W204 OM646 Injector Leak

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B0bby92
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Attached you can see a video of my W204 with OM646.811 engine. I have a big problem with leaky injectors. Injector seats are cleaned, seals are replaced, and injectors are completely overhauled.
New quantity control valve.
The pressure regulator in the rail is new.
The pressure sensor in the rail is new.
Xentry scan revealed no engine faults.
What could be the problem?
 
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Sorry if this is a stupid question, but have you checked the overflow tubes?
And how many kilometers does it take for the injectors to leak enough diesel fuel to be visible to the naked eye after cleaning them?
 
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What was the purpose of an injector overhaul? When they start leaking on an OM646 engine, it is mostly due to broken seals. Carbon then builds up which can be seen as a black residue, commonly referred to as black death. Typically the injectors need to be pulled and cleaned, the seals replaced, the seats cleaned with the proper tools and the screws/holders replaced – that’s it.

Now, what I see in your video is a leak on EVERY injector (including bubbles), which is highly unlikely after a complete rebuild. My guess is that someone made a mistake during assembly:

  • Wrong injectors
  • Wrong seals
  • Too long screws / screw holes not cleaned enough
  • Wrong injector holders or the screws are not fully screwed in (see above)
  • Extreme abrasive injector seat clean up and destruction of cylinder head

Anything higher up, like fuel lines, is unlikely as we see bubbles rising.
Have you double checked everything?
 
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Forgot to mention that these tubes are also new. You drive 1-2 km, and they look like in the video. Sometimes they do not leak at idle.
 
What was the purpose of an injector overhaul? When they start leaking on an OM646 engine, it is mostly due to broken seals. Carbon then builds up which can be seen as a black residue, commonly referred to as black death. Typically the injectors need to be pulled and cleaned, the seals replaced, the seats cleaned with the proper tools and the screws/holders replaced – that’s it.

Now, what I see in your video is a leak on EVERY injector (including bubbles), which is highly unlikely after a complete rebuild. My guess is that someone made a mistake during assembly:

  • Wrong injectors
  • Wrong seals
  • Too long screws / screw holes not cleaned enough
  • Wrong injector holders or the screws are not fully screwed in (see above)
  • Extreme abrasive injector seat clean up and destruction of cylinder head

Anything higher up, like fuel lines, is unlikely as we see bubbles rising.
Have you double checked everything?

We have already done this procedure 3-4 times. Yesterday we even resealed the second injector with a new seal because of these bubbles, and now it is better, but after a short trip all the beds are filled with diesel fuel again. They do not fill up at idle. They are all very well cleaned, the seats are cleaned with a special cutting tool. Each injector is in its place. We use new original bolts for each manipulation. We tried original seals and Bosch seals, which are a little thicker, but the result was the same. Even two bolts had a problem with the thread, and the mechanic made a new one. They are tightened correctly, as specified in the catalog - 7 Nm +90 +90. I really do not understand what could have caused this leak. Maybe excess pressure during acceleration? I cannot perform a quantity calibration with Xentry for an unknown reason, even after meeting all the conditions, but this is a separate topic.
 
If possible, go to a garage with a lift, put the car on the lift, turn off the Traction Control/ESP, then slowly give the gas to 3000 rpm and check. You should find the leak immediately because the problem repeats after only 1-2 km. I believe this is the best method at this stage. The technician can sit on the hood latch holder for a more detailed inspection.

You can try the same method if you have jack stands, just be careful not to press the gas pedal too hard, if the car is only on jack stands, just accelerate and decelerate slowly, and again remember to turn off the Traction Control/ESP.
 
Let's try to understand each other. How many km does the car have? Agree that Xentry does not detect problems. But if the car has a high mileage, then there may be deposits inside the chamber, due to which the injectors pass back.
 
The car's mileage is 355 thousand km.
 
Let's try to understand each other. How many km does the car have? Agree that Xentry does not detect problems. But if the car has a high mileage, then there may be deposits inside the chamber, due to which the injectors pass back.

He described the injectors as being completely rebuilt, I'm guessing they were taken apart and thoroughly cleaned before reassembling the injectors so there was no chance of deposits. Even if there were deposits, I don't think the injector could throw fuel back with enough force to cause that much fuel leakage without the engine misfiring.
 
Could a bad O2 sensor be the cause of this leak and higher pressure? Today the check engine light came on and I saw this O2 sensor error using Xentry: 23E2-015 Check component G3/2 (Oxygen sensor upstream of catalytic converter).
CURRENT and STORED.
 

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