Piston Hole: Causes and Solutions

Hello,

My TDI (AFN) engine spectacularly failed with a hole in the piston.
disposed of. Oil was burned uncontrollably, and the small engine...
It ran for about 10 seconds at an extremely high speed before I stopped it with the first gear.
Managed to stop the fight from escalating.
The third cylinder has a misfire, and the piston has a 5mm hole.
Hole. During inspection of the nozzles, the third nozzle only had an opening pressure of 175 bar.
But the spray pattern was good.
The vehicle was driven for a while with an increased amount of ESP (but still without the addition of 'Russ').
At the time of the engine failure, there was nothing in the gearbox.
'Now I want to determine the exact cause so that this doesn't happen again. Is the third injector nozzle at fault (the other three pistons show no signs of sticking), or was it actually the extended injection time? If it were the latter, wouldn't all the pistons be affected?'
Have you noticed any damage, such as chipped edges or multiple holes in the piston?
Does anyone have experience distinguishing between a hole caused by a faulty injector nozzle and one caused by over-injection?


Thank you.

Markus.

hi,
I am aware that a hole in a piston of a TDI engine can be caused by a faulty injector. If the opening pressure is too low, it's possible that the injector 'drips' fuel, which can lead to overheating.

Because even with increased fuel injection, it shouldn't happen if there isn't excessive soot production.
Okay, it just provided a little more support for the matter.

Hi,

On the third cylinder is the needle lift actuator . Due to its longer injector needle, it is predisposed to "needle sticking" issues. Consequently, this can lead to damage in the piston area......but wait a moment, let's see what the injection specialists have to say .

haehnlein wrote:

Hi, On the third cylinder, there is a needle lift actuator . Due to its longer injector needle, it is predisposed to "needle sticking" issues. Consequently, this can lead to damage in the piston area......but wait a moment, let's see what the injector specialists have to say

.

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

"Hi,"

I can only agree with my predecessors.
The third injector is the NHG type. This injector is more prone to needle sticking issues and failures (the more parts involved, the higher the chance of failure). These needle sticking events can cause dripping, which creates a diesel puddle that, during the next combustion, forms a hot spot on the piston crown, ultimately damaging the piston over time.

Hello Markus,

My condolences. I have a few questions for you:
- How many kilometers were on your engines when you replaced them?
- What is your typical driving pattern, i.e., mostly short distances, long distances, or a mix of both?
- Have you conducted any experiments with biodiesel/fuel oil or other fuels/food products?

Best regards, Rainer.

Hi,

I also have a question about that.
If the fuel injector is stuck open and therefore dripping fuel, shouldn't...?
Every time the car is started in cold weather, a white cloud appears behind the vehicle as a warning sign.
stand?

Can the opening pressure be measured using an NHG sensor at the nozzle?
'Like with the others, or how do you approach it?'

Achim wrote:

... I also have a question about that. If the fuel injector is stuck open and therefore dripping fuel, shouldn't...? Every time the car is started in cold weather, a white cloud appears behind the vehicle as a warning sign. stand?

Hi Achim,

A cloud of smoke would only form if an extremely large amount of diesel fuel were to drip past the injector. While even a small amount can cause damage to the piston over time, it won't produce a visible plume of smoke. Furthermore, once the engine is turned off, the pressure on the injectors decreases relatively quickly, which prevents excessive dripping.

Quote:

Can the opening pressure be measured using an NHG sensor at the nozzle? Like with the others, or how does one proceed in that case?

Checking the nozzle of the NHG (Natural Gas Heater) works in the same way as checking regular nozzles.

Hello.

Instead of the white exhaust smoke, could reading the idle speed control data using a VAGCOM diagnostic tool potentially provide some clues?

If a nozzle drips and thus introduces "too much" diesel into the cylinder, shouldn't the affected cylinder be throttled back accordingly to compensate for this excess fuel during the idle phase?

It also raises the question of whether the presumed negative value is quantitatively sufficient to be recognized as a warning signal among the usual/normal differences .

Hello Markus,

My condolences. I have a few questions for you:
- How many kilometers were on your engines when you replaced them?
- What is your typical driving pattern, i.e., mostly short distances, long distances, or a mix of both?
- Have you conducted any experiments with biodiesel/fuel oil or other fuels/food products?

Greetings, Rainer.

