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Long-Interval Service Items - "Sprich zu mir"


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Why is it that factual dispute always quickly gets interpreted as personal ?

 

What fragile egos we all have.

 

That said, despite appearances to the contrary, I do respect peoples experience.

 

Granted I wasn't sure what the fuel tank material was on the Fab, but does that really inhibit me questioning the other monoliths of the VAG belief system. After all, they got EGR systems wrong, big time, on this generation of engines and that's with all VAG's accumumated expertise and multiple successive redesigns of the wheel.

 

And whose to say that overtime and without inspection and cleaning the pressure regulator, which is on the "Dirty" side of the fuel filter circuit won't get blocked with residues ?

 

In the days when I did my own servicing, you could still see a substantial part of the original yellow colour of a used filter when it was removed. The new type FF is now made of metal (Presumably to give it increased resilence in its new location), so you can't visually inspect, even when underneath the car.

 

Surely, the VAG philosophy should be, especially when dealing with in-line systems,  that you remove a used part while it is still serviceble, not wait until it becomes unserviceable. By that time its too late and danage has been done to other components.

 

I just think that given sufficient input pressure, you could force most things through a paper filter, especially when the EMU doesn't monitor the pumps input pressure to the filter.

 

Or are we saying that the filters have 100% integrity and effectiveness under all conditions ?

 

N

Edited by Clunkclick
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Usual.

 

Resort to insults when one's unable or unwilling to answer to the question.

 

All I'm saying is that on the old carburetted Golf, you didn't need an EMU to tell you something was wrong with the FF.

 

The FF was in the engine compartment, you could visually inspect it - its was made of transparent plastic, you could see the insides and the filter "At work". And, yes it did have a fuel return to the tank, except it operated from the Carburettor float chamber. So the fuel line from the tank went FF, Carburettor,  with excess fuel  going back to the tank when the float in the carburettor float chamber rose to the top of the chamber( When the chamber was full of fuel) and closed the valve to divert fuel back to the tank

 

You could see, from visual inspection of the engine compartment, whether the FF was knackered or the return line blocked, as it usually leaked when this happened. Now you have to rely on partial and incomplete second-hand data from the EMU. Brill.

 

Under this system, all VAG have done is saved 14 foot of rubber-hose in the excess fuel return line and made servicing 5 times more time costly and difficult and that production line saving may be  offset by the fact that they now have to make the fuel filter casing out of metal so as to resist the effects of life under the car - incidentally, did anyone notice in the video that the undertray protection that had to be removed from that A4 didn't even cover the fuel tank or the FF !. Way to go VAG !

 

N

Edited by Clunkclick
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Usual.

 

Resort to insults when one's unable or unwilling to answer to the question.

 

Absolutely not, it's an old proverb, not an insult.

 

Two things for you to consider, firstly; I'm a professional engineer and speak from a basis of qualification, training and long experience, and secondly; I'm not selling anything, simply providing factual information.

 

If you can tell me WHY you think the information I've given you is wrong then I'll be happy to provide a detailed explanation, other than that you have no basis to doubt the veracity of my statements so why are you arguing?

 

Edit: Incidentally, I replaced the fuel filter on my Fabia recently because I had a high speed misfire, it turned out to be the coil pack (again) but since the fuel filter with a new regulator built in was only £10 and it took 5 mins to do I figured it was worth a try, the fuel filter I replaced was the original and loads of dark grey sludge came out of the tank inlet meaning it was doing its job beautifully.

Edited by sepulchrave
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Well,  to be honest, I've heard plenty of people call themselves "Qualified engineers" only to find out that later that their principal employment involved them mending toilets in public facilities, or refitting garden gates.

 

 

I would presume that you haven't got VAG training or experience, otherwise you'd have stated it.  Guess what, neither have I.

 

As all these manufacturer will all have their own ways of implementating engineering solutions based on their own in-house justification, its unlikely that anyone will know, definitively, outside VAG, why a particular system was implemented in a particular way - some of it may even be  patented or trade secret.

