Hello all, bare with me for a bit lengthy explanation. But I seem to have a suspected high-oil pressure issue. I would like to gather everyone's experience before comitting.

My 2008 E60 with N52k (blacktop) seems to have 2 oil leaks at the moment;

• Oil mist around the filler cap (keeps on returning after cleaning)
• Oil leak seamingly from the Oil cooler
  • both cooler and filter housing gaskets replaced about 16,000km ago with genuine BMW, after an evident oil inside the expansion tank, but engine oil when changing did not show any water. There is no oil layers inside the expansion tank now.
  • Oil cooler was pressure tested for leaks but found none, so its reused.

And as for the previous stats:

• Engine runs smoothly in general. But when I bought it, it had (and still has) pretty visible sludge inside the Valve cover. Not caked like a pudding but a thick layer everywhere.
• Oil pan gasket was changed, and did not see any sludge or unusual stuff inside the pan or at the bottom of the block area.
• Cold starts had rough idle, and even when hot, there were sudden RPM spikes after stopping at color lights, etc. And sometimes RPM would go too low when braked to an almost stalling level but quickly comes back to idle level (in stop-n-go traffic, etc.)
• Got check engine light about every 3-4 days, and disappears by itself after about 48hrs with usual daily driving. Scanning each time showed a stored Vanos solanoid code, so I assumed sludge must be passing through the solanoid, momentarily blocking the oil feed.

My effort on the sludge situation;

• Mechanic suggested either short oil changes or a valve cover open and cleanup. I was hesitant on messing with the gunk coz despite this, the engine works flawless, good response, etc. He did one engine flush with liqui molly before adding new 5w30 BMW LL01 oil, but I didnt notice any change inside the VC.
• So I decided to go with the quick oil change.
  • Used one BGR can before flushing the old (about 3,500km run) BMW LL01 engine oil and topped up with Mannol Energy 5W30 with Esther, hoping it will assist in dialuting the gunk.
  • Repeated this process once more = EP BGR >> Mannol Energy 5W30 after about 3,500km.
• My observation on above proceedure:
  • No visible change in the VC (looking through the filler cap)
    • Either all of that just didint work, OR the gunk is being rebuilt as fast as I try to flush it out (is such a thing possible? I dont know)
  • Didnt gain any trust on BG EPR but could be that I have a unique situation as said above.
  • Mannol Energy 5W30: very bad in my case. It ran smooth for 3-4 days and then gradually started to increase engine vibration to such a level that I felt like whether I poured water inside instead of oil. And to make it worst, engine started burning oil on long drives at 140kmph. I guess it thinned to such a level that it seeped past the piston rings. I did a 350km round trip one Sunday, and had to fill about 500-600ml of oil by evening. I didnt have any oil smoke from tailpipes though.
  • RPM surge and Engine light situation gradually increased, but I thought its due to sludge being broken and passing through to the sump. But while the drained oil looked quite thick and brown (not milkey or foaming) visibly, sludge inside VC looks the same.
• Changed the stratergy;
  • decided to still continue with quick oil changes but to stop using flush agents, as I didnt want to damage oil seals.
  • I chose Mannol as a cost effective choice while still holding a promised quality with the benefit of Esther (its only slightly less costly than BMW oil) but it failed on me miserably.
  • This time I decided to use Valvoline Restore & Protect 5w30. Going for a higher expensive option to hopefully actively clean the sludge.

Current situation:

• After removing the last used Mannol oil after 3,500km, filled with above Valvoline RnP 5w30 oil. No flushing agent. Hoping to change again in about 4000km with the same oil.
  • I have run about 1500km now on Valvoline RnP, and observation in terms of engine performance is surprising! So far did not get any Check engine lights, does not seem to burn oil (did another singe-day long run, no loss of oil) engine continues to feel super smooth (as same as or might be even better than BMW oil). RPM fluctuation is occured rarely now, and did not have any sudden spikes, nor RPM stall-drops at all so far.
  • Too soon to tell anything on the sludge removal, Valvoline RnP says it needs about 4 oil changes to show effects on gunk, soot and sludge.

Back to my problem:

• Parallelly I am trying to find the cause of the sludge on this otherwise healthy engine, and suspicious on the fact that whether it keeps rebuilding as fast as I work on dialuting it. This suspicision is pointed towards a failed CCV. Plastic valve cover has the CCV valve built into it, but since my VC itself and its gasket seems good, I intend to do a DIY diapraghm change with a repair kit. I dont feel much of a vaccum pressure from the Oil filler cap opened when running. But noticing the oil mist on the filler cap collar and from the newly changed OCG/OFHG, (I cleaned both points and within days the mist returned) I suspect that maybe it has a excessive oil pressure problem rather than more common negative oil pressure.

