Identifying worn camshafts in V6 TDI engines

This week, I had the pleasure of replacing worn camshafts in a V6 TDI engine (engine code: AKE), and I made the following observation:

Ich hab genau diesen Motor schon oft vor der Reperatur gefahren. Dabei ist mir schon immer im Vergleich zu anderen V6 TDI´s (gleicher und andere MKB, 150-180PS), aufgefallen das dieser eine geringere Öltemperatur, in allen betriebssituationen erreichte. Ich hab mir dabei bisher nix gedacht. Ich dachte vielleicht hat der einen besseren Ölkühler oder so. HiePlease provide the values.

"Mentioned V6 TDI engine (with faulty glow plug)."
Normal driving: Oil temperature of 70-80 degrees Celsius.
Fast driving: 80-95 degrees Celsius oil temperature (never above 95 degrees, returns to below 80 degrees after approximately 1 km of normal driving).

Other V6 TDI engines (that did not have faulty glow plugs):
Normal driving: Oil temperature 85-95 degrees Celsius.
Fast driving: Oil temperature 95-110 degrees Celsius (after approximately 3 km of normal driving, returns to 95 degrees).


After replacing the camshafts, the engine immediately exhibited the same oil temperature behavior as other V6 TDI engines during the test drive. It was no longer showing 75 degrees Celsius like before. The oil temperature quickly rose to 90 degrees Celsius, even with very gentle driving! With that kind of driving, the oil temperature had not exceeded 70 degrees Celsius before the repair.


Es scheint also einen deutlichen zusammenhang zwischen der Öltemperatur und dem Zustand der Nockenwellen zu geben. Die Ermittlung der genanten Werte erfolgte bei ähnlichen als auch bei verschiedenen Umgebungsbedingungen. Das Ergebniss war aber immer annährend gleich. Es handelt sich um gemittelte durchschnittswerte. Die Nockenwellen des Testfahrzeugs waren auch nicht Übermäßig verschlissen. Maximal 2mm pro Nocken, manche Nocken hatten auch gar keine Verschleisserscheinungen (z.B. genau die zwei unterm Öleinfüllstutzen ). Leistung hat auch nicht groß gefehlt. VerbrIt was also normal, and with a range from 8.5 to 12 liters (for models with Quattro, manual transmission, and Allroad), anything was possible.


P.S. I would really appreciate it if an administrator or one of the moderators could look into this and move it to the error/knowledge base as an article.

"I would do that, but unfortunately, mine runs just below 80°C with both the old and new cooling systems, even under light or moderate load. It only got really hot once when I was pulling a heavy trailer in temperatures above 30°C in the shade."

christians wrote:

I would do that, but unfortunately, mine runs just below 80°C with both the old and new cooling systems, even under light or moderate load. It only got really high once when I was pulling a heavy trailer in temperatures above 30°C in the shade.

Perhaps it doesn't seem as significant with the AKN simply because it is subjected to less thermal stress due to its lower power output .

The temperatures at low load should be the same for all engines, as neither 150 nor 180 horsepower are being demanded in those conditions.
I can't explain that. When the Northwest (NW) module was replaced, was anything else swapped out or adjusted?

christians wrote:

I can't explain that. When the NW was replaced, was anything else exchanged or adjusted?

To be honest, I can't really explain it, even from a purely technical standpoint. Otherwise, nothing else was swapped or adjusted. So, it must be related to the camshafts.

Hello everyone,

Thinking about it, there might be something to it. My automatic transmission used to have a tendency for lower oil temperatures even before the repair. Yesterday, on a longer drive on the highway, I could also read an oil temperature of around 90-100°C at ~130 km/h. It was definitely lower before because I always check the oil temperature before giving the car its full power.

VG

TDI-GTI-4-Motion wrote:

After replacing the camshafts, the engine immediately exhibited the same oil temperature behavior as other V6 TDI engines during the test drive. It was no longer showing 75 degrees Celsius like before. The oil temperature quickly rose to 90 degrees Celsius, even with very gentle driving! With that kind of driving, the oil temperature had not exceeded 70 degrees Celsius before the repair. It appears there is a clear correlation between the oil temperature and the condition of the camshafts. P.S. Würd mich sehr freuen wenn der Admin oder einer der Moderatoren sich der sache mal annehmen würde und das ganze als Artikel in die Fehler-/Wissensdatenbank verschieben würde.

Error: Knowledge/Database.

According to your theory, if I install the old shaft in a new engine, the oil temperature should decrease... If that's correct, it might be possible to determine the relationship between oil temperature and camshaft wear using technical chart analysis.
Oder ist die Kennline, immer wenn ich Nockenwellen tausche steigt danach die Öltemp.
And that's with a special motor with that power output...
I think the engine isn't in its original condition after the camshaft was installed.

scroll tdi wrote:

Error: Knowledge/Database. According to your theory, if I install the old shaft in a new engine, the oil temperature should decrease... If that's correct, it might be possible to determine the relationship between oil temperature and camshaft wear using technical chart analysis. Oder ist die Kennline, immer wenn ich Nockenwellen tausche steigt danach die Öltemp. And that's with a special motor with that power output... Denke der Motor hat nach dem Einbau der Nockenwelle nicht den Urzustand..

I've simply written down my observation. The person who spoke before you also confirmed this observation. So, it seems there's something to it.

I've already realized that nobody really believes me about this. The best thing to do is to delete it all and not think about it anymore. } It's a shame, I just wanted to help.

Hello,

I think the observed effect is likely due to random chance. Why should the oil temperature be different with other camshafts?

The only reason for low oil temperatures would be an extremely reduced air mass (and thus fuel injection volume) due to significantly worn camshafts at full throttle.
If there is a prolonged lack of gas, the situation could even be the opposite, as a reduced airflow can also cause the engine to cool down more slowly.

However, the outside temperature likely has almost as much of an influence, provided the car is still running.

Best regards, Rainer.

Quote:

Einziger Grund, für niedrige Öltemperaturen wäre extrem verringerte Luftmasse (und damit Einspritzmenge) durch ziemlich abgenutzte Nocken bei Vollgas.

I also believe that these scavenging losses are the main cause, because the desired filling level cannot be achieved at high speeds and loads. There may even be residual exhaust gases remaining in the combustion chamber during combustion.

TDI-GTI-4-Motion wrote:

The oil temperature rose quite quickly to 90 degrees, even with a very gentle driving style! With that kind of driving, it didn't exceed 70 degrees oil temperature before the repair.

The core issue lies in the understanding of how it works. With that type of driving behavior, a faulty EGR valve is more likely to be detected by observing the EGR timing ratio rather than the oil temperature. The engine control unit (ECU) doesn't differentiate between internal and external EGR, as it only monitors the air mass.

Furthermore, I didn't say that I don't accept your observation; I certainly believe it. However, I have a problem with the conclusion you draw from it.

BM wrote:

Quote: Einziger Grund, für niedrige Öltemperaturen wäre extrem verringerte Luftmasse (und damit Einspritzmenge) durch ziemlich abgenutzte Nocken bei Vollgas. I also think that these scavenging losses are the main cause, because the desired filling level cannot be achieved at high speeds and loads. Possibly, there are even residual exhaust gases remaining in the combustion chamber during combustion.

That could be the key issue. Due to the poorer cylinder filling, caused by the reduced valve lift, the compression temperature also decreases.
And that value is typically between 600c and 900c for diesel engines. As the engine speed increases, the volumetric efficiency decreases further, which can potentially reduce the thermal load on the engine.

It is also possible that it's all a load of nonsense.