg]

No doing without the locking kit often cause the phonic wheel/phantom misfire issuesw

The link above doesn't show the cam pulley, does that not have a timng mark for alignment?


I had to use a locking pin on my citroen a few weeks ago, only because the cam pulley has no marks.

Mornern cars are so poorly designed, I've done timing belts on many cars over the years and the only ones that really needed the locking kit was the v6 engines (since 4 cam pulleys).

 

[chris3234]

The link above doesn't show the cam pulley, does that not have a timng mark for alignment?


I had to use a locking pin on my citroen a few weeks ago, only because the cam pulley has no marks.

Mornern cars are so poorly designed, I've done timing belts on many cars over the years and the only ones that really needed the locking kit was the v6 engines (since 4 cam pulleys).

There are no timing marks on the engine's as they don't have keyed camshafts

 

[Pugglt Auld Jock]

Chris, What I'm about to post here is in no way intended to antagonize you, it's just what I've done and subsequently found out as a result of doing these belts by the "tippex" method.

Vexorg, You may enjoy reading these two posts I made when I experimented with the possibility of doing this job without using timing tools (I did have the tool kit but I used it to double check that the "tippex" method resulted in a satisfactory outcome, not to actually set up the engine. Also you have to be sure that the cam pulley on these "unkeyed" engines has been correctly timed the last time the job was done - If someone before you tightened up the cam pulley in the "wrong" place then it'll still be wrong after you've finished if you use the tippex method. So I believe if it's the engine's first belt change then it's likely the factory will have set up the engine correctly isn't it? however if it's an old or high mileage engine which may have been "fiddled" with by someone else then you really need the timing tools to check everything is correctly aligned.

Here's the links to my two posts:

https://www.fiatforum.com/panda/459903-beckys-timing-belt-ongoing-saga.html?459903=#post4338582

https://www.fiatforum.com/panda/460629-timing-belts-again-becky-her-pal.html?460629=#post4344018

Our Panda engine has a solid cam sprocket and the Punto has a VVT sprocket, not that that makes any difference unless you are slackening the cam sprocket retaining bolt. The crank sprocket is keyed to the crankshaft so it can't change it's angular relationship to the crankshaft but the cam sprocket is unkeyed so as soon as you slacken it's retaining bolt you definitely will need the timing tools to set it up again. I believe the cam belts, whether it be a Gates (my favourite) Dayco, genuine Fiat, SKF, Continental, etc are all so accurately manufactured that any dimensional difference between them is infinitesimally small and can be discounted. So the only variable factor is whether that cam sprocket bolt was tightened up with the sprocket/camshaft "interface" correctly set up. Of course unless you really know what you are doing and feel very confident about "winging it" I would suggest you buy the timing tools and do it as recommended. Interesting though that the PMM (Professional Motor Mechanic) magazine, in this guide: https://pmmonline.co.uk/technical/how-replace-timing-belt-fiat-500/ (which I think is from Continental - a major belt manufacturer) makes no mention of slackening the cam sprocket pulley?

At the end of the day we all have to make our minds up as to what advice we are going to take and live with the outcome but I feel very confident now doing these belts without slackening the cam sprocket bolt - with the caveat that I'd always check the timing on an engine I don't regularly work on by installing the timing tools when I'd finished before I went anywhere near starting it up.

PS. 3+ years down the line now for both the Punto and Panda and neither has flashed up it's check engine light. Both running very well with no indication that a Phonic Wheel Relearn is required.

 

[vexorg]

That was kind of my thinking, you can only be out by a whole tooth and that should be obvious. If it runs fine now then there's not reason for it to run any different after.

I'm pretty sure they over complicate things to force you to go to a dealer.
Who in their right mind thought it was good idea not to have a locking pin on the cam pulley.


Although, thinking back, we had a fiat tipo years ago, that's the only car I've had where the timing marks were wrong. Ran like a dog when it was timed corrrectly, one tooth back and it was fine. So maybe fiat markings aren't so good anyway.