 

Therefore the best anyone can do is speculate using common sense and practical home mechanicing, in the best traditions of this web-site. I don't think discussion is reserved for "Profesional engineers" only.

 

We would hope that the lesser educated of us would benefit from the dissemination of info by those on the forum that had, by one reason or another acquired greater experience or knowledge, providing that was done in not too imperious a manner.

 

So its pointless getting into a corporate mentality ****ing contest about the relative merits of experience, as is oft favoured on this medium.

 

 

Anyway to get back on sub-topic.

 

It seems to me that re-locating the fuel filter to underneath of the vehicle and changing the casing to metal is counter-productive in a number of ways.

 

Primarily, it elevates production costs - does one £4 plastic fuel filter + 14 feet of return flow rubber tubing cost more than a £25 metal filter ? No.

 

Is it easier to diagnose faults, service and maintain,  in all respects. No. It can't be easily visually inspected without putting the vehicle on a ramp and the internals are not visible.

 

Is its method of operation inferior to the old system ? Yes, because, it looked to me from the cutaway in the video, that in the case of an over-supply of fuel, which is being the most frequent occurrence (Because the R.P.M. of the electric fuel pump is fixed and doesn't synchronise with engine RPM) that fuel was returning unfiltered to the tank, hence running the risk of blocking the return-to-tank circuit. This wasn't the case with a carburetted Golf because all fuel was filtered before returning the excess to the tank. This risk would increase with older cars (More time to accumulate gunk n the tank) and weaker suspension, meaning more shaking about on our increasingly wonderful roads. And there was no sump trap in the fuel tank.

 

N

Edited by Clunkclick
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Here's a diagram of the fuel filter as used on petrol models with no return line in the engine bay.  This is from VW information acquired from the web, not speculated on by anyone.

The return appears to be filtered. Hope this helps.

 

Fuel%20filter.jpg

 

Seems like a neat bit of engineering to me. Keeps the engine bay fuel volume to a minimum, which seems logical from a fire-risk viewpoint.

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Many thanks.

 

I knew I'd get some benefit in the end !

 

That leaves my points 1 and 2 unanswered,

 

Engine bay protected from increased fire risk (What about the injector pump reservoir ?)  possibly but those poor rear seat passengers in the A4 will get toasty goolies if a flint off the road hits that filter head-on - no undertray protection. Is there an undertray for this purpose on the Fab ?

 

N

Edited by Clunkclick
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What's an injector pump, and what's its reservoir? If we're talking about petrol engines, do you mean the fuel rail?  Not really an avoidable volume.

 

I think he means the fuel accumulator as found on K-Jet cars from the 70's and '80's, I really can't be bothered any more, he's both rude and ignorant, I've given best advice and have nothing more to add. I'm out.

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So this stuff?

 

"It seems to me that re-locating the fuel filter to underneath of the vehicle and changing the casing to metal is counter-productive in a number of ways.

 

Primarily, it elevates production costs - does one £4 plastic fuel filter + 14 feet of return flow rubber tubing cost more than a £25 metal filter ? No.

 

Is it easier to diagnose faults, service and maintain,  in all respects. No. It can't be easily visually inspected without putting the vehicle on a ramp and the internals are not visible."

 

I'm not sure about the first, about production costs.  On the Mk1 Fabia 1.2 engines, as far as I remember, the 6-valve variant has the more traditional set-up for petrol injected engines, with local pressure regulator on the fuel rail, and return line, with 'simple' filter near the tank. The 12-valve has the system discussed above, with integrated filter and pressure regulator, with no return line from the engine bay.  I'm not sure why they're not done the same way to be honest, maybe just that the 6-valve design pre-dated the 12-valve. More 'stuff'  to go wrong in the engine bay, a higher risk area for fire, is my best guess as to why the change was made away from the traditional system.

