 A screw
We often hear that today's vehicles are no longer as repairable as they used to be. Is that an argument based on laziness and/or because you have enough money? The fact is, of course, that cars have become more
complicated, and you have to be extremely careful that the cost of repairing them yourself does not exceed that of authorized repair shops. However, there is no shortage of advice, even if it is not always wise.
This will now be demonstrated using a specific case. Imagine a highly unusual maldevelopment. Someone gets stuck in traffic in the summer heat in front of and in a construction zone. Since he is in a great hurry, he
presses the accelerator a little harder. Just as the Fiesta in front of him makes room and he could really get going, his engine loses power.
The engine warning light turns on and he has his hands full changing from the left lane of the three-lane highway to the hard shoulder. It is the beginning of a long enmity with the diesel injection system. Somehow he
notices that the engine is still running and that there will be a parking space shortly. So hang in there and keep puttering along until then.
Of course, opening the hood does not reveal any results. Everything looks normal. By the way, the engine is still running. So, get in the car and drive to the next exit. Slowly but surely, you get used to what is called
'emergency mode'. Revving an engine above 2000 rpm is punished with braking refusal. If you shift gears in time, the next gear will hardly get out of the slippers.
That was obviously exactly what the VW engineers wanted. Driving in emergency mode is supposed to be discouraged. Such a four-cylinder engine then does not have the power of a three-cylinder engine, but rather that of
a one- or two-cylinder engine. With great difficulty, you just manage to escape the trucks on the flat track. Uphill, it becomes downright dangerous. On the way home, there is a hill that eventually slows the speed down to 60
km/h, on the highway, mind you.
Luckily, it's Saturday. But at this low speed, yet a few trucks accumulate. Thankfully, the escape to a rest stop halfway up is successful. Getting out of the pit lane without trucks is proving difficult. It is best (and above all
safer) to drive on country roads.
After arriving home without any further problems, it's time to start troubleshooting. If you don't already have a readout device, you can make your first mistake here by buying one that can only do that. Why? Because it
indicates a defective injector as the cause, which then has to be replaced somehow and the replacement has to be communicated to the control unit. If your newly purchased device cannot do this, you will have to take it to
a repair shop or buy another device just for this purpose.
Slowly, very slowly, we are approaching the crux of the matter, which is still far from certain for the inexperienced repairer. He is just making sure that the diagnostic device is telling him the truth.
And since (at VW) two injectors are always attached together, he changes those from cylinders 1 and 2. In this case, removing them is not a problem, as the engine has not yet run 50,000 km.
Why an injector would fail can only be answered by an analysis from Bosch Service. Unfortunately, he could not comply with the request to repair the injector and send it back, because the circuit was defective. So he puts
together another one and sends it, which ends up being slightly more expensive than previously advertised on the internet. But still miles away from the workshop price.
kfz-tech.de/PDM54
Since the 'new' injector is under warranty, you might not install it right away, but instead turn the fuel line and injector so that it injects into a larger glass container where it can be observed. Without the plug attached, you can
now see whether it is tight, and with the plug attached, you can at least ensure that it atomizes and does not 'dribble'.
It works amazingly well, so it can be installed. A new copper gasket is also included. Unfortunately, however, none for the second, intact injector. Actually, it's time for a trip to VW, because the expansion screw between the
two injectors should always be replaced. Incidentally, it is only around this time that VW's requirement to also replace the fuel injection lines is canceled.
Our participant only learns all this much later, when the difficulties start to pile up. So far, he is still so optimistic that he leaves the seal on the second injector and installs the injectors with the existing screw after
provisionally cleaning the sealing seats. And what about torque? The last time I was asked at a trade fair stand to tighten a wheel bolt to 100 Nm by feel, it turned out to be 130 when it was measured afterwards.
The construction will only survive a few trips into town. Then there is a bang and the car just manages to reach the parking lot of an electronics store. This time, emergency operation is no longer possible. Conclusion:
Running home as punishment and bring tools. The screw is broken, fortunately in a place that is easy to reach with pliers. It is replaced by one from the toolbox for the short drive home. The response rate was even worse.
The few small cables and connectors will have to be replaced later at a cost of almost 100 euros (!).
That's how people are, at least most of them. They have to bang their heads against a lamppost before they take it seriously. Now it's finally time to drive to VW. There you learn that the screw in question may only be
tightened to 8 Nm (!), plus half a turn. Of course, no one usually has a suitable torque wrench for this. But people think they're so clever. At least there is still the screw for the other two injectors. Their torque (after half a turn
= a good 15 Nm) can be determined.
Everything assembled and this time even fitted with a safety device, a kind of crossbar that acts as an additional restraint on the screw. This prevents excessive movement of the injectors in the event of the screw breaking
again and protects the return lines from further damage. Because that's exactly what happened. Why? Because threads can vary, and the half turn is intended to compensate for this.
The mood is at rock bottom. In addition, there was a certain amount of jerking in fifth gear at 80 km/h throughout the entire journey, leading to the assumption of an internal leak in the combustion chambers relative to the
crankcase ventilation. This only improved slightly with the new seals. Now, a set for complete cleaning of the injector shafts prior to installation (picture above) is being purchased.
Of course, you also need a torque wrench that can be set to 8 Nm. But should you opt for a cheap product that may not be calibrated or may be inadequately calibrated? Afterwards, the next screw is lost again. The folks at
VW are already wondering about the strange customer with mostly identical replacement parts. So a quality product (picture above) is purchased with 8 Nm in the middle of the scale, admittedly at an astonishingly low price
on the Internet.
The stuck screw remnant remains, this time broken off further inside. Since attempts to turn it with a steel pin and hammer are unsuccessful, it's off to the local hardware store. However, it only has the screw extractor
shown above. It has to fit the left-hand drill (picture), and I can't order it because it's only available as part of a package. So, back to the internet and waiting.
After a few days, the repair can be continued. Everything is working fine, except that the rubber rings used to seal the cylinder head cover against the injectors are defective. After much searching online, I discovered a set
for replacing the caps clipped into the valve covers. Unfortunately, they are not as secure as the original ones, but they can be sealed with appropriate wrapping.
Was it all worth it? No, it wasn't always fun. And the costs have probably reached workshop level. Maybe people are right after all: 'It's not worth repairing a modern car yourself.'
kfz-tech.de/YDM16
| 
