I have a problem with the engine. When driving at low RPM, oil doesn't get pushed into the air hoses, but once you rev up the engine, after about 10 km, it manages to push around 1 liter of oil into the air hoses. The turbos are new, original, so the problem is not there. The engine runs perfectly fine without any strange noises or issues. I suspect the crankcase ventilation, but I don’t know what could be causing this problem, especially since I also have a new separator. Has anyone encountered a similar issue? Thank you all for your valuable advice.

There is a valve in the bottom of the oil filter housing attached to a spring steel clip which has been known to become dislodged which then allows oil to drain to the breather oil separator which then pushes oil out the breather into the inlet tract. I suggest that the oil filter be removed and the valve and spring clip inspected in case it has been dislodged or if the rubber plug has gone. A forum member is selling the plugs, possibly listed as being for the L322 but they're for the 4.4 TDV8/SDV8.

Alright, do you think that fixing this will stop the oil from getting into the hoses? It seems to me like there’s pressure in the engine, but the crankcase ventilation is clogged. The reason I think so is that I have oil leaking from the crankshaft seal. What you mentioned sounds like the vent is open, but it should be closed. I don’t fully understand how the ventilation works on this engine, as it seems to me that the system is too complex with the vacuum being created in the EGR valve. That’s why I’m asking if it could be blocked somewhere. Thank you.

Are there any photos of this at all? Got - 2017 SDV8 Autobiography in Loire Blue
Had- 2008 TDV8 Vogue SE in Java black
Had - 2007 S/C in Stornoway Grey

Oil filter housing drain...

https://www.fullfatrr.com/forum/topic67698...lter+drain

Radek:
Maybe the breather hose is overloaded with oil from the filter housing or maybe there's another cause but it is very easy to check the drain valve.
The filter keeps pressure on the spring when the cover is screwed down but when the cover is unscrewed a few threads the filter is pushed up by the spring which then allows the oil in the housing to drain to reduce oil in the filter when it is removed, assuming that the spring is in place and the plug is still fitted.

Great, thanks a million  Got - 2017 SDV8 Autobiography in Loire Blue
Had- 2008 TDV8 Vogue SE in Java black
Had - 2007 S/C in Stornoway Grey

So I removed the oil filter, and the spring is in place. The plastic clip is also there. Does anyone have any other ideas about what could be causing the oil to be in the air intake hoses? I’m really frustrated, and no one seems to know what’s going on. I was thinking maybe the whole EGR system is faulty since the crankcase ventilation is connected. Thank you.

Crankcase ventilation doesn't have anything to do with EGR other than the separator appearing to be located below or close by to the EGR cooler.

Has the oil been drained and measured or refilled with the correct quantity to ensure that the sump hasn't been overfilled? The oil level sensor isn't 100% reliable so always fill only the correct quantity of oil.

I'll put it this way: my engine was completely rebuilt, with new turbos, DPF filter, injectors—basically everything on the engine is new, because the engine suddenly started consuming oil, and I couldn’t figure out where it was going. I initially thought the turbos were bad, but that wasn’t the issue. Finally, I measured the compression in the cylinders and found that the pressure in the third cylinder was about 3 bars lower than the others. So, I decided to rebuild the entire engine, including new pistons. Everything was replaced, but the oil consumption problem remained. That’s why I’m looking for any alternative explanation for why it’s pushing oil into the air hoses in such quantities. 1 liter of oil over 50 km doesn’t just end up in the hoses for no reason, but I don’t know how it’s getting there. The oil level sensor is new, and it’s reading correctly, so it’s definitely not overfilled. Thank you for any advice.

Was the oil pump replaced? Just wondering if the pressure relief valve is stuck closed.
If you get the engine properly warm whilst keeping the revs low, does the issue still occur when the revs are increased? Oil pressure at around 1500 rpm before the oil has warmed will exceed the relief valve pressure but will drop to around 35 psi at 3000 rpm once hot. I have a pressure gauge permanently fitted to keep an eye on low pressure.

I assume that you're using the correct viscosity oil.

The oil pump is also new. I think at low RPMs, when I was breaking in the engine, I was driving at a maximum of 2500rpm. But the oil disappeared from the engine into the pipes when I was driving under load at 3500rpm for a longer time uphill. When I arrived, there was oil in the intake hoses.

Any chance that the vacuum/scavanger pump is faulty, pumping oil from the turbo into the inlet tract?