Audi 3.0 TDI CDUC Piston Endoscopic Inspection

Hello, I removed my injectors yesterday to have them checked, as well as...
I looked into the combustion chamber with my endoscope camera.
Now I have 3 questions that remain unanswered.

Why do some pistons on the top side have no carbon deposits? (Image 5, 6)

2) Are the carbon deposits on the piston crown and cylinder wall normal, or are they harmful? (Images 1, 2, 3, 4, 7)

3) What do you say about the scratch marks on the cylinder wall? (See images 8 and 9).

The Audi was manufactured in 2014 and currently has almost 89,000 kilometers (approximately 55,000 miles) on the odometer.
I hope you can help me; thank you in advance.

Soot or lack thereof can be caused by differently functioning injectors...

The marks could be caused by moisture in the cylinder after a period of inactivity.

What are your oil change intervals?

Do you use branded or generic diesel fuel?

Hello, thank you for your reply. Since I bought the car, about 10,000 km ago, I've mostly been using regular diesel at a Shell gas station.

I've now changed the oil change interval to a fixed interval of every 10,000 km. Previously, the car was serviced at Audi using the longlife interval.

And yes, the Audi is a summer vehicle, which means it will be idle for longer periods more often during the winter!

Hi there,
Is there a problem with the vehicle?
hg
Herbert.

"No, there are no problems with the car. I just wanted to have the injectors checked and hear your opinions on whether anything looks problematic."

It's impossible to avoid marks inside the cylinder. The best approach is to run the engine thoroughly hot before storing it for the winter and then turning it off, avoiding any further use in between.

When my father used to winterize the Claas Columbus combine harvester, he would insert oily rags into the exhaust pipe and the air filter connection.

I would now remove the glow plugs, verschandeln them, and reinstall them with ceramic paste on the threads, possibly replacing them if necessary. Be sure to observe the specified torque when tightening.

Hi there,
Using VCDS, it is standard practice to first check the engine running hours and then examine any deviations in the injector timing.
If everything is normal, you generally don't do anything else, unless you have too much time and money.

Herbert.

Thank you for your answers.

Actually, my intention was only to replace the copper sealing rings of the injectors, as these tend to fail and leak in engines. So, I also sent the injectors for inspection and had an endoscopic examination performed.

So, you're saying that these small deposits of soot, as seen in images 1, 2, 3, and 4, don't pose a significant problem?

It is important to carefully verschandeln the area where the burner nozzles are located.

In my opinion, soot from diesel engines is normal.

Quote:

My intention was actually just to replace the copper sealing rings of the injectors, because they tend to fail and leak in engines.

Sind bei mir nach 170000 km immer noch dicht. Meaningless action.
hg
Herbert.

"Leaks sometimes occur in the V6 engines."

Let's do everything right this time and enjoy peace for the next 5 to 10 years.

vicky66 wrote:

Thank you for your answers. My intention was simply to replace the copper sealing rings of the injectors, as they tend to fail and leak in these engines. Therefore, I also sent the injectors for inspection and had an endoscopic examination performed. Also meint ihr diese Rußhäufchen wie auf Bild 1,2,3,4 zu sehen stellen auch kein großes Problem da ?

It makes no sense to remove injectors that are in good condition and functioning properly.

"IF an injector seal was leaking, I would only address that specific cylinder. For the rest, I would check if everything is sealed properly (which depends on the design of the cylinder head to see if that's easily possible) or verify the torque of the injector hold-downs."

Tight fit = no problem with the sealing ring.

Die Cu-Dichtringe gehen auch nicht "einfach so" kaputt, sondern weil der Injektor nicht richtig an den ZK gepresst wird, ergo der Halter nicht fest ist.

Best regards, Rainer.

Okay, thank you. However, I have one more question: What is the best way to identify a leaking injector?

You'll notice it with starting difficulties when the rail pressure is low. Otherwise, the next day after stopping the engine, you can use an endoscope to check if the injector and combustion chamber are wet by drilling a hole in the glow plug housing.

Regarding the issue of leaking fuel injectors, we once had a company-owned Mercedes-Benz Vito 108 CDI with less than 100,000 kilometers on the odometer, and all of its fuel injectors were leaking.

Rüdi wrote:

You'll notice it with starting difficulties when the rail pressure is low. Otherwise, you can check the next day after stopping the engine by drilling a hole in the glow plug and using an endoscope to see if the injector and combustion chamber are wet.

Neither of those options seems sensible.
The first signs would be irregularities in the engine's running and a pungent smell from the exhaust.
During a systematic inspection, one examines the flow stability, switching time variations, return flow rates, and, if there is suspicion of a leaking nozzle, the pressure drop.
Can we finalize it then?
Herbert.