 

As for maintenance, service, and fault finding. Dunno, never tried on the Fabia. Did have trouble on a carb-engine Golf once when the plastic housing of the filter split slightly at the top and let air in. That produced a very hard to diagnose cutting-out problem; so I'm happy to have a metal cased version instead, far from the exhaust manifold, instead of inches away.

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I'm all for helping people understand stuff, if/when I can. I hope to find likeminded individuals in any forum I participate in, and haven't been disappointed to date. I've learnt an unbelievable amount about cars in the last 8-10 years, from a starting point near zero, due to the generosity of such individuals.

It's tempting to not put in so much effort though, when someone initially 'goes off on one' rubbishing designs that they only have the slenderest understanding of.  Maybe that's my shortcoming.

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Well, by the sound of it,  you've spent considerable time and effort gaining the inside edge on VAG servicing, you hold on to it, and the moral highground, son !

 

 

Aside: Yep, just as sniffy as the technology forum.

 

 

N

Edited by Clunkclick
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Remember folks, this is the same "Safety First" VAG doctrine that determined that the best place to put the fuel tank for the LT van was under the driver's seat (And, of course, it got DOT Type Approval at first pass !). This had some interesting results in accidents.

 

Personally, I'd rather not have a filter in my wagon that colour, even if the VAG EMU deems it is still serviceable. If I was doing the servicing on my old Golf and I came across a filter that colour, I'd change it, that, of course, would be after administering a swift punch to  my own head for allowing it to get in that condition in the first place.

 

 

Postscript

 

Annual service reminder card has just come through the door.

 

 

N

Edited by Clunkclick
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From a customer convenience point of view having the petrol filter fail unpredictably at a time determined by some invisible software ain't going to help me much when say  I'm half way to France on my annual holiday and the thing throws the usual undecipherable error code and tells you to pull over and turn off the engine.

 

I'd much rather replace on a preventative basis, as was the regime with older vehicles.

 

So whilst the current system ticks all the boxes for "Trained engineers" and dealers (All that unexpected, "I need the car now" premium rate business) it does nothing for me in terms of Customer Service.

 

This may be a complete revelation to VAG - but I understand that the major commercial aircraft companies have been running predictive and preventative maintenance using information from constant in-flight diagnosis (Which is radioed ahead to the next port-of-call with a service facility) for some time.

 

A bit like the 2001 movie " Dave, the standby transmitter antenna is going to fail in 11.25 hours".

 

N

Edited by Clunkclick
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It's been in the Mk1 Fabia forum as long as I've been involved?

 

Dude, since you seem intent on making a fuss, here are a couple of points you may wish to consider:

 

1. If you find that everywhere you go everyone is 'sniffy' with you, consider the possibility that you are putting yourself across badly.

2. If you don't like VW Group products, vote with your feet and buy something else.

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Reading on further with this subject on the inter-web, including the other VAG forums in the UK, States and Worldwide,  I have been astounded by the unbelievable tales of woe of the number of long-standing combustion issues people have had with their petrol Golfs, vans etc which were eventually tracked down, after much heartache and fruitless  expenditure of money with main dealers, to a defective "Lifetime fit" fuel filter,

 

Generally speaking, these have been cases where the filter has become so clogged that fuel flow through the filter diminishes and the mixture "Leans-out" significantly. In one case of a golf in the States, he couldn't go more than a few miles without completely burning out a set of plugs. It would seem that if the fuel filter gets into this state and starts leaning out the mixture, then, at first instance, the ECU software conspires to "Hide" the problem (The Fuel "Trim" criteria in the ECU) by making other compensatory adjustments to keep the engine turning over. And, of course, in these circumstances, the error codes that are output are completely unrepresentative of what actually is happening. And the fact that there isn't a sensor on the fuel filter (Detecting permeability of the filter), means that owners and users go round in circles, replacing every other component on a semi-informed guess\hunch without resolving the problem. There are absolutely tragic accounts of people replacing sets of spark plugs, lambda sensors, throttle bodies, catalytic converters in a desperate attempt to remedy a problem that they haven't got any real firm idea on at the time and which turns out to be the fuel filter. And, by the sound of it the majority of staff in the dealerships Worldwide aren't much better informed - the best approach offered usually being darts/parts !