Anyway, the 500 1.2 engine looks simple enough to do.

 

[jrkitching]

That was kind of my thinking, you can only be out by a whole tooth and that should be obvious

Who in their right mind thought it was good idea not to have a locking pin on the cam pulley.

The whole point of using an unkeyed cam sprocket is that the timing is infinitely variable, so you can adjust it precisely to take account of any individual variation in parts tolerances. So it makes no sense on these engines to talk about it being a tooth out; it can be set anywhere you want.

Engines with keyed sprockets can only be set to the nearest tooth (and yes, I've had cases on such engines where the marks fit almost exactly halfway between two teeth :bang.

Is the Fiat system better? You can set the valve timing with absolute precision (with the correct tools), but it makes the process a lot more complicated than on engines with keyed sprockets.

It's certainly possible (though not recommended) to do it without the tools, but there have been countless posts here from folks who've done it without, and then had problems with rough running.

 

[vexorg]

The whole point of using an unkeyed cam sprocket is that the timing is infinitely variable

And the whole point of a keyed pulley is that is doesn't change. Fixed once and stays put. I've seen engines where the cam pulley has slipped, even keyed the pulley should be torqued pretty high.

It's not like we are talking about fine tuning a high performance engine, it's a 1.2 8v runabout engine. Almost every other engine I've changed the belt on with keyed cam has been far higher performance and never suffered due to needing "infinite" adjustment.


But having seen some of fiat's other poor design abilities on the car, I'm not really that surprised.

 

[Pugglt Auld Jock]

Good Morning jrk, vexorg, chris and anyone else whose's finding this thread as interesting as I am.

It's been a number of years since I last stripped and rebuilt an engine entirely and even longer since I built one up where performance was the main consideration. However I have built a number of engines, from small 2 strokes - which are very interesting subjects to extract increased power from - to small 4 strokes - mostly Minis, but I was also involved in a couple of VW Beetle engines going into beach buggies. All these engines (not the 2 strokes of course) had keyed sprockets on both crank and cam shafts. Very accurate valve timing is a critical factor if the full potential of a performance cam is to be realized so you get into things like offset woodruff keys and, at greater expense, vernier adjustable sprockets. Interestingly, perhaps? I had to revisit a couple of the Mini engines which were seeing use in fast road/hillclimb and sprint and decided to change one from a single row timing chain (this was actually the first engine I ever built for extended performance and, in my inexperience, I didn't change the timing chain to the Cooper "S" Duplex type) The other one we just decide to put a new chain on as "insurance". In both cases the new chain and sprockets - always new sprockets with a new chain no matter how good the old sprockets look visually. No matter how good a used sprocket looks there will be wear there which will cause the new chain to wear more quickly - just ask anyone who runs motor cycles, except perhaps a Harley or shaft drive enthusiast? What I found was that when I dropped the new sprockets and chains on using the previously fitted offset keys, the timing "dialled in" exactly the same so I didn't need to use different offsets on the keys.

However we are here considering toothed belt driven assemblies so let's get back to that. This same timing effect is what I've observed on the wee Fiat engines. Yes, having the ability to infinitely vary the cam timing due to the cam sprocket being unkeyed means you can carry out basically the same "dialing in" (using locking tools in this case rather than the degree wheel and DTI guage to do it the "old" way - which, I would argue, would actually be a much more accurate way to do it) But I would argue that once correctly set up and the sprocket locked to the camshaft by tightening it's bolt simply renewing the cam belt, even including a new water pump, would not have any material effect on valve timing. Only a manufacturing intolerance in the placing of the water pump spindle in relation to the casting it runs in would make a difference to the timing and I think that highly unlikely. The tensioner, being on the "slack" side of the drive, would not affect timing and the belts themselves, as long as you buy a "big" name, have no dimensional differences I've been able to detect.

So I think, and have proved to my satisfaction, that AS LONG AS THE CAM SPROCKET IS CORRECTLY ALIGNED ON THE CAMSHAFT BEFORE YOU START you can correctly achieve accurate valve timing without slackening the cam retaining bolt and marking the belt, sprockets and casings (casings just for extra security of reference) before removing the old belt, transferring the markings to the new belt and reassembling.

