NeilTM

Yes, perfectly adequate power and the engine itself ran fine, and quietly - right up until we left it with Mr Clutch ;-) Only needs one weak link in a chain to spoilt the entire chain. And sometimes the entire chain is the weak link it seems. Far too many horrific weak links in cars these daze IMO.

Thanks for checking Damo. We read about a Ford Transit that this was an issue with: https://fordtransit.org/forum/viewtopic.php?f=5&t=105454&c=1 But in general it seems to be only a few engines where a worn TC tensioner can slacken the chain sufficiently to jump a tooth if turned backwards. The 1.2 engine in the Fabia is listed here as one of the worst 7 car engines for reliability because of the timing chain failing: https://drivemag.com/news/seven-engines-to-avoid-when-buying-second-hand-cars Which whatever the shortcomings of that particular survey might be is at least suggestive that a generalist garage is likely to have encountered or at least heard about this problem, on what seems to be quite a popular car on the road, and should be aware of these risks. And here, https://www.thecarexpert.co.uk/most-reliable-engines/ and in other surveys VAG cars have the worst engine reliability ratings apart from MG Rover, but they're long gone now, so they, or more specifically the Audi part of VAG are the worst there is apparently, averaged over a makers entire range of engines, based on interrogating Warranty Direct's claims database, so obviously some good, some bad amongst that lot for any maker. VW themselves come ninth worst, but Skoda specifically isn't listed in that summary, not all cars are represented in that survey if the numbers of them insured with them are too low, not to have the potential to constitute an inadequate sample and skew the results. With BMW not that far behind with TC issues of their own, not least having to hike the entire engine out of a car to get to their troublesome TC! Only Mercedes seems to redeem the Germans at third best.

Gosh, yes, I hadn't appreciated that the tensioner was oil pressure activated, as opposed to a spring, but that makes perfect sense as a damped, essentially hydraulic mechanism you would want it to be, and a spring would not deliver. What this also surely points to is that a timing chain jump in normal use is far more likely, perhaps even only possible at start up, when the functioning of the tensioner has not yet been fed the oil under pressure it relies on to function properly, or as you say a sustained push may have evacuated it. A momentary rock backwards on stopping the engine would have no effect as the device would be fully primed, even if worn, but may perhaps then evacuate it, setting it up for potential failure to take up the chain slack at next start up just as you say. But then the all important Q is in what direction would the jump occur, and the answer surely has to be that if the engine is cranked on the starter and fires and runs normally, throwing out the starter dog as it revs up, then the only possible direction of jump in that sequence is to get ahead on the chain, and any jump occuring will therefore retard the ignition. If the starting sequence is interrupted or fails, and the engine doesn't fire and run normally, then the engine MAY be permitted to run back a little way. It may run back a lot I suppose if there is the sort of kick back as could be experienced with a starting handle, where if you had your thumb wrapped round the handle and it kicked back, where the firing before TDC pushed the engine violently backwards, you could break your thumb as opposed to the handle flying out of your hand. A good question might be to ask whether such events are still possible with computer controlled spark and fuel injections though, I don't know. So maybe the question as to whether backward rotation of the engine at a failed start up might be sufficient to permit the engine a backward rotation sufficient to provoke a jump in the direction of advancing the timing, still relies on a difference of degree of backward rotation between a slighter (at start up), or greater, and more sustained (during dismantling) turn backwards? Hence my separate Q on this forum made in the hope of discovering if there was any consistency and in what direction the jump occurred when it happened at start up. I know that that car has always started reliably as most modern cars usually do, so it seems unlikely that there would have been a fluffed or failed sequence when my son started the car to drive it the approx 3.5 miles to the garage. But if it had jumped then it surely would not have run and idled normally enough, if at all, while the ECU learned new settings for idle and running, as my other daughter's fiesta had to do only the other day when it lost its VRAM running settings, and I sat and ran it to normal temp from cold, then left it alone for an hour or so before it would finally fast idle, before settling back down to normal on a short run. If this is so then this might provide additional reasons to those already stated why the jump did not occur before the car arrived at Mr Clutch as such running would have been inescapably memorable. The other stretch on that scenario would be to have to ask if it could really take as much as 8 or 9 miles for the ECU to suss the 20degree jump and put on the EML. But 5 to 6 miles at least it must have taken, so........? They now want to say that the broken clutch caused the jump, so I asked them 'how precisely'. At most the partially disengaging dragging clutch, which was insufficient to 'creep' the car forward at all, would simply add to the load on the crankshaft pulley, but unlike a piston under compression or the spring tension from the valve springs would not of itself provide any backwards impetus surely? Maybe even act as a damper on such movement?