 

In the States, the forums are advocating changing the petrol fuel filter at anything between 40-60,000 miles.

 

IMHO VAG need to do two things:-

 

Issue formal advice Worldwide to bring this issue to the attention of dealerships, customers, owner/drivers and other interested parties and, secondly,  MAKE THE PETROL FILTER  A SERVICEABLE ITEM.

 

This would cost VAG nothing to execute, but would correct this issue for all time as well as saving owner/drivers a small fortune in unnecessary parts replacements. Of course they would lose  all this sales income from the unnecessary replacement of other more expensive parts which didn't solve the problem . . . .

 

If this is an unintentional design error by VAG then they truly are incompetent, including the trained design engineers at Wolfsburg, but its interesting to note that they haven't done this with diesels, the filter of which is a serviceable item and the main filter of which has been left in the engine compartment. Probably because there is more extraneous **** in the average tank of diesel. But there again, this is the company that thinks topping-up with one litre of engine oil every 600 miles is a practical and environmentally acceptable limit of cylinder bore wear.

 

 

Nick

Edited by Clunkclick
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I kind of played safe and bought a filter + fuel regulator + regulator securing clip, so that I could remove and replace these parts as a single assembly, I also bought a self sealing coupling repair kit - just in case!

 

For your interest, I replaced the simple filter on my old Passat V6, it had banjo couplings both ends, after about three years I was a bit annoyed to find a trail of fuel after reversing out of the garage on a very cold morning - reason - salt etc had cut an axial slot across the alloy filter case just where the inner banjo O-ring recess was - very annoying!! Next filter got coated with Waxoil to avoid that possibility - the original filter probably got coated with wax at factory when the car was being built.

 

I don't remember enjoying replacing the fuel filters on either of my Ford Orion Ghia Injections - hiding in the engine bay with very large banjo connectors and not much room to move the spanners!

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I'm going to request the main dealer replaces it at the annual service Of my car next month. Be interesting to see how much humming and harring there will be. There's always a hammer I suppose.

I think 12 years is more than enough for one filter and I don't want to be in the position where the thing suddenly goes unserviceable in the middle of a long journey. The trouble is if the EM light comes on, at the time, you don't know whether its something serious or not. So you are more or less compelled to pull over and call a recovery truck. I'd be a bit ****ed-off to find that it was just the fuel filter that had just cost me £200 in towing and garage charges during continental holiday.

I think they are having more problems earlier in the life of vehicles in the States because of the higher annual mileages they do on average over there. By the time the average UK driver has done 60,000 miles, a US driver is probably on 120,000 and at the service limit of these so called "Lifetime fit" components (Ascertained from the lifetime that Continental specify for the cam belts, 120,000). At 120,000 miles a US VAG Golf/passat etc is still with the first owner, whereas an equivalent UK car will probably be on its second or third owner in the UK. Secondhand car owners expect problems -cynical old VAG, eh ?

N

Edited by Clunkclick
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All I'm saying is that on the old carburetted Golf, you didn't need an EMU to tell you something was wrong with the FF.

 

The FF was in the engine compartment, you could visually inspect it - its was made of transparent plastic, you could see the insides and the filter "At work".

 

The fuel filter on a petrol fuel-injected car is under much more fuel pressure from the pump than a filter on an old carburettor equipped car. Therefore the filter casing has to be a lot stronger. Transparent plastic simply wouldn't be up to the job. I had an old M-reg Escort with fuel injection and the (metal) fuel filter was in the same place as the Fabia - near the rear axle beam. It's not just a VAG thing, it's the same on many petrol cars.

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