I would also say though that unless you have a very good understanding of what you are doing I wouldn't do it this way because if something goes wrong during the change - and I can think of a number of possibilities - unless you understand intimately the 4 stroke cycle and how it relates to your engine, you're probably going to end up with seemingly insurmountable problems and possibly, on later model "interference" engines, a ruined engine.

One of the problems I've seen reported, here on the forum and elsewhere - there was a post not that long ago about this very problem, is that, even when using the locking tools, people end up with the timing one tooth out. A recent feature in Car Mechanics Magazine, where they did a feature on changing the cam belt on this very engine, ran into exactly this problem and it took them 2 days to figure out what they were doing wrong. It was obvious that they were following the instructions I posted a link to earlier in this thread which uses the locking tools but does not recommend slackening the cam sprocket bolt. The problem then arises that the locking tools are, of course, installed before slackening the tensioner so the cam belt is in a tensioned state when the crank and cam are locked up with the timing tools. So slackening the tensioner allows the old belt to be removed easily but when you try to fit the new belt you'll only be able to get it on the sprocket teeth in a one tooth retarded position. You'll never be able to pull the belt tight enough with your hands to get it on in the right position, I know, I've tried! What you have to do is remove the little bolt that holds the end of the crank locking tool to the front of the engine and turn the crank slightly anticlockwise - little more than the diameter of the bolt hole should do the trick - until you can slip the belt on. Having done that you'll find you can turn the crank clockwise slightly again to remove any slack and you'll find, once you've adjusted the tensioner, that the retaining bolt will slip back in.

I'm suggesting turning the crank anticlockwise above aren't I and people get very upset about turning crankshafts against their normal DOR (I've worded it carefully this way because some engines don't run clockwise). Yes, under 99% of normal situations DO NOT TURN CRANKSHAFTS AGAINST THEIR NORMAL DIRECTION OF ROTATION. This is because a worn belt/tensioner or chain/tensioer is much more likely to "jump" a tooth or several if the engine is turned backwards and this can be catastrophic for many engines. However, in this unusual situation we are not talking about more than a few degrees of crankshaft rotation and there is no risk of valves and pistons touchingBy the way, if you are in the habit of leaving your car in gear on a hill then engage a low gear compatible with the direction the car is pointing. What do I mean by that? If the car is facing downhill then select first gear and if facing uphill then select reverse. Any resistance to movement being supplied by the engine's compression will still be felt - although this effect is pretty minimal in reality - but if the car does move then the engine will turn DOR and so the risk of displaced timing due to wear in the chain/belt/tensioner/whatever is avoided.

I suspect some people will want to come back to me on all this and I'm awaiting, with great interest and anticipation what now may follow! However I'm off down to see Steven at the wee Honda Garage now to thank him for referring me to the Mobile Tyre guy and for a wee chat - also gives me a nice hour or so of walking along the old railway line, now a walkway, which will get me home mid afternoon just in time for a nice cuppa and a chocolate swiss roll with Mrs J in the garden. Maybe tomorrow before I can reply - should a reply be warranted. Hope you enjoy the above as much as I've enjoyed thinking about it.

 

[jrkitching]

And the whole point of a keyed pulley is that is doesn't change. Fixed once and stays put. I've seen engines where the cam pulley has slipped, even keyed the pulley should be torqued pretty high. It's not like we are talking about fine tuning a high performance engine, it's a 1.2 8v runabout engine.

I'd agree; this sort of fine tuning isn't going to provide any great benefit on an engine of modest performance, but it does create numerous opportunities for things to go wrong. The timing errors that will result from not precisely following the correct procedure for tensioning the belt are likely greater than those that will result from any small difference in component tolerances, particularly if you use a decent belt & tensioner.

Made worse by the addition of VVT and higher compression; at least with the original design, it didn't break anything if the cam sprocket did loosen in service. On the 500, it'll wreck your engine.

