Turbocharger Hose Wet: Is It Normal on AVF? | Posts 64+

Hello!

"I've noticed something, but I'm not sure if it's related to the starting problem. The hose on the turbocharger (charge air) is very wet, both on the outside and in the area around the turbocharger. It's so wet that the surrounding parts are also damp, such as the air duct from the EGR valve and the wiring harness that runs next to it. I noticed this yesterday using a flashlight and a mirror, as far as I could see from above."
I also have the impression that the turbo whistle has been getting louder sporadically lately .

My question now is: Does the connection piece on the charger have to be 100% dry, or can it be slightly damp, like sometimes happens with the LLK (liquid cooling system)?
I think there might be something wrong with the hose under the heat shield, but it's just a preliminary suspicion for now.

Thank you for your help.

Greetings.

And more news!

Over the weekend, I wanted to check the hose and took a new one with me (just for safety). On Friday, we drove about 150 km. At the destination, I wanted to inspect/check/possibly replace the hose. Unfortunately, we didn't make it that far. The hose had completely ripped on the way there. It was making a hissing sound, which is hard to imagine. It was also smoking, incredibly! I'm glad I already had the new hose. I replaced it in a parking lot, and after 1 hour, we continued. It was running smoothly, without any hissing or whistling. Everything was fine. Unfortunately, the tear in the hose had nothing to do with the starting behavior. And there was also nothing stored in the error memory, which surprised me even more. Because the car was jerking, smoking, and hissing in a way that was frightening. I drove as slowly as possible, using minimal gas, until I reached a place where I could replace the hose. But why there was nothing in the error memory is a mystery to me.

So, my gut feeling was right again.

Greetings.

There was nothing stored in the memory because you drove gently (as you wrote) and the parameters didn't reach the critical range. If you had floored it and continued driving recklessly, the emergency mode would have kicked in and saved the engine.
According to your explanation, you replaced a charge air cooler pipe. That has nothing to do with cold starting; that's normal.

Hi,

Yes, it was the hose right after the turbocharger, the one that connects the turbocharger to the metal pipe. It's actually the "classic" failure point for AVF engines. It eventually happens to every AVF engine manufactured before 2004. I've heard it usually happens around 100,000 km. And indeed, mine now has 98,000 km on it. The new hose is the "improved" version. The rubber compound has been changed. You know why...

The cold start was just a hope, because hope, as they say, dies last. So the search continues .

Greetings.

Hi, it's me again! I have to reach out again because I'm still not making any progress. I have a question about the pre-charge pump, or possibly a "relay clicking" sound that keeps happening after the start-up.

First, regarding the pre-charge pump in the tank:
Sometimes, I don't hear that extremely loud hissing sound (during ignition/startup) from the pump when starting the engine cold and . But: most of the time, it still starts normally. My question: Does the VFP (Variable Fuel Pump) always have to make such a loud hissing sound when starting cold? Or are there situations where it shouldn't/doesn't have to hiss? What would happen if it "fails" while driving?

Now, let's talk about "relay clicking":
"For the first 5 minutes while driving, I repeatedly hear a relatively loud 'clicking' sound coming from the lower left area of the footwell. No, it's NOT the 'clicking' sound of the A/C compressor starting up. It simply clicks during driving, even without any load. I think I heard it click three times at different intervals, and then it stops. What could it be? It can't be the pre-glow system, right? Especially since I start the car cold in the garage where the temperature is 16°C. My guess is that it might be related to the fuel pre-pump. But what happens if the pre-pump isn't running? Would you notice that while driving? If not, could that be an indication of a cold start problem? That could also explain the sporadic 'clicking' during the first 5 minutes. Could someone please tell me if that's possible? Again: once the engine is running, there are absolutely no problems, no hesitation or anything else. It runs perfectly."

Danke für die ev. Help.

Greetings

Mike3BG wrote:

...Therefore, also the occasional "clicking" sound in the first 5 minutes. Could someone please tell me if that is normal?

Hi Mike,

The clicking sound within the first few minutes after starting is 99% likely the relay that controls the glow plugs. The engine continues to glow after the start. The colder the coolant was at the start, the longer it will continue to glow. You can probably find information about this in technical articles as well. The glow function is temporarily interrupted if the engine speed exceeds 2500 RPM, if you want to subject your cold engine to that.

Just try pulling out the glow plug relay and listen to see if you still hear the clicking sound.

Regarding the other points, I have nothing to say.

Regards,
Guste.

Thanks for the information. A VW mechanic said exactly the same thing yesterday. It seems this is really caused by afterglow.

