Luftblasen im Diesel, Tankanlage defekt? | Posts 16+

Is that your log or mine?
In my first log, there's a draft test included, although it only involves 2 people, but that doesn't matter.

Was ist das? Is that chart created using Excel, or what? What measurement unit did you use?
The previous owner of the new TDi may have already cleaned the mass airflow sensor (MAF) because VW was trying to sell them one. He had only replaced the solenoid valve, but that thing was really defective .

Otherwise, you would have to invest 75 euros. Because I think that 1-second difference between the two cars is a lot. The climate doesn't really make that much of a difference in terms of weight, and even with 16-inch wheels, the older model was slightly faster than the new one.

It would be strange if the LMM (likely referring to a lambda sensor or similar) were actually faulty, because in that case, it should still spin up cleanly to 4500 RPM.

Okay, so I replaced the check valve the evening before my vacation trip.
It seems like the excitement has died down. But despite the polished car (better aerodynamics ).
"And if there's no air in the diesel line, the engine's performance won't be quite right."
It's slightly faster in the DZT mode, but that could also be due to measurement tolerances and less fuel in the tank, accounting for the 0.3 seconds, even though it was 28°C yesterday. However, 9.1 seconds still seems quite high for a 90 horsepower TDI in a Golf 3. Moreover, in DZT mode, the turbo boost that is noticeable at 1500 rpm, as was the case with the older 1Z engine, is not felt. Or is that due to a faulty EGR valve?

Hello everyone!

I'm almost at my wit's end. I'm also experiencing air bubbles in the clear fuel line on my ALH (Audi A3, manufactured in 03/1999, 1.9TDI ALH). It's particularly noticeable when accelerating from a standstill at higher RPMs; it really sucks in a lot of air.
When the engine is turned off, you can see air bubbles traveling from the injection pump to the highest point of the line (a transparent hose) connecting the fuel filter to the injection pump. The amount of air bubbles present when the engine is off is approximately 0.5 to 4 centimeters. The average is 1 cm.
Since I'm a diligent reader, I've already replaced the diesel filter, the valve on the diesel filter, and the hoses from the diesel filter to the injection pump (using replacement parts). I 'sealed' all the connections with screw-type hose clamps. That helped for exactly 2 days. After that, I experienced the same problem as before.
Just to let you know, there's a T-piece with a check valve connecting the new hose set to the diesel filter, which is for the auxiliary heater. However, it was disconnected for the test and had no effect.
I'm really at a loss. Oh, and opening the fuel cap doesn't make any difference. And if you tap the filter with your fist, the bubbles get bigger.

Perhaps someone else has an idea about my problem. The car starts a little worse because of it. Furthermore, the air bubbles are bad for the auxiliary heating system.

Sure, no problem!

Regards,
Christof.

Can anyone help me with this?

Does anyone have any information about the fuel tank system in the Audi A3 8L TDI (ALH) model?

@Chris:

This air bubble is normal, and up to 1cm is usually acceptable. I had the same issue with my Golf 4 ALH, and it ran perfectly fine with it. Even though my SH (presumably a device) was also connected to the main line, it had no effect on that air bubble.

-> Search function: Power loss.

According to HST, the formation of air bubbles in all parts of the fuel line is normal if BD (presumably a type of fuel) was added, even without a leak.

Roger wrote:

According to HST, the formation of air bubbles in all parts of the fuel line without a leak is normal when BD has been refueled.

Who or what is HST? *blank stare*

Service and Maintenance Manual.
Every customer-facing employee has access to the WinElsa program, specifically the "Technical Problem Solving" section. However, they are not officially allowed to show this to customers or third parties.

Sorry, Ulf.

Just ignore me, and nothing else will happen in your brain.

chrisgtd1 wrote:

I'm also having the problem with air in the supply line. but the fact that the diesel engine runs on air is unclear. "As the name suggests, fuel provides power, right?" and air, nothing. Bitte gib den Text an, den du übersetzt haben möchtest. I experience this problem at speeds of approximately 140 to 180 km/h, so only in engine speed ranges above... 2500 to 4300 /min, but if less fuel is injected, there's less power, which leads to a reduction in boost pressure, meaning no more "smoke" or am I wrong?

Okay, I won't be helping you with this constant writing style anymore, because reading it gives me severe brain cramps -> Another blunder, number 8 .

