[gT-BMW]

hi i got a n52 with heavy oil consumption at 1 quart every 800 miles. im considering replacing the valve stem seals as it seems this is the source. anybody here done this job and if so any tips?

[lowrydr310]

Originally Posted by gT-BMW

hi i got a n52 with heavy oil consumption at 1 quart every 800 miles. im considering replacing the valve stem seals as it seems this is the source. anybody here done this job and if so any tips?

How do you know it's valve stem seals and not the oil control rings?

[gT-BMW]

Im not sure if i have stuck oil control rings, that could be a possible. Its burning oil in cylinder 6 thats for sure. I took a quick pick of cylinder 6 intake port. Looks like something is happening there. At this point im not sure if i should get this fixed or replace the engine?

[mweisdorfer]

Originally Posted by lowrydr310

How do you know it's valve stem seals and not the oil control rings?

Blue smoke I'm the exhaust = bad valve seals

[gbalthrop]

Originally Posted by gT-BMW

n52 with heavy oil consumption at 1 quart every 800 miles. im considering replacing the valve stem seals as it seems this is the source...[See Alternate Opinion below ]

Originally Posted by lowrydr310

How do you know it's valve stem seals and not the oil control rings?

Originally Posted by gT-BMW

Im not sure if i have stuck oil control rings, that could be a possible. Its burning oil in cylinder 6 thats for sure. I took a quick pick of cylinder 6 intake port. [2 photos attached to Post #3] Looks like something is happening there...

IF your engine had EITHER a bad oil ring or a bad Intake Valve Seal on cylinder #6:
1) WHY would there be oil sludge/carbon ABOVE or UPSTREAM OF the Valve stem and guide in the intake port?
2) HOW likely is it that only ONE Valve Stem Seal, or ONE Oil Ring, would fail, with NO issue in any other cylinder?

3) Have you examined the Intake Manifold, particularly the rearmost intake ports (6,5,4) for signs of oil coming from the Breather Hose from the Oil Separator (I assume your 2006 325i has an External Oil Separator beneath the rear of the Intake Manifold)? ALSO, check the hose from the Oil Separator to the Intake for significant oil.
4) WHEN and under WHAT conditions (startup, WOT Acceleration, Over-run or releasing throttle after High RPM acceleration, etc.) do you see any oil smoke or "puff of smoke" from the exhaust? Get a helper to follow you as you do WOT acceleration in 1st & 2nd and then over-run or throttle release without braking other than engine braking (do NOT depress clutch), to observe exhaust smoke closely.
5) Do you NOW, or have you at any time in the past 6 months, had any fault code related to either bank being too rich, such as P0175, Bank 2 too rich?
6) Have you observed "Fuel Trim" Parameters as Live Data, to determine if one bank is considerably more RICH than the other?
7) Are there ANY performance faults or issues, and if so, at WHAT engine conditions (Temp, Load, RPM) do they occur, WHAT Fault Codes are saved?

Your endoscope photos are helpful. You could perhaps get a better idea of what is really going on if you took some shots of the intake and breather hose.

I've never had or worked on any BMW with the External Oil Separator, but my understanding from posts by owners of such vehicles is that oil ingestion from a faulty Oil Separator normally has MORE oil going into bank 2 than bank 1. That would theoretically make sense to me, due to either inertia or acceleration forces upon the oil film in the manifold, or simply due to oil film adhesion to the surfaces to the rear of the Breather Hose attachment to the Intake.

Even IF you did have an internal problem in the engine such as Oil Ring or Valve Stem Seal or Guide, $5 for a quart of oil every 800 miles will get you a LOT of miles before you spend as much as ANY possible repair alternative.

George