Does my oil mist situation happen due to excessive engine oil pressure? If so, would that happen due to a failed CCV? And would sludge build up due to a failed CCV (more common) or CCV can fail due to the sludge clogging?

Im looking for some opinions backed with experience before ordering a CCV rebuild kit and butchering the plastic Valve cover. Coz I dont want the new CCV also to fail due to sludge (if its caused by some other reason).

 

Sounds very much like a failed PCV, which as you know is integrated into the valve cover. Given the valve cover is so fouled with sludge, I think a rebuild kit for the PCV is out as there are passages inside the valve cover and those are likely fouled as well. Just get a new valve cover.

I'd change the valve cover and drive it for some days before digging further into the oil filter housing and oil cooler.

 

I concur. Change VC and observe

 

To follow up on this matter. I took to a DIY inspection + decided that ill change the "integrated" PCV first and try, since my VC and gasket seems in good condition.

• There was oil around one of the coil (only on the VC, not inside the coil well) and oil mist covering half of the VC. To the fear of my eyes, there was oil all around the Eccentric sensor also.
  • When I chased the oil mist, it was originating from the filler cap. Either the cap gasket was leaking, or the lousy refill has leaked oil, a.k.a messed up simplest job.
  • I cleaned the whole thing everywhere, including the filler cap.
  • Eccentric shalf was bone dry inside the pins area. So I cleaned the surrounding well and plugged it back.
• I am going to run as is for some time and remove the beauty cover again to inspect, before another oil change. If there is oil mist again, then its not a lousy change job.
• I broke-removed the previous PCV valve.
  • There is no way to remove it, you have to demolish it without damaging the VC. Not hard at all, but time consuming. And I had to be carefull not to damage the VC mouth, and not to let the debris go inside the Valvehead.
  • Upon careful inspection, I noted that the PCV (99% sure its the factory fitted VC and PCV) was not yet cracked, hence I must not have had a PCV pressure issue. However, it was so brittle that it easily crumbled in my hand with feather-effort. So chalked it up as a preventative maintenance.
  • New one was a snug satisfying fit, with some RTV silicone for added sealing. Let it dry overnight for 12hrs+.
  • Now when I remove the oil filler cap while Engine is running, there is a small vaccume, but not huge to suck the cap back, and engine doesnt try to stall or as such (I assume that is how it should be properly functioning.....)

Monitoring the oil cooler issue. Showed it to my mechanic again as they worked on it. He said that there is a chance that the leak is due to oil spill when changing the filter. We decided to clean the oil mist and then observe for some time.

 

Hello. You are over-reacting without undertaking the proper diagnosis to rule out potential malfunctions.

Just like the previous answers, I highly recommend changing the valve cover (get it from the dealership) + the vacuum hose at the back + the valvetronic actuator motor gasket.

The new pcv will not fail because of overpressure as you reported that the engine runs smooth and idles correctly.
First of all:
- Measure your crankcase vacuum when the engine is hot and idling: https://n52.opentika.ovh/n52_data (ideal.value is -33mbar). This will rule out any overpressure issues.

- Secondly, measure compression, engine hot and eccentric shaft angle is 176° : https://n52.opentika.ovh/compression

Pressure issues can be caused by blowby in one or multiple cylinders. It will cause the oil.to leak past the oil filler cap, valve cover, front/rear main seals and ES motor gasket.

- Thirdly, you need to make sure the cylinder head filters are not clogged, I bet they are. Don t clean them, get new OE ones from the dealership (remove the wheel arch liner for easy access). They also cause pressure issues and vanos intermittent codes.

- By that mileage the vanos solenoids are already worn (even if they are not jammed or throw a code). Get them from the dealership.

- Make sure the oil filter housing is complete and that filter is a BMW OE or MANN. I ve seen pressure issues because of this.

For sludge, let Valvoline RP do its job for at least 15K miles and monitor the filter every 600 miles.
Once the cleaning process is finished you can return to what I think is one of the best oils for the N52: Mobil 1 ESP 0W30.

You can check read about the N52 oil.consumption on here: https://n52.opentika.ovh/oil_consumption

If you have a good scanner, let us know about your fuel mixture data and vanos data, especially adaptations.