Yes, I think I made this point myself. But clearly it must be a question of the degree of backward turn, if these routine events, at least every time an engine is stopped do not in fact result in a jump, then a clutch replacement does the trick. It seems perfectly possible that had the clutch needed replacing 30,000 miles ago, that this jump might have occurred during clutch replacement then, and by the same token that it might not have occurred for another 30,000 from now, if the clutch work was done then. Nobody has that crystal ball, and such speculation is unprovable and irrelevant. I seem to recall a similar issue with some alternators not liking to be turned backwards, but again that presumably refers to being turned back more than the little rock produced by cylinder compression being lost that way as you describe. Mr Clutch read my final much stronger reply to their brush off sent late last night and they replied early this morning saying that they were giving this to the local area manager to look at and get back to me asap, so hopefully they might be starting to take this seriously.

Indeed, a fascinating tale, also containing a little pearl of information about where to find VW tech info: https://erwin.volkswagen.de/erwin/showHome.do Private individuals can subscribe. Minimum subscription is for one hour access, so an expensive sounding pearl hire business. (the online info becomes inaccessible when the hire period expires) Anyone here already have access who could tell me if ErWin might have clutch replacement procedure information that might contain a warning about not allowing the engine to rotate backwards? late 2005 Fabia 1.2 BME engine.

Thanks Wino, I do appreciate everyone trying to watch my reckless back, LOL Nothing 'official' as such as yet, but if I have to find something then I will, if it is only the testimony of experienced mechanics undertaking this work, and here is an example of that I found online, http://www.bba-reman.com/forums/Topic108918.aspx?PageIndex=2 where the respondent informing of this backward rotation situation, and others in that thread reveal they are professional mechanics. I know that my local VAG independent would be happy to write testimony to the fact that this happens, and probably be prepared to share their procedure for ensuring that it doesn't, and even the mechanic who replaced the clutch did not contest that this could happen when I put it to him, nor their head office, only that he would not have made this error.

Now that sounds like a tale worth repeating!? Reminds me that when I took my 16yo Fiat Doblo with 150,000 miles on the clock in to a so far very impressive independent Fiat specialist, he pointed out to me that my aux belt was original! And sure enough this otherwise meticulously dealer serviced, single owner vehicle had not had this changed for the simple reason it never appeared on any service schedule to change it! Tell me VW made the same omission and that is why its failure to specify its change resulted in the demise of the engine?

You could well be right, but as my brother pointed out "With the defendant judging the case, I think the verdict is inevitable. I guess that's why we need courts." They don't teach logic in schools for a reason. While my logic might defeat Mr Clutch to understand it, the courts are a different prospect.

Thanks Wino, and others above. IF the only way the timing could jump in the direction of ADVANCE is by backward rotation, I don't see that it matters to establish at precisely what point or in what way this happened during the clutch work, and we already have demonstrated that getting honesty out of them is unlikely, so your questions would just get us hopelessly bogged down in fresh opportunity for their further obfuscation, without doing anything to reinforce the central point which I now made that the engine must have been rotated backwards for the TC to end up where it has, and their vague woolly account of how that could have happened as due to the severity of the clutch failure which they are simply egging for dramatic effect, and I am countering by demanding they get specific about how a broken clutch can turn an engine backwards as I don't see how it could. You are quite right about the effort and stress to get them to pay for this repair, but its already been largely expended, I've proved my case I think such that a court would accept my explanation and proofs over their vaguenesses and provably false narratives. The only way I could have avoided it would have been to accept being lied to and robbed from the outset, so I'm choosing my own source of misery since this way there is at least a chance that I might force them to take responsibility, if only for culpably failing to notify us of an additional engine running fault they are now claiming they were aware of before they did the clutch. This should get them their RAC accreditation taken off them as had they informed us, in accordance with those RAC standards as they should, of additional issues we would have investigated them, or had them investigate them first, and made a decision to scrap the car at that point as it would not have seemed worth spending a total of £618 with them on two major jobs on a car of this age, mileage and market value. We were entitled to the full picture they claim they knew existed to be fully discovered before doing only one of the jobs presenting themselves at that point, which makes no sense to ignore, but of which we were unaware. Instead, we got lied to in one of the two ways I have outlined, which itself is strongly suggestive of trying to cover up a mistake they made which triggered the TC jump. And there is seemingly no other contender now for the jump than the clutch work. I shall send an already completed draft reply to their brush off email to them now, so that it is waiting for them first thing Mon am inviting them to reconsider undertaking the full kit replacement TC & T without charge in another of their workshops, in light of me busting them basically, giving them until one working day before the appointment I shall be making to get the work done by our trusted local VAG independent, after which they will get the full bill, and I will take legal action if it isn't paid.