Regarding the pre-charge pump, he told me that it doesn't always have to hiss. It also depends on the idle time and temperature. If the pressure is sufficient or the line is full, it won't hiss. And if the pump fails during driving, the car supposedly stops. They once had a Sharan that exhibited this behavior.
So, there aren't really any well-founded conclusions that can be drawn here.

I'm really starting to not know what to do anymore. Apparently, no one has ever encountered an error like this before. Maybe my can lend me an engine control unit (ECU) temporarily to rule it out.

Air in the system can probably be ruled out, because there was a time when it started normally, but I only drove 20 meters. Then I stopped and waited for 5 minutes. Then I started it again, and it threw the error. So, it's really unlikely that air would get into the system within 5 minutes, right?

Greetings.

I have an audio file (recorded with my phone) for the first time, regarding the starting problem. It's a NOKIA file (*.amr). Can anyone listen to it to see if it helps? How do I upload it here?

Sure, here's the translation:

"thx"

Regards,

EDIT: One less potential source of error: it's not the relay for the engine control unit (ECU) either. The error persists and now occurs more frequently and lasts longer in case of a fault. It would be great if someone could give me tips on which values I can log with VAG-COM in case of an error, in order to potentially rule out other things. If I'm holding the ignition key for 4 seconds or longer, shouldn't something be logged, right?

Somehow, I'm increasingly feeling that it's the engine control unit (ECU) itself.

Hello!

Leute, laßt mich bitte keine Selbstgespräche führen. Hat keiner mehr Tips? Ich habe weitere echt interessante Neuigkeiten, mit denen ihr vielleicht was anfangen könnt. Heute Mittag habe ich erstmalig was wichtiges testen können. Und Sure, here's the translation:

"Sure, here it is:"

Cold start, approximately 12°C: As usual in case of an error, it cranked for about 4 seconds, then it started. I then turned it off again to see if it might not start again immediately. And sure enough, it did it again (it cranked, with ignition sounds), but only for about 2 seconds, then it ran normally. I wanted to try that a third time. And sure enough, it worked a third time, but again for a shorter duration, about 1 second, then it ran normally.

Okay everyone, what do you think about this? It can't be air in the fuel system, right? Never, or what? What exactly changes in those few seconds within the engine that causes the fault to occur less and less frequently, until it eventually disappears altogether? After that, I could have started it a thousand times, and it would have started 100% every time, even when it's still cold.

Could this be related to the shut-off valve? For example, could the shut-off valve be momentarily activated during the starting process?

Does anyone have any other tips?

Thank you.

Greetings.

The starter motor is also not .
"The pre-lift pump isn't working, and I've disconnected it for testing, but the car still shuts off after a few kilometers and won't start again. Even after replacing the fuse, it doesn't start for a long time. I'm completely stuck and don't know what to do anymore... I'm starting to despair."

Mike3BG wrote:

The pre-lift pump, which is used for testing, is not working either, because the car shuts off after a few kilometers and won't start again. Even if you put the fuse back in, it doesn't start for a long time. I don't know what to do anymore... I'm desperate.

Okay, looking at this in isolation, my opinion is that it indicates an air leak somewhere in the diesel fuel line between the tank and the engine. Without the pressure from the fuel pre-pump, air is being drawn in, which accumulates in the fuel filter, and the filter needs to be properly bled before the next start -> resulting in the "orgel orgel" sound.
It's possible that air could also enter the primary circuit while the system is idle, and (depending on the thermal expansion of the area around the leak), this could cause starting problems.

I don't have time to re-read the entire thread right now. But if you haven't already installed a clear section of tubing in the inlet line between the differential pressure sensor (DiFi) and the pump, I would do that now. Then, during the next startups (ideally with someone assisting), pay close attention to any continuous air bubbles.

Hello Ulf!

The tip is really good! Because it shouldn't be normal for it to shut off without a pre-pump and then not start for a long time because of air inside. Only after being towed (with a very steep angle during loading and unloading) did it start with the starter motor (but normal cranking without any ignition sound!!!!), and then it ran normally again. But why was there such an extreme "air pocket" inside that was almost impossible to bleed automatically? Maybe due to a leak, that's possible. Unfortunately, you can't see anything with the naked eye! Nothing is wet or damp, except for a slight amount near the tandem pump. There is already some oily residue on the side of the tandem pump, but supposedly that shouldn't cause any problems.