Hello Rainer,

The injectors had 140,000 km on them, and I drive mostly short distances (about 70%). No modifications were made other than adjusting the fuel injection amount.
It seems to be a rare case. If all the TDI engines fail due to faulty injectors...
such damages would be incurred...
It was probably a combination of a leaky injector nozzle and an excessively long injection duration. The car also sometimes stalled during highway driving, which I now believe was due to a faulty NOx sensor.
Well, the engine will be repaired soon and might get the...
large 0.216 nozzles. I believe in extending the injection time.
Not quite anymore.
Was gibts den für Erfahrungen beim 10cent Tuning? Is there one?
Is there a way to measure the duration of the fuel injection?

Regards,

Markus.

What kind of experiences are there with '10cent tuning'?

It's incredibly fast, and I only turn it on when I really need to overtake quickly. It's off more than 95% of the time, so I don't worry about it much.
by the way: it's still being operated in smoke-free mode.

We recently had a diesel engine with a hole in the piston. In that case as well, the injector nozzle was partially open.

CU Gremlin.

Hello Mrakus.

I had the exact same problem. I was driving on the highway at full speed without a chip, and then suddenly the power cut out, the engine was running at full RPM, and I couldn't turn it off.
Diagnose: Loch im dritten Kolben( Nadelhubgeber). Mein Motor hatte 190Tkm und die hälfte davon mit abschaltbarer Powerbox. Muß jetzt aber dazusagen das mich der Motorschaden nicht gewundert hat, da das Auto seit seiner Geburt nur Vollgas bekommen hat, sogar mit Chip! WI'm a one-liner.

I think the problem was caused by the chip, and consequently, the extended injection time. The injectors weren't old and couldn't possibly have been broken.

I now have an AFN (Activation Frequency Number). And I believe, as you mentioned before, that I have also been healed from the effects of power boxes. If so, then it's a good thing.

Best regards, Golfmann.

Hi, I already discussed this problem half a year ago. I have this strange ticking sound when accelerating lightly, and it seems like it might be coming from the timing chain, but it's hard to pinpoint with all the noise. I also had white smoke before I replaced my injectors.

How can I determine if the NHG nozzle is clogged?

'In my case, when I drive at full throttle on the highway for about two hours, the injector stops clicking for several days. Then it slowly starts to click louder again. The more I drive with partial throttle, the louder the injector gets (up to a certain point, of course).'

If I only buy one new injector now and replace the faulty one, will the ticking noise be gone? Can I leave the other injectors in place, or do I always have to buy a complete set?

The new nozzles have a maximum of 15,000 km on them!

Please help me, thank you.

Okay, and one more thing... Could I possibly tell if the piston is corroded by removing the nozzle and shining a light into it?

Passi_Fire wrote:

Max mileage: 15000 km!

Hi,

That's practically new, right? Or were you thinking of 150,000 km ?

Okay, that's already 15,000 km. Those are the new injectors. And something has been ticking since they were installed.

'It's strange, but I haven't heard it lately... for about two weeks now. Could it be that because it's gotten warmer, the nozzle isn't stuck anymore? I personally can't imagine that, though, because it's already hot enough under the hood.'

other assistance?

'Thank you.'

Deleted upon request.

Hi diesel.gustav,

While I'm not very familiar with the specifics of fuel injectors, a Bosch employee who seemed knowledgeable told me something similar. At least, he said that a stuck needle valve should be unlikely even with 250,000 km (approximately 155,000 miles) on the engine. A stuck needle valve would only be possible in cases of thermal overload of the engine. In such a situation, any driver would quickly notice it due to large clouds of black smoke and poor engine performance, without suffering any further damage.

Now I might get scolded by the "injector experts" , but I think that replacing expensive injectors prematurely doesn't offer much benefit besides a slightly smoother engine run and perhaps a little less smoke. At least, I can hardly imagine that a leaky injector could cause significant damage to the piston. The same applies to theories about piston damage caused by poor spray patterns . There are too many engines with well over 200,000 km still running on their original injectors here in this forum and in practice, and far too few cases of piston damage, which probably have a different cause at the end of the day.

Looking at the statistics, it would probably be better to replace the timing belt more frequently than those overpriced fuel injectors... In most cases, engines fail due to problems with the timing belt.

It's just a suggestion... at least it would be helpful to have more examples .