I realized that my own brother who used to in his own words "design the components and systems that go into a vehicle", his specialism being the electronics and programming side, might have the answers I was seeking as to whether battery disconnection could extinguish the EML even if the codes persisted, and he has come up trumps and with a lovely bonus that he feels proves how the jump occurred. This is what he wrote: "Having worked with the VW-Audi group, I can assure you that the standard functionality required of any ECU on their vehicles requires DTCs to be held in non-volatile EEPROM or 'E-squared' as it is often called. This requirement is, to the best of my knowledge, industry-wide and has been so for over 20 years now, so the Mr Clutch people really should know better! The Engine Management light is then controlled by the instrument panel after it is signalled to do so over the CAN bus (the instrument panel does not have to 'remember' the status of the light itself.)" EEPROM: Electrically Eraseable Programmable Read Only Memory I still wasn't entirely sure that what applied to the codes also invariably applied to the presence of the EML but he assures me that in these circumstances - of a permanent fault such as the timing chain jump it does: "A fault such as a 20° timing chain jump is not intermittent, so once detected by the engine ECU, would be permanent. The EML would be on continuously - end of story. Intermittent faults are recorded with DTCs that are flagged as intermittent and an incidence count is maintained for those faults and the EML could come and go or take some time before it is lit - but this fault isn't and cannot be intermittent, so that cannot apply here." He further stated: "I know there was a requirement, (in the specs the car manufacturer gives to the developers), to remember DTCs through power cycles and that includes units that were not supplied with a permanent battery live. (that's the Fabia as Wino pointed out) The only practical way to do this is to store them in some form of non-volatile memory, so that is what is routinely done. To the best of my knowledge this has been a requirement in every car manufacturer's specs on this planet for over 20 years." I really hope anyone and everyone struggling with being mislead over the permanence or transience of codes and EMLs can find their way to read this as it lays a lot of myths to rest and introduces certainty into a picture where ignorance may otherwise be exploited. So I now have categorical proof that their account could not have happened as they said. Either they lied about the EML being on before work commenced, or they lied about how it came to be off after the work, as the only way it could not have remained on was if they deleted the codes, either of which is a serious untruth amounting to deliberate fraud designed to evade any responsibility for this event and put it entirely on the customer. But it gets even better, (or worse for them) if you ask what type of event is necessary to cause a timing chain to jump, such that the direction of the error, as in this case is towards the timing becoming ADVANCED? My brother again: "the direction in which the 20° jump has happened: Given that the motive force for such a slip can only come from the crankshaft, the camshaft being the load, so if the valve timing is now 20° advanced, that proves it can only have happened by turning the engine backwards and how would have that happened (in this instance) other than during clutch replacement?" I had to sit down with pen and paper to visualise this, whereas a child's toy set of sprockets and chains might have helped considerably to model this, but he is right, the crankshaft has to end ahead of the game with the camshaft, with the motive force being engine rotating clockwise, and vice versa if moving counter clockwise by the same principle. Remember the camshaft is a significant load, it is constantly opening and closing valves against strong springs, so it is a significant resistive force opposing the crankshaft turning it. With the crankshaft jumping ahead of the camshaft through the slackness of the chain, the camshaft becomes behind in sequence to the crankshaft, ie its valve work is RETARDED. But if the motive force of the crankshaft is counterclockwise, the engine being turned backwards, the same principle determines that the jump will occur in the opposite direction, and ADVANCE the timing. The timing on our car is now ADVANCED, therefore the jump was produced by the engine being turned backwards. And how can that happen? By turning it backwards during clutch replacement work! And we don't think it is possible to visualise a scenario where a broken clutch release mechanism can cause the engine to move backwards as they now claim. Are we wrong?