Okay, your theory about the air is really good, but there's one thing that contradicts it. Why, even after it starts, does the problem (as described above, my new observation) still occur when you turn it off and immediately restart it, but the problem occurs for a shorter duration each time? Then, a third time, the problem occurs for an even shorter duration, and then it doesn't occur at all, even if you start and turn it off 1000 times. In other words, the problem gradually gets shorter until it disappears completely. The first attempt involved about 4 seconds of cranking with ignition sounds, then it was turned off, restarted, and then it cranked for about 2 seconds with ignition sounds. After turning it off again, it cranked for about 1 second, and then I could have started it 1000 times in a row without any problems. It seems unlikely that air could accumulate so quickly in the short time that the engine is running before you turn it off and restart it, right? The fuel pump seems to be working normally; it's making its "whistling" sound, so it's building pressure, but the engine still hesitates when starting.

Thanks again for the tips.

Greetings.

Mike3BG wrote:

Why is the error (as described above on this page, my new observation) still present, even when, after it starts, it turns off and restarts immediately, and the error occurs again, but only for a shorter duration? Then, a third time, the error occurs again, but only for a very short time. After that, it no longer occurs, even if you were to start and turn off 1000 times. In other words, the error gradually becomes shorter, until it no longer occurs at all.

Perhaps the air is not immediately completely flushed out of the critical area during the short engine run, but is instead partially pushed into "harmless corners," from which residues can spread again and hinder restarting when the engine is stationary?

Air leaks don't necessarily have to be visibly oily or damp on the outside -> we've seen this happen multiple times here in the forum.

If I were in your place, I would replace or bypass the entire diesel pre-filter with a temporary solution using a single piece of clear tubing, as much as possible. Perhaps you will find the missing parts of the fuel system in the process.

Hi Ulf!

Okay, in order to completely rule this out, I will take action regarding this. However, I'm not brave enough to tackle the hose issue. Firstly, I don't know which hose to use for that, and secondly, I don't have time for such intensive activities in the near future. My thought is: would it make sense to have someone "disconnect" the line from the on the tank (the fittings at the pre-pump) all the way to the tandem pump. There must be something like that, even according to VW's specifications, if I remember correctly.

So, you also believe that the PD (positive displacement pump) should not draw in air, even if the pre-pump is not running, and that it should build up a pressure cushion in the system, making it very difficult to start up afterwards, right?
Who is right? Some people say: "The PD (presumably a type of engine) runs even without a pre-pump; it's only there for starting." Others say: "The PD will shut off and not run without a pre-pump!"
Some PDs have absolutely no VFP! The first PDs definitely didn't have any.

My realization:
"However, I was able to drive about 4km in the city without the pump. Then I got onto the highway, pressed the accelerator a bit harder, and it started to stutter and then completely stalled. It wouldn't start again, even though the fuel pump was running. You could hear it "gurgling" each time, but it didn't help! It only started again after I unloaded and reloaded everything. It was very rough at first, but then it ran normally."

What do you think about the case? Are you sticking to your opinion?

Greetings.

Hello Ulf and Co.

Mein hat mir auf meinen (deinen) Tip hinauf 2 durchsichtige kurze Stücke Kraftstoffschläuche eingebaut. Er hats so gemacht: Gleich nach dem Dieselfilter in den Vor- und Rücklauf gekürzte orig. Schläuche vom AFN genommen. Einen leichten Bogen nach oben, damit sind die durchsichtigen Stücke der höchste Punkt zwischen Filter und Tandempumpe. Jetzt werden wir mal beobachten ob und wieviel sich da an ev. Luft accumulates.
What surprises both of us is why the problem has improved since the pipeline between the pre-feed pump and the PDs was emptied. And I'm certainly not imagining that. It's been easier since then. But why? What could have changed in this process?

Greetings.

Hello everyone!

Kurzer Zwischenbericht: Ich fahr ja jetzt schon 2 Wochen mit den durchsichtigen Schläuchen nach dem Kraftstoffilter, und abgenommener Motorabdeckung herum. Gleichzeitig wurde damals die Tandempumpe mittels Druckgerät überprüft. 2 mal sogar, einmal im warmen und einmal im kalten Zustand, allerdings ohne Befund, alles bestens! Was soll ich sagen? Seit dieser "Aktion" ist das Auto nicht EINMAL schlecht angesprungen !!!!! Das kann doch kein Zufall sein, wenn es vorher mind. 2 mal am Tag aufgetreten ist. Hat jemand eine logische Erklärung dafür? Die durchsichtigen Schläuche haben daher bis jetzt keine Aufschlüsse geben können (Blasenbildung oder dgl. NICHT vorhanden) weil er seit dem ja perfekt anspringt. Nur why?

Greetings.