Aloha everyone!
Attention, forum archaeology! But this is probably the most suitable place for me to chime in...
The general problem is the same as before, and my specific issue is that I can't seem to close the VWV (presumably a valve or fitting) with the sealing ring underneath without using force. Is it absolutely necessary to modify something to make it fit? Or did I receive the wrong sealing ring, part number N 904 264 02?
I first tried to get the sealing ring under the old valve, because there wasn't one there , before I replace the valve and start messing around with the hoses.

Best regards,
Torsten.

Edit: I only noticed later, in the dim light of the lamp, that there's a thin sealing ring around the flange on the fuel injector. But is the purchased O-ring supposed to go there? Today I installed the new VWV, and there are still some air bubbles, even though I refilled the fuel injector. There's quite a bit that supports flightmasters' point of view. Right now, I can't really do anything, so I'll just observe what happens over the next few days and see what happens when it gets warm again.

Golf 4, ALH engine, 190,000 km, all original, first ESP (Electronic Stability Program) and injectors.

Hello everyone,

I'd like to share my perspective on this topic.

The air bubbles in the supply line are as old as the 'return valve' itself.

After years of searching and 'experimenting,' I've come to the conclusion that the preheating system via the return valve is a design flaw. Proper self-venting is no longer occurring.

As soon as any air enters the system, it accumulates in the filter, causing the fuel level to drop, and eventually, air will appear in the fuel line.

I once replaced all the hoses before and after the filter with clear ones. It was observed that the diesel fuel entered the filter without air, but then produced bubbles.

However, this only happened when the engine had been running for a while. When the engine was cold, and the preheating valve was injecting diesel into the filter, there was never any air visible. When the valve opens, allowing full vacuum to act on the filter, air appears after the filter. Experiments involving filters without a check valve, complete filter filling, and direct discharge into the tank, as well as sealing the check valve on the original filter with silicone, were all unsuccessful.

The amount of air bubbles formed is directly related to how cold the fuel is. The viscosity of the diesel affects the vacuum in the filter, and thus the formation of air bubbles. Therefore, this phenomenon is more pronounced with RME than with conventional diesel, but only when the preheating valve directly feeds the diesel into the tank. No air is visible during the preheating process.

A proper solution would only be achieved with a pre-feed pump that continuously reduces the vacuum in the filter, thereby ensuring proper venting.

Sure, here's the translation:

'MFG' is an abbreviation for 'Mit freundlichen Grüßen,' which translates to 'Sincerely' or 'Best regards' in English.

AhA!
Sure, here is the translation of the text from German to English:

"Please see my edit above."
Is there a way to customize it with original parts? Can anyone offer some advice? Perhaps there is a related model, AFN?

Best regards,
Torsten.

Hello Enzo,

I gave up on it at some point. According to the VW repair manual, the fuel sensor should be replaced in cases like this.
Unfortunately, I don't know the internal structure, but it might be worth trying.

I once took mine apart, but I didn't completely disassemble it. There is a filter screen located inside the housing.
If this is not properly vented, the Dino's tendency to produce a lot of foam, combined with the VP37's high pumping capacity, could cause gas bubbles to form in the tank and be drawn into the system.

I've given up on the search.
As the only modification I made, I installed a check valve before the filter, and I replaced all the hose clamps with hose clamps that tighten with a screwdriver. I also replaced the preheating valve at one point.
Air bubbles are still visible.

Please share your results...

Sure, here's the translation:

'MFG' is an abbreviation for 'Mit freundlichen Grüßen,' which translates to 'Sincerely' or 'Best regards' in English.

Aloha, flightmaster!
Okay, that's a starting point. How much does that thing cost? I'll search online now, but it might be a fruitless effort, since it's probably a special VW part, right? Maybe I'll find someone who can install it for me at a reasonable price; it depends on the total cost.
I think you shouldn't be too stingy in this case, because it's certainly not really healthy for the pump in the long run, even if it's a VP37. A few bubbles here and there are okay, but if you're sucking in foam (I had quite a lot of it at times) and if you're even experiencing engine cutouts (twice sporadically on the road), you need to do something. Or?

But the question of OTP (OriginalTeilePimping ) remains.

Best regards,
Torsten.

Hi Enzo,

'So, hearing things like sputtering in the intake or engine misfires doesn't sound good. How old is the filter?' If the input is saturated, for example, due to RME (Radio-Frequency Modulation Emulation), then these exact problems occur.

You might want to check the lines before you start replacing a lot of parts.

Sure, here's the translation:

'MFG' is an abbreviation for 'Mit freundlichen Grüßen,' which translates to 'Sincerely' or 'Best regards' in English.