Where people have reported incidents of timing chain jump, on any vehicle, whether at start up, or after cranking an engine, or during clutch replacement, has anyone recorded which direction the jump occurred in? Did it leave the timing advanced or retarded? Please be clear about the precise circumstance in which the jump occurred if able to report whether the timing became advanced or retarded. Thank you.

I am reproducing below the essentials of the Mr Clutch response which took them exactly the promised fortnight to come up with. Right arrowed is their text, with my comments and questions inserted: On 12 Dec 2019 at 11:33, Customer Services | Mr Clutch wrote: > Dear Mr Taylor, > > I am writing to you further to your email dated 27th November 2019. > > We would like to respond as follows. > > The sequence of events : > > Your vehicle came to us on the 13th November 2019 for diagnosis and after > a very quick test in the car park without moving the vehicle we could > ascertain that the clutch had catastrophically failed and was > undriveable. > That is egging it a bit as we drove the car to them. The clutch was working but dragging - not fully disengaging and as we thought, they stated that it was a broken clutch release mechanism. ......... > It was noted that there was an EML light on and the engine was slightly > rough in running before we stripped the vehicle. This was first mentioned only after we had diagnosed the timing chain jump and reported this to them. Only then did they change the narrative to claim that the light was on when they took the car into their workshop. But when I asked why it was not still on upon receipt of the car after the clutch work, they falsely claimed that disconnecting the battery lost the codes. This we tested by disconnecting the battery for a whole day, whereas their work took 5 hours. The EML and codes were still there upon re-connection without re-starting the engine. Therefore either they lied about the EML being on before their work, or they lied about deliberately deleting the codes since that would have been the only way they would have disappeared and the EML extinguished. > However, due to the severity of the clutch failure we presumed that > the two were linked in the same way. The EML light was on because the clutch was broken? How does that work? > After replacing the clutch the > engine was smooth on the idle, however did lack performance when > tested. No light was on at this stage and all work we carried out was > rechecked. > So after demonstratig to them that this narrative doesn't stand up - couldn't have happened - they simply repeat it, merely omitting the bogus battery disconection explanation given at the time! They are not coming up with a possible narrative. I also reported their stupid forced revving beyond the ECU imposed 3,000rpm limit, but they've just blanked that. > The car was collected from our Autocentres and advised suspected catalytic > converter blocked, due to symptoms we had experienced, had we plugged in a > diagnostic machine at this stage and retrieved the codes you retrieved out > of the vehicle then it would have pointed to the timing chain and not the > catalytic converter and we would have advised accordingly. > Which begs the Q as to why they didn't do this, and do it before the clutch work, since it is trivial to do and takes a few minutes at most, yet they apparently had time to rev the engine and repeatedly force it with a 'pop' to go beyond the 3,000rpm limit after the clutch had been changed. Only after the clutch work did they show this much interest in the engine running. > With reference to the technician concerned he is a long standing employee > of many years with us and is not a liar, he is part of our National > Support Team and is held in high regard. > And Popes are infallible too. I caught him in a lie, so why not use the word, when it is demonstrable? They on the other hand have implicitly claimed that we were lying by claiming a prior engine management light that never was, but still fail to provide an explanation when challenged to account for it disappearing during the clutch work. > To reiterate the information the poor running was due to the clutch > breaking up and not any other problem, we refute causing the problem of > the timing chain failure and could have been caused due to the severity of > the clutch failure. > Apart from this not being a grammatical sentence, but I'm assuming a missing 'it' between 'and' and 'could', can anyone tell me if a broken clutch release mechanism, preventing full disengagement of the clutch, such that the gears crunched when getting into first or reverse could cause the timing chain to jump? Has anyone heard of this happening? The thought that this might be possible occurred to me before it apparently occurred to them, since they have taken until now to relay this possibility. But is it a possibility, in which case what is that scenario - how does that work? If anyone has ever hand cranked an engine with a spanner, or a starting handle for that matter, they have probably noticed that if this hand cranking is ceased while a piston is approaching TDC on the compression stroke, that the pressure built up might result in a slight backward turn of the engine. This can also occur if the starter motor is released prior to successful firing and running of the engine can it not? Is this slight backward rotation what can cause the TC tensioner to 'unload' its tension, allowing for a then slack chain to jump? I am assuming that since this particular car never had any starting issues, always firing and running straight away, that this scenario simply never occurred to allow for a TC jump? I would also like to know if there are any professional experts out there that anyone knows of who might be able to give a definitive opinion on this Q such that a court would take them as an expert witness? Who could I turn to for not merely a legal opinion, but an opinion of a qualified technician or engineer, or a technical document? If they are trying to fudge the issues of the codes, as opposed to just being too stupid to understand what they are talking about, then it would be good to have an authoritative reference about the non volatility of these codes. By miserable coincidence, the other day my son in law used his fiesta as a torch with which to light up the front of the house putting up xmas lights, then forgot to turn the headlights off. The resultant voltage crash lost the apparently volatile (VRAM) engine running settings, such that when I got the car started after re-charging the battery it wouldn't idle. It eventually re-learned its settings and was OK again. But I'm still assuming, and our experiment confirmed that this does not apply to engine sensor codes such as camshaft etc? > With regards to the EMC light coming on, it can vary how quickly the light > comes on and there is no set time or mileage. > Yes, or at least that's what I've heard, but irrelevant. What I asked them to account for was the *disappearance* of the EML during the clutch work. > Taking the above into account we are more than happy to carry out the > repair for you but we cannot do it free of charge. > Now that it seems we are potentially going to have to take them to the small claims court to get a bill for fixing this elsewhere paid, I need to have expert testimony that I have a good case on the central points above. I think the failure of their narrative, and simply repeating it without offering any explanation in place of the one I demonstrated to be false, suggests that my exposure of that falseness is not possible to get round without liability, if only because being caught in a lie destroys the probability of the jump occuring before the car landed on their forecourt as they claim, and makes it much more probable that it occurred during the clutch work which they simply refuse to entertain the possibility of. Why lie about something that wasn't their fault? But also their failure to notify of the engine fault revealed supposedly by the EML being on before commencing the clutch work? Can a broken clutch release mechanism put up a code? Not notifying us of other issues before undertaking major work contravenes their RAC approved garages accreditation, but their chocolate fireguard remedy involves binding adjudication, a process that apparently can take up to 3 months, so nothing to do with getting a needed car back on the road in a timely way, and so unlikely to ever be invoked much I imagine. Any information and advice on the above would be much appreciated.