The Euro4 169 Panda is probably the last of the Fiat's I'd want to keep into old age; the 500 is just too much of a maintenance liability, particularly the higher spec variants.

 

[vexorg]

But I would argue that once correctly set up and the sprocket locked to the camshaft by tightening it's bolt simply renewing the cam belt, even including a new water pump, would not have any material effect on valve timing. Only a manufacturing intolerance in the placing of the water pump spindle in relation to the casting it runs in would make a difference to the timing and I think that highly unlikely. The tensioner, being on the "slack" side of the drive, would not affect timing and the belts themselves, as long as you buy a "big" name, have no dimensional differences I've been able to detect.

Usually there's no option to adjust on the side from cam down to crank, always a fixed length.

One of the problems I've seen reported, here on the forum and elsewhere - there was a post not that long ago about this very problem, is that, even when using the locking tools, people end up with the timing one tooth out. A recent feature in Car Mechanics Magazine, where they did a feature on changing the cam belt on this very engine, ran into exactly this problem and it took them 2 days to figure out what they were doing wrong. It was obvious that they were following the instructions I posted a link to earlier in this thread which uses the locking tools but does not recommend slackening the cam sprocket bolt. The problem then arises that the locking tools are, of course, installed before slackening the tensioner so the cam belt is in a tensioned state when the crank and cam are locked up with the timing tools. So slackening the tensioner allows the old belt to be removed easily but when you try to fit the new belt you'll only be able to get it on the sprocket teeth in a one tooth retarded position. You'll never be able to pull the belt tight enough with your hands to get it on in the right position, I know, I've tried! What you have to do is remove the little bolt that holds the end of the crank locking tool to the front of the engine and turn the crank slightly anticlockwise - little more than the diameter of the bolt hole should do the trick - until you can slip the belt on. Having done that you'll find you can turn the crank clockwise slightly again to remove any slack and you'll find, once you've adjusted the tensioner, that the retaining bolt will slip back in.

That was going through my mind, anyone that's done a conventional belt setup goes through the process of "why the f**k doesn't this fit?, is it the right belt?"

New belts take a lot of fighting to get them on. How are you supposed to tension the cam pulley if it's not locked. I much prefer it once you have the belt on then you know the only part to check is the tensioner.

 

[maros]

It's a straight forward job to change the cam belt - the trick is NOT undoing the cam sprocket - once you do that, you create problems. Instead, Lock the cam and crank at TDC using a cheap tool from bay (£10) and it's a doddle.

I recently replaced one on a 12 year old (2009) / 70,000 miles fiat 500 that was the original belt (confirmed by the previous owner who'd owned it from new and never had it done). The belt was still fine - unlike the accessory belt which was starting to perish.

I'm no mechanic by the way - and I changed mine on my driveway with a basic toolset, and it took under 3 hours including water pump. And a Continental kit including belt, tensioner and water pump was £66. The cam tool was £10. And a tube of sealant for the water pump was £8. So £84 all-in.

Bear in mind that garages will get the parts at trade prices and with all the tools/ramps/equipment/experience at their disposal, the job would take under 2 hours. So charging £400 for the job must equate to around £175 an hour for their labour....!

 

[vexorg]

Lock the cam and crank at TDC using a cheap tool from bay (£10) and it's a doddle.

What kit did you use?

 

[maros]

It was off eBay - consists of two items : 1. a simple bar with an angled insert that fits in the cam (opposite end to the pulley) to lock the cam - and 2. a bar that bolts to the crank pulley (3 bolts included) and then locks to the lower cambelt cover bolt hole to lock the crank in TDC.

Once those are in place, it's safe to remove the belt and tensioner and replace. Once you've replaced them, remove the kit and rotate the engine by hand a couple of times and then re-apply the tools to check everything still aligns. If it doesn't then the new belt is a notch out (easily done if you don't tension between the crank and cam properly). Simply take the belt off, lock the tools in place, and try again.