Battery disconnected all day. Re-connected, codes and EML still there. Dealing with a BS merchant. No time to deal with this on Monday, so will tackle manager Tuesday.

My son is testing the possibility that the codes were erased by the battery being disconnected, by doing the same, and we'll know the answer later today. My son wrote to me: "I .... asked him to explain the issue where he described the engine struggling to rev above 3000rpm though he said could do after trying for a little while at which point it gave a "pop" and would then rev higher (not our experience). At no point in that conversation was EML mentioned by either of us." This in itself is worrying, as it seemed obvious to both of us that a rev limiter bang on the round figure 3000 mark every time would be an ECU limit introduced, so trying and apparently succeeding to make it rev higher with a 'pop' sounds alarming and irresponsible, and makes me wonder if any damage might have been done by doing this? They also said to my son they would have to read the 'historic codes' when it came back in for assessment, logically thereby also claiming they never read them when the engine management light was on, which they never mentioned at all to my son, or reported it having been at any time whatsoever until I went in with the car, informing me only then that it was on when they first started the car.

Just wanted to bump this one of my original questions: So my first Q is how long is it likely before the ECU would recognise the persistence of a fault, as opposed to a transient, before logging trouble codes and putting on the engine management light? The delay experienced was a 2 mile journey home, plus approx 1.5 miles into a trip the next day before it came on? Is this a possible delay? Might actually have been 4.5 to 5 miles. The rough running and 3,000rpm rev limiting were certainly there from picking up the car.