 

[John202020]

Sounds like that type of kit could make it possible for me to replace ours that needs doing next year along with the (water pump that will be 13 years old by then) always gone with a garage for the cam belt Fiat did the last one at £215

 

[maros]

The only other "specialist" tool you need is the pronged lever to adjust the tensioner. I didn't have one of these so quickly made one out of a strip of metal and two small allen keys... But if you want to save hassle, buy the correct tool for under £10 from eBay.

Apart from that, just remember - DON'T UNDO THE CAM SOCKET!!! Some guides (e.g. Haynes manual) tell you to do this and (a) if you don't have the proper tools you risk snapping the camshaft as the bolt is very tight and (b) it causes phase problems. It's simply not necessary - assuming the existing belt is correctly fitted, just lock everything in place and swap the belt in situ.

 

[Pugglt Auld Jock]

The only other "specialist" tool you need is the pronged lever to adjust the tensioner. I didn't have one of these so quickly made one out of a strip of metal and two small allen keys... But if you want to save hassle, buy the correct tool for under £10 from eBay.

Apart from that, just remember - DON'T UNDO THE CAM SOCKET!!! Some guides (e.g. Haynes manual) tell you to do this and (a) if you don't have the proper tools you risk snapping the camshaft as the bolt is very tight and (b) it causes phase problems. It's simply not necessary - assuming the existing belt is correctly fitted, just lock everything in place and swap the belt in situ.

I'm very much "in sync" with what maros is suggesting here and I did both our FIRE engined Fiats this way - actually just used tippex (but did use the timing tool kit to double check, when I'd finished, that the cam timing was correct as I'd not previously done belts on either engine. In future, now I know the cam sprocket is correctly installed, I'll have no hesitation in doing the belt without loosening the cam sprocket bolt - which will also make the job quicker because I won't be removing the cam cover, with all the associated hassle of "messing" with the battery and/or coils and their mounting plate. Also a small cost saving as the cam cover gasket and oilway "O" rings remain undisturbed thus saving the cost of replacing the gasket and oil seal "O" rings. Although, to be fair, it's not unusual to find the gasket leaking so you may want to replace it anyway.) One of my main approaches to doing car repairs and maintenance is to "let sleeping dogs lie" and "don't fix what ain't broke". That big bolt on the end of the cam is definitely a "sleeping dog" in my eyes.

By the way, If you don't have the "proper" tensioner adjusting tool then rather than buying an "ebay special" I'd suggest buying a pair of right angled circlip pliers. Here's a picture of the "official" tool alongside my circlip pliers:



The circlip pliers can be adjusted to fit different tensioners whereas the "official tool is fixed and there have been reports on the forum of the "official" tool's prongs breaking off. I've done a fair few different tensioners on different engines using the circlip pliers without any problems - and, of course, when you've finished you've then got a very handy addition to your tool kit that can do more than just adjust Fiat cam belt tensioners!

 

[vexorg]

It was off eBay - consists of two items : 1. a simple bar with an angled insert that fits in the cam (opposite end to the pulley) to lock the cam - and 2. a bar that bolts to the crank pulley (3 bolts included) and then locks to the lower cambelt cover bolt hole to lock the crank in TDC.

Does that tool still need the cam cover off?

 

[Pugglt Auld Jock]

The tensioning tool is used on the tensioner bearing so on the belt end of the engine. So, no, the cam cover does not need to be removed to use the tool, but the belt covers do.

The cam cover needs to be removed so you can insert the cam locking bar (tool) into the end of the camshaft if you are going to use the "official" kit to lock the engine up. Also, if you are going to slacken - and subsequently tighten - the cam sprocket bolt you need to hold the camshaft to stop it turning whilst applying effort to the bolt DO NOT RELY ON THE CAM LOCKING BAR FOR THIS, you'll almost certainly break bits off the end of the cam - That cam sprocket bolt is VERY tight to undo and needs to be very tightly done up again to ensure the sprocket does not spin on the camshaft during running. So remove the locking bar when